t H. D. GARDEIL, O. P-

Introduction to
the Philosophy of

St. Thomas Aquinas
IV. METAPHYSICS

Translated hy John A. Otto,

B. HERDER BOOK CO.
374 North Jefferson, St. Louis, Missouri
and

2/3 Doughty Mews, London, W. C. 1

ph.d.

This book originally appeared under the title Initiation à la
philosophie de S. Thomas d’Aquin: Vol. IV, Métaphysique,
and was published by Les Éditions du Cerf, of Paris, France.

IMPRIMATUR
►J* Joseph Cardinal Ritter

Archbishop of St. Louis
March i, 1967

Library of Congress Catalog Card Number: 56-9194

COPYRIGHT © 1967 BY B. HERDER BOOK CO.

Printed in the United States of America
by 'Vail-Ballou Press, Inc., Binghamton, New York

t

Foreword

f AS part of the series we have entitled Introduc­
tion to the Philosophy of St. Thomas Aquinas this volume,
like the others, claims but modest scope and purpose; for,
it bears repeating, the series as a whole is meant to be just
what the title says, an introduction, a helping hand to those
who are beginning the study of St. Thomas and desire to
read him in his own words. Accordingly, though the im­
portant problems have all, in varying degree, been exam­
ined, the present volume does not pretend to be a com­
plete elaboration of Thomistic metaphysics. Even in a
modest work of this nature some choice, however, has to
be made in organizing the material and interpreting the
doctrine. What has in this regard seemed best to us will
appear as the work progresses; it need not, then, be gone
into here.
To this final volume of the series—final, at least, as of
now—is appended a glossary of St. Thomas’ technical
V

vi

Foreword

vocabulary, held of necessity to terms most frequently met,
which are defined according to their most usual sense.
While some of the terms, as terms, have their popular
usage, in St. Thomas, it should be noted, as for that matter
in Scholastic literature generally, they have a meaning of
their own, formal and precise, without the grasp of which
no real understanding of Thomistic thought is possible.
The glossary, such as it is, covers all four volumes of the
series: Logic, Cosmology, Psychology, and Metaphysics.
To the presentation of this volume many have in one
way or another made valuable contribution. It is with great
pleasure that we acknowledge our indebtedness to them,
particularly to the confreres Father Guérard des Lauriers
and Father Hubert.

t

Acknowledgments

t THE volume here offered in translation is the
fourth in a four-volume series by H. D. Gardeil, O.P.,
titled Initiation à la Philosophie de S. Thomas d’Aquin
(Paris: Les Éditions du Cerf, 1952-1953; 3e édition, i960).
Previously translated and published have been Vol. II,
Cosmologie,1 and Vol. Ill, Psychologie.2 In process of
translation is Vol. I, Logique.
The English translation of quotations and selections
from St. Thomas is taken from various sources. Acknowl­
edgment is due the following publishers for permission
to quote, one or more passages (as the case may be), from
the works indicated:
1 Introduction to the Philosophy of St. Thomas Aquinas: II,
Cosmology; trans, by John A. Otto (St. Louis & London: B. Herder
Book Co., 1958).
2 Introduction to the Philosophy of St. Thomas Aquinas: III,
Psychology; trans, by John A. Otto (St. Louis & London: B. Herder
Book Co., 1956).
vii

viii

Acknowledgments

Doubleday & Company, Inc.: On the Truth of the Cath­
olic Faith, by Anton Pegis. (Copyright 1955 by Doubleday
& Company.)
Henry Regnery Company: Commentary on the Meta­
physics of Aristotle, translated by John P. Rowan. (Copy­
right Henry Regnery Company, 1961.)
---------------- : Truth, Vol. Ill, translated by Robert
W. Schmidt, S.J. (Copyright Henry Regnery Company,
1954-)
The Newman Press: On the Power of God, translated
by Laurence Shapcote, O.P. (First published 1932; re­
printed by The Newman Press, 1952. All rights reserved.)
The Pontifical Institute of Mediaeval Studies: On Be­
ing and Essence, translated by Armand A. Maurer, C.S.B.
(Copyright by The Pontifical Institute of Mediaeval
Studies, 1949.)
Random House, Inc.: Basic 'Writings of St. Thomas
Aquinas, edited by Anton C. Pegis. (Copyright, 1945, by
Random House, Inc.)
For English quotations from Aristotle, I found Ross’
The Student’s Oxford Aristotle (Oxford University Press,
1942) a useful reference, but final responsibility for each
instance rests with myself. Lastly, paragraph numbers for
the Commentary on the Metaphysics are according to the
Cathala-Spiazzi edition (Rome & Turin: Marietti, 1950).

J. A. O.

t

Contents

.................................................. v

Foreword

Acknowledgments......................................................vii
CHAPTER

i. Introduction................................................................... i

I.General Notion

of

Metaphysics

i

II. Metaphysics As Wisdom.................................. 5
III. Metaphysics As

the Science of What Is
Separate from Matter................................ 16

IV. Metaphysics As the Science of Being
As Being...........................................

.

21

V. Metaphysics

and Critique of
Knowledge...........................

25

.VI. The Metaphysical Work
and

of Aristotle
St. Thomas: Problems and

Procedure...................................................... 29
ix

x
2. Being: Metaphysical

Contents
Study....................................35

I. The Starting Point of Metaphysics .
-35
II. The Metaphysical Notion of Being ... 38

III. Concerning
of

the Structure of the Notion
Being............................................... 44

IV. The Doctrine

V.

The Analogy

........................... 47

of

Analogy

of

Being....................................64

3. Being: Criteriological Study.....................................73

I. Critique

of

Realism..................................... 75

II. Starting Point of a Thomist
Epistemology................................................ 82

III. Concerning
of

the Authentic Foundation
Realism..................................................... 96

.........................106

IV. First Principles

4. The Transcendentals.............................................. 119

I. The Transcendentals in General .
II. The Transcendentals

in

.

. 128

Particular .

III. Conclusion: the Transcendentals As
System......................................

.119

a

149

5. The Predicaments.................................................... 153

I. Substance......................................................... 154
II. Accidents............................................

.169

6. Act and Potency......................................................... 183
1. Genesis of the Doctrine of Act and
Potency...........................................
.183
2. Potency...............................................................187

Contents
xi
3. Act.......................................................
191
4. Concerning the Relation of Act and
Potency.......................................................... 193
5. Conclusion: Act and Potency As the
Cardinal Principles of Thomistic
Metaphysics.................................................... 198

7. Essence and Existence.............................................. 201
1. The Problem of the Real Distinction . . .201
2. Historical Sketch of the Problem ... 203
3. Proofs of the Real Distinction .... 205
4. True Sense of the Distinction.........................207
5. Composition of Created Substances,
Simplicity of Uncreated Being .... 209
6. Originality of St. Thomas’ Doctrine of
Being............................................................... 211
8. Causality . ................................................................... 215

I. Causality

in

Aristotle and St.Thomas .

II. Critical Justification

ofCausality

.

.

215
. 223

III. The First Cause . ............................................. 229
Texts

235

I. The Prerogatives of Metaphysics
(In I Metaph. Leet. 3, nos. 53-65) • • • 238
A. Metaphysics is a speculative science 239
B. Metaphysics is a free science . . . 241
C. Metaphysics is not a human science
[possession]................................... 242
D. Metaphysics is the most honorable
of all sciences ...... 243

xii
Contents
II. The “Subject” of Metaphysics
(In IV Metaph. lect. 4, nos. 529-547) . . 244
A. The “subject” of metaphysics is being
as being......................................... 244
B. Metaphysics considers both
substance and the accidents . . . 245
C. Metaphyics treats principally
of substance................................... 248
HI. The Study

of the

One Pertains to

Metaphysics

(In IV Metaph. lect. 2, nos. 550-553,
559-560) ...........................................
A. One and being are really identical
but differ conceptually .
B. The transcendental one and one,
principle of number ....
IV. Concerning

the First Principle
Demonstration

249
■ 249

. 250

of

(In IV Metaph. lect. 6, nos. 597-608) . . 252
A. Conditions which the most certain
principle must meet.......................252
B. Which principle meets these
conditions?................................... 253
C. Errors committed in regard to this
principle.........................................255
V. Principal Modes of Being
(In V Metaph. lect. 9, nos. 885-886,
889-892, 895-897) ............................. 256
A. Essential being and accidental being
(ens per se, ens per accidens) . .258

Contents

xiii
B. The modes of essential being (ens
per se).............................. 258

VI. Metaphysics As the Science of Substance
(In VII Metaph. lect. 1, nos. 1248-1255,
1257-1259).............................. 260
A. Substance is first being........................ 261
B. In what respects substance is first
being.............................................. 262

VII. Potency and Act........................................... .263
A. Explication of potency
(In IX Metaph. lect. 1, nos.
1773-1780).............................. 264
B. Explication of act
(In IX Metaph. lect. 5, nos.
1825-1831)
........................... 267

VIII. God Is Life
(In XII Metaph. lect. 8, no. 2544) .

IX. One

as

Principle of Number

and

.

. 269

One As

TRANSCENDENTAL

(De Potentia, q. 9, a. 7).............................. 270

X. Logical Truth and Ontological Truth
(Summa theol. la, q. 16, a. 1 corp.) .

. 272

XI. Whether Good Adds Anything to Being
(De Verit. q. 21, a. 1)...................... 274

XII. Concerning Being and Essence
A. On the meaning of the words “being”
and “essence”
(De Ente et Essentia, Introduction
& chap. 1)................................... 277

xiv

Contents
B. Essence in composite substances
(De Ente et Essentia, chap. 2) .
278
C. Essence in separate substances
(De Ente et Essentia, chap. 4) . . 279
D. Conclusion: Three ways essence is
found in substances
(De Ente et Essentia,
chap. 5)................................... 284

XIII. That

in

God Essence

and

Existence Are the

Same

(Summa Contra Gentiles, I, 22) .

XIV. Is It Necessary
Created

by

that

■ 287

Every Being Be

God?

(Summa theol. la, q. 44, a. 1)

■ 291

Glossary of Technical Terms................................... 295
Index......................................................................... 323

Introduction to the Philosophy
of St. Thomas Aquinas

IV.

METAPHYSICS

t CHAPTER 1

Introduction

I. GENERAL NOTION OF METAPHYSICS
t IN philosophic idiom the word metaphysics de­
notes the higher branch of philosophy, the part that seeks
after the most basic principles of things, their ultimate
ground and nature. The word itself was first suggested by
Andronicus of Rhodes (2nd century B.C.), the first redactor
of Aristotle’s complete works. Under the heading of Meta
ta Phusïka (lit. “after the Physcals”) Andronicus placed a
group of fourteen books (long “chapters,” in modern de­
scription) whose content seemed to follow logically after
the books of the Physics. Yet Aristotle himself had never
spoken of these fourteen books or of their content as “meta­
physics” but always as “first philosophy” or as “theology.”
The proper object of metaphysics, or its special reference
of inquiry, in Aristotelian thought is, we shall see, being as
being together with its properties. But the proper object,
or at least this determination of it, is not clear-cut from the
outset; indeed, a first survey of the Metaphysics reveals
what amounts to three successive conceptions of the science,

2
Philosophy of St. Thomas: Metaphysics
yet on the face of it there is no firm indication how they
are to be integrated. St. Thomas, who accepts the Aristote­
lian view of the proper object, was aware that the threefold
conception lay, or so it seemed, unresolved and went to
some pains to clarify it; which he does in the Prologue to
his Commentary. Among the points made are these:
First, in contrast to other sciences, which explore only the
more immediate principles and causes, metaphysics stands forth
as the science of first causes and first principles. This definition
echoes the general notion of science, for in the Aristotelian tra­
dition it is axiomatic that science, all true science, consists in
knowledge through causes: cognitio per causas. It is from this
point of view that metaphysics is properly called “first philoso­
phy,” the conception that predominates in Book A of Aristotle’s
treatise.
Secondly, metaphysics can also be envisioned as the science
of being as being and of the attributes (or properties') of being
as being, a view of the science which points to the comprehen­
siveness of its object. Unlike other sciences, each of which con­
siders only a particular province of being, metaphysics, the
science of being as being, embraces all being. This conception is
developed in Book r and appears to be upheld in the sequel. It
is the conception which corresponds to the word “metaphysics”
in its proper sense.
Thirdly, metaphysics can be defined as the science of the im­
mobile (i.e. the motionless or unchanging) and the separate (i.e.
from matter). In this it differs from the philosophy of nature or
physics in the Aristotelian sense and from mathematics; for the
proper object of these sciences always retains some mode of
materiality. Moreover, among beings that are separate (i.e. free)
from matter must be reckoned God, who is indeed furthest
removed. Consequently, metaphysics understood as the science

Introduction
3
of the separate includes the study of God and is not improperly
spoken of as “theology,” the conception that preponderates in
Book E and thereafter.

St. Thomas’ Prologue is, however, too important to be
dismissed with passing summary; it should be read clear
through with close attention. Note especially his analysis
of the primacy that metaphysics enjoys among the sciences.
Metaphysics, he observes, governs and directs all other
sciences, and this in virtue of the principle that the most
intellectual science is the ruling science. But then, why
should metaphysics be the most intellectual science? The
answer is because its object are the “most intelligibles,”
beings and modes of being of the highest intelligibility.
This notion “most intelligible” admits, however, of a three­
fold sense; and thereby hangs the threefold conception.
For the explanation, here is St. Thomas himself:
First, [“most intelligible” can be understood] from the view­
point of the order of knowing; for those things from which the
intellect derives certitude seem to be more intelligible. There­
fore, since the certitude of science is acquired by the intellect
knowing causes, a knowledge of causes seems to be intellectual
in the highest degree. Hence that science which considers first
causes also seems to be the ruler of the others in the highest
degree.
Second, this phrase can be understood by comparing the
intellect with the senses; for while sensory perception is a
knowledge of particulars, the intellect seems to differ from sense
by reason of the fact that it comprehends universals. Hence that
science is pre-eminently intellectual which deals with the most
universal principles. These principles are being and those things
which naturally accompany being, such as unity and plurality,

4
Philosophy of St. Thomas: Metaphysics
potency and act. Now such principles should not remain en­
tirely undetermined, since without them a complete knowledge
of the principles which are proper to any genus or species can­
not be had. Nor again should they be dealt with in any one
particular science, for, since a knowledge of each class of beings
stands in need of these principles, they would with equal reason
be investigated in every particular science. It follows, then, that
such principles be treated by one common science, which, since
it is intellectual in the highest degree, will govern the others.
Third, this phrase can be understood from the viewpoint of
the intellect’s own knowledge. For since each thing has intellec­
tive power by virtue of being free from matter, those things
must be intelligible in the highest degree which are altogether
separate from matter. . . . Now those things are separate from
matter in the highest degree which abstract not only from
signate matter . . . but from sensible matter altogether; and
these are separate from matter not only in their intelligible con­
stitution [ratio], as the objects of mathematics, but also in being,
as God and the intelligences [spirits]. Therefore the science
which considers such things seems to be the most intellectual
and the ruler and master of the others.1

These, then, are the various aspects to metaphysics: sci­
ence of first principles and first causes (which is to say,
wisdom), science of being as being, and science of what is
utterly separate from matter. Our next step will be to ex­
amine these formulations in some detail, and thus provide
a better understanding of the underlying notion in each
case. To this end we shall, among other things, trace their
development in Greek thought and observe how they align
1 Commentary on the Metaphysics of Aristotle, Prologue. English
citations from this Commentary will be, throughout the present
volume, in the translation of John P. Rowan, published in two vol­
umes by Henry Regnery Company: Chicago, 1961. (Copyright
Henry Regnery Company, 1961)

Introduction
5
themselves with the course of that thought as a whole. So
doing, we shall be reminded that Aristotle is not without
ancestry, that though his metaphysical accomplishment is
a triumph of discovery and elaboration in its own right, it
may also be seen as the culminating synthesis of a meta­
physical enterprise stretching back three centuries before
him.
II. METAPHYSICS AS WISDOM
1. General Notion of Wisdom

In the first book of the Metaphysics 2 Aristotle recounts
the most commonly accepted notions regarding the quali­
ties of philosophical wisdom. Thus, wisdom is thought to
be the most universal (i.e. the most inclusive) science, and
the most difficult, and the most deserving of being taught.
Aristotle does not cast these notions aside, but to him the
truest characteristic of wisdom is this: it is science of first
causes and first principles. Pursuing this thought, he ob­
serves that man has an inborn curiosity about things, a
natural desire to know their causes, and this desire is not
satisfied until the ultimate cause is reached, beyond which
no other is to be found and which must therefore be selfsufficing. Whatever science delivers the ultimate explana­
tions, which is to say the ultimate or first causes, that science
is wisdom. And since metaphysics does this, it is rightfully
called wisdom.
2. The Several Kinds of Wisdom
a) The notion of wisdom is as little the exclusive property
of Aristotelianism as it is of Christianity. Every philosoph­
ical system worthy of the name purports to be wisdom. Yet
2 Metaph. A, 2.

6
Philosophy of St. Thomas: Metaphysics
there are wide differences within philosophical wisdom
itself, depending on the goal pursued and the means and
method employed.3
In earliest Greek usage the word “wisdom” (sophia) had
a decidedly utilitarian connotation, being synonymous with
skill or excellence in any craft. So, Polycleitus was wise be­
cause of his exceptional competence as sculptor. But
“sophia” also meant a certain mastery in the conduct of
one’s life. In this superior sense Socrates speaks of it. Wise,
he said, is he who knowing himself well, knows how to
govern himself truly. Plato, making the moral heritage of
Socrates his own, carried it a step further, acclaiming wis­
dom the art of governing, by the norms of justice and
prudence, not merely oneself but the whole city or state.
Philosopher of the Ideas, Plato went on to discover new
paths to wisdom for the human soul. By its intellectual
element called Nous, this soul was said to be in com­
munication with the true realities, those same intelligible
forms or Ideas pinnacled by the Good, highest of them all.
Wisdom, by this stroke, assimilates to theoria or contempla­
tion—contemplation of the Ideas and, in the final phase,
of God. Aristotle and Plotinus, the most eminent disciples
of Plato, followed their master in seizing upon and espous­
ing this intellectual ascent toward the highest being. All
told, then, among its most dedicated followers and within
3 Indeed, as the author suggests, not only does one philosophical
system differ from another, but within the same system one branch
may differ greatly from another in intention, in manner of demon­
stration, in degree of certitude attainable, etc. It is on these and
similar counts that speculative philosophy, to take a broad example,
differs from practical philosophy and that each of these divisions
admits of differences within itself.—Translator’s note.

Introduction
7
the limits placed on sole human access, philosophic wisdom
did espy its true source and principle. But one essential
continued to elude it; for though this wisdom had dis­
cerned, however dimly, the path to God, it was and re­
mained ignorant of the means to secure him effectively.
In the Judeo-Christian revelation, contemplation of God
is likewise the ultimate goal of wisdom, but there is a com­
plete turnabout of perspective. No longer is wisdom to be
attained from below as by mere human effort. It issues from
above, from heaven. In short, it is salvation, bestowed by
God at his pleasure and through his grace. Wisdom in this
light is from its very inception something that exceeds
philosophy, though even under the sovereignty of grace it
is perfectly possible for an authentic philosophic wisdom
to be constituted.
Squarely opposed, however, to the wisdom that is God’s
dispensation is that attitude which the gospel labels the
wisdom “of this world,” warning us against it. Basically,
this consists in the refusal of the transcendent, of anything
that is not authored by man himself. It betrays itself in the
studied determination to administer all the affairs of the
world along secularistic lines, with no thought to supramundane man and his wants. To the Christian this is, of
course, no more than the pretense of wisdom, false and de­
ceitful, like the ideals its professes.
b) In the foregoing paragraphs we spoke of wisdom from
an historical aspect. Considering it doctrinally, or as to con­
tent, we find that St. Thomas together with Catholic
theologians in general, acknowledges three possible forms
of wisdom for the human soul, wisdoms which, though
essentially different, are not opposed to each other but

8
Philosophy of St. Thomas: Metaphysics
related in hierarchical fashion. They are: infused wisdom
(gift of the Holy Ghost), theology, and metaphysics, which
differ each from the other on two counts; for each has its
special light of understanding and each its own formal
object.
By infused wisdom the soul judges in the light of con­
natural knowledge, connatural by grace with God’s
knowledge; its foundation is the love that is charity (in the
gospel sense), and its object is God as he is in himself but
attained through a suprahuman mode of acting, or rather
of being acted on. Theological wisdom is, like the preced­
ing, under the rule of supernatural faith, and its object is
also God as he is in himself; but its immediate foundation
is revelation and not charity, and its mode of activity is
essentially the human mode of reason. Metaphysics, on the
other hand, is a purely human wisdom; its only light is
natural reason, and though it also seeks to know God the
supreme principle of things, it knows him only as inferred
cause (hence indirectly), and not as he is in himself (as an
object directly apprehended).
Christian thought knows of yet another meaning for
wisdom when it uses the term to designate that essential
attribute of God which is his substantial Wisdom and
which the theology of the Blessed Trinity refers to the
Person of the Son. This Wisdom, it should be noted, is
the common origin of the three wisdoms spoken of above,
which enlighten the human soul in ascending manner and
measure; it is also, and for that very reason, the principle by
which, in the last analysis, each finds itself in perfect ac­
cord with the other. Far from being opposed, therefore, the
three wisdoms accessible to the Christian complement each

Introduction
g
other in perfect harmony, and for a man to be most truly
wise is to grow unceasingly in all three of them; for each
is a participation, one more perfect than the other, in that
highest wisdom which is God’s own measure and mani­
festation of the universe.
3. Wisdom, Science, and Understanding

Having spoken, though but broadly, of wisdom as to its
object or content, we have now to consider it from the
standpoint of the subject, the person possessing it. Also
brought up for review, by way of comparison, will be the
allied notions of science and understanding.
Taken in its subject, wisdom according to St. 'Thomas is
a habitus or virtue of the intellect. Since any virtue is a per­
fection, this one is a perfection of intellect. And in what
does this perfection consist? In making it possible for the
intellect to perform its activity, or at least some part of its
activity, with ease and exactitude.
Here a few words on the basic classification of virtues will
be in order. According to Aristotelian doctrine human
virtues are of two general kinds: moral virtues, which reside
in and perfect the appetitive powers; and intellectual vir­
tues, which reside in and perfect the intellect. Our present
concern is with the intellectual virtues. Of these according
to Aristotle,4 and St. Thomas agrees,5 there are five distinct
species. Three of them—science, understanding, and wis­
dom—pertain to the speculative intellect; the other twoprudence and art—to the practical intellect. If, then, along
with wisdom there are two other virtues (habitus') of the
4Cf. Ethica Nic. Book VI.
5 Cf. Summa theol. la Ilae, q. 57, aa. 2—4.

io
Philosophy of St. Thomas: Metaphysics
speculative intellect, namely science and understanding, in
what do they differ?
The answer lies in the following considerations. The
proper perfection of the speculative intellect is the true,
which may, however, he attained in two ways: either as
known in itself, immediately (per se notum), or as known
in another, mediately (per aliud notum).
Keeping this distinction in mind, we go a step further.
What is known in itself is by way of a principle (as against
a conclusion) and, to repeat, is grasped immediately by the
intellect. To this end the intellect is perfected by the virtue
called intellectus or understanding.6 On the other hand,
what is known in another is in the nature of a terminus (as
against a principle or starting-point). Here again we find
two possibilities. Either the truth that is known stands as
term or conclusion of a particular branch of knowledge, in
which case the intellect is perfected by the virtue called
science; or the truth in question represents the ultimate
term of all human knowledge, in which case the intellect is
perfected by the virtue called wisdom.
Wisdom, accordingly, is a habitus (virtue or quality)
which perfects the speculative intellect. But this does not
yet distinguish it from the other speculative intellectual
virtues, science and understanding. What is unique to wis­
dom is that it perfects the intellect in its quest of knowl­
edge that is absolutely universal, the quest to proceed from
principles and reasons which in their own order are ultimate
or highest—“in their own order,” because theological wis­
dom, for example, uses different principles and reasons from
6 This use of “understanding” should not be confused with the
more popular sense of “discernment” or “comprehension.”—[Tr.]

Introduction
11
metaphysical wisdom. One important conclusion to be
drawn from all this is the following. If science, as an intel­
lectual virtue, pertains to a particular branch of knowledge
and there are many such branches, or at least more than
one, obviously there can be more than one intellectual
virtue of science; but of wisdom, which judges of things
universally, there can be but one virtue under the same
formal light, be this reason, revelation, or divine infusion.
Further questions, however, suggest themselves, to which
we shall next give attention.
a) Is it correct to draw an irreducible distinction, as we
have done, between wisdom on the one hand and science
and understanding, on the other? There are really two, if
not three, questions involved here. For one, wisdom is said
to explain things through their causes; but so does science,
which in general is defined as knowledge through causes.
Is wisdom, then, a science? The answer is yes, if we take
science in the more general sense of knowledge through
causes; no, if we apply the term strictly, which limits science
to one of the intellectual virtues explained above.7
Secondly, for the knowledge of first principles St.
Thomas, as we have seen, posits a separate virtue called
intellectus, generally rendered “understanding.” Is such a
separate virtue necessary or justified, considering that the
principles in question must also be known by science and
wisdom, since all their reasoning is based on them. Never­
theless, the distinction between understanding on one side
and science and wisdom on the other is not thereby erased;
for they do not know the principles in exactly the same
7 Cf. Summa theol. la Ilae, q. 57, a. 2, ad 1.

12
Philosophy of St. Thomas: Metaphysics
way. The virtue of understanding is reserved for the pure
apprehension of the principles, no account taken of their
application; whereas by science and wisdom the principles
are apprehended in their relation to the truths which flow
from and depend on them.8
But this answer casts up another doubt. If, in other
words, the virtue of wisdom holds its basic principles from
understanding, which grasps them in themselves, it would
seem that wisdom is not, after all, the highest of the in­
tellectual virtues. St. Thomas, in reply, notes that wisdom
is in a privileged position as regards first principles; it not
only knows and uses them, as does every science, but to it
falls the higher function of evaluating and defending them
against their critics. As knowledge of conclusions (rather
than principles) wisdom resembles the intellectual virtue of
science, yet is higher than science because its conclusions
are of a higher order; whereas in declaring and defending,
and not simply knowing, the first principles wisdom excels
the mere habit of the principles, or understanding. Wisdom,
in fine, is the highest intellectual virtue.9
b) Is wisdom purely speculative, or is it also practical?
Generally speaking, the present tendency is to attribute
both qualities to wisdom, namely, to regard it as at once
speculative (knowledge for its own sake) and practical
(knowledge regulating conduct). St. Thomas, for whom the
matter is not quite so simple, answers as follows.
Wisdom that is directly under the rule of faith is both
speculative and practical; it establishes both the order of
knowledge and the order of human activity. Such is the
8 Cf. ibid, ad 2.
8 Cf. Summa theol. la Ilae, q. 66, a. 5, ad 4.

Introduction

x3

wisdom that is the gift of the Holy Ghost.10 Such, too, is
supernatural theology, for though primarily speculative, it is
also a practical science.11 Metaphysics, on the other hand, is
by Aristotelian tradition placed among the purely specu­
lative virtues. Indeed, Aristotle himself seldom if ever
passes an opportunity to underscore its utterly disinterested
character, always grouping it with physics and mathematics
to form the triad of theoretical (i.e. speculative) sciences,
which differ by their end from the practical sciences.12
Supreme theoretical wisdom of the natural order, meta­
physics in short is a purely speculative, meaning contem­
plative, science—not, you remember, the virtue “science,”
but in the more general sense of knowledge through causes.
c) The proper acts of wisdom. St. Thomas regularly
refers two types of intellectual acts to wisdom, viz. to
judge and to order. As he remarks on numerous occasions,

ad sapientem pertinet judicare et ordinare,
“to the wise man does it belong to judge and to order.”
How are we to understand this judging and this ordering?
The “judgment” in question, to speak of this first, is not
just any kind but one that is enunciated by the intellect on
the highest evidence, ultimately on the evidence of the
supreme principles; it is a judgment of apical validity, a
definitive determination of right order so final and authori­
tative that there is no going beyond it.
Similarly, while to order is in general to bring things in
line with an end of one kind or another, in respect of
10 Cf. Summa theol. Ila Ilae, q. 45, a. 3.
11 Cf. Summa theol. la, q. 1, a. 4.
12 Cf. Metaph. E, 1.

14
Philosophy of St. Thomas: Metaphysics
wisdom this end can only mean the highest one of all.
Consequently, for a wise man to order consists in referring
all things back to God. In its full application, moreover, to
order is not only to discover or to contemplate an existing
order but also to create an order by will and other powers
of action. Nevertheless, the mere intellectual consideration
of an existing order may also, in a modified sense, be re­
garded as an “ordering,” since this consideration, too,
involves the act of putting things in order, albeit the order
is made in and for the intellect alone. It is in this limited
sense that we should understand the ordering activity of
metaphysics, which, as we have seen, is a purely speculative
science. But practical or speculative, true wisdom will re­
flect that ultimate judgment and ordering that is God’s.
4. The Excellence of Wisdom

For St. Thomas the excellence of a virtue is measured
principally by the perfection of its object, of what comes
within its proper purview. By this standard wisdom is
clearly the most excellent of virtues, since it inquires of the
highest of causes, which is God, and judges of all things
in the light of this cause. In addition, because of its
superior point of view—superior in virtue of its superior
object—wisdom presides over the other intellectual virtues;
these, accordingly, are subordinate to wisdom, falling as
they do under its judgment and its power to order all
things.13 St. Thomas, it may be mentioned, notes some
doubt as to this subordination. Man, runs the objection,
can have more perfect knowledge of things human than of
things divine, wisdom being concerned with the latter. But
13 Cf. Summa theol. la Ilae, q. 66, a. 5.

Introduction
i5
the objection does not hold, at least for St. Thomas, who
replies that it is worthier to acquire what little knowledge
is possible of higher things than a whole lot of knowledge of
lesser realities.14
Aristotle is of similar mind. Though in some respects
he left the matter hovering, he was not unaware that first
philosophy (metaphysics, hence wisdom) owes its excellence
to the pre-eminence of its principles. He calls it, in fact, a
divine science, having a divine object; but instead of its
prerogative to judge and to order, he is more inclined to
extol its privilege of being free and autonomous, existing,
that is, for its own sake. “For just as we call that man free,”
he remarks, “who exists for his own sake and not for the
sake of another, so this science, too, is the only one of all
the sciences that is free, since it alone exists for its own
sake. Hence also there is some ground for regarding its
possession beyond human power.” 18 In the highest sense
of the word the wise man is thus a free man, with all the
superiority this freedom confers.
But if wisdom makes a man free, it promises still more.
What these further rewards are may be seen from this
passage of St. Thomas, in which he praises the quest of
wisdom:
Of all human pursuits, that of wisdom is the most perfect,
the most sublime, the most profitable, the most delightful. It is
the most perfect, since in proportion as a man devotes himself to
the pursuit of wisdom, so much does he already share in true
happiness, ... It is the most sublime because thereby especially
does man approach to a likeness to God, who made all things in

14 Cf. ibid, ad 3.
15 Metaph. A, 2, 982 b 25-30.

16
Philosophy of St. Thomas: Metaphysics
wisdom (Ps. 103:24), ... It is the most profitable, because by
wisdom itself man is brought to the kingdom of immortality,
... It is the most delightful because her conversation hath no
bitterness, nor her company any tediousness, but joy and glad­
ness (Wis. 8:i6).16

Doubtless, this encomium of the Angelic Doctor’s, in
which breathes his own enraptured soul, is not borne out
in full except by wisdom founded on divine revelation; but
measure for measure it finds fulfillment in metaphysical
wisdom, too, the highest knowledge this side of revelation.17
III. METAPHYSICS AS THE SCIENCE OF
WHAT IS SEPARATE FROM MATTER

1. Origins of the Doctrine of Separation

Metaphysics, we have said, may also be understood as
the science of what is utterly separate, or devoid of matter.
Like many another doctrine in Greek thought, this one of
separation, or distinguishing mind and matter, evolved
gradually through a long line of philosophical thinkers. Its
classical formulation in Aristotle represents, therefore, the
efflorescence of an idea whose roots ran at least as far back
as Anaxagoras, the first, or so it is commonly accepted, to
put forth a separation, that is, distinction of mind from
matter. It should be noted, however, that the Nous he
proposes for meditation is not yet clearly differentiated
10 Contra Gentiles, I, 2.
17 Cf. Text I, “The Prerogatives of Metaphysics,” p. 238. On the
general theme of wisdom, in particular its developments in modem
philosophy, the reader could profitably consult Dr. James D. Collins’
1962 Marquette University Aquinas Lecture, namely The Lure of
Wisdom (Milwaukee: The Marquette University Press, 1962); also,
in the same series, Professor Gilson’s 1951 Lecture, Wisdom and
Love in St. Thomas Aquinas.—[Tr.]

Introduction
17
from corporeal objects, nor is its influence on these objects
sharply defined. Still, a first step was taken by him toward
the separation from matter of an element of being that lay
beyond matter.
With Plato the separation is decisive. The world of
Ideas he postulated is a world of realities without so much
as the shadow of matter attaching to them. For him, the
Ideas were the necessary answer to the problem of intel­
lectual knowledge. They alone, as he saw it, provided the
intellect with the kind of object that could guarantee its
knowledge, for they varied not at all but were permanent,
and permanently self-identical. So that only knowledge
pertaining to the Ideas deserved the name of science; all
else was opinion, shifting and ephemeral. Plato, it may be
said in passing, was quite correct as to the kind of object
the intellect must have, but whether this object must exist
in separation from matter, that is something else again.
Aristotle, for one, did not think so. Though agreeing
that scientific knowledge calls for a principle of stability
and necessity, identified by Plato with the Idea, Aristotle
did not seek this principle in a separate entity but, truer
to experience, found it in material reality itself, namely in
substantial form. Corporeal things, then, are not just mat­
ter; they are matter and form. For all that, however,
Aristotle did not repudiate the doctrine of separate sub­
stances—substances, that is, without any matter whatever.
Moreover, in his theory of knowledge Aristotle is at one
with Plato on the insistence that to be intelligible the
object must be abstracted (taken away, somehow) from
matter. For him as for Plato, the intellect is a spiritual
faculty; directly (as against indirectly) it can only know the
“quiddity” of corporeal things; which is to say, the essence

18
Philosophy of St. Thomas: Metaphysics
abstracted from matter. Consistent, also, with the spirit of
Plato, and indeed implied in the principle of abstraction,
is this other thought of Aristotle’s, that an object is in­
telligible in proportion to its liberation from matter; the
more immaterial it is, the more it is intelligible in itself—
in itself, because not necessarily to every intellect. All of
which St. Thomas will capsule in the assertion that the
foundation, the essential condition, of intellection is im­
materiality.18 As intimated, however, not all immateriality,
which is to say not all abstraction from matter, is of the
same degree. This brings us to the next heading, where, in
particular, the immateriality proper to metaphysics should
be noted.

2. The Three Degrees of Abstraction
Within the complex of speculative science Aristotle
distinguishes three types or degrees of immateriality in the
objects of knowledge and, correlatively, in the intellectual
operations proportioned to the objects. These degrees corre­
spond to the threefold classification of speculative science
into physical, mathematical, and metaphysical, a classifi­
cation traditionally accepted. Now, how does one degree
differ from another? It differs according to the objective
matter or material conditions left behind by the intellect
in the abstractive process, or inversely, according to the
matter and material conditions retained in the definitions
18 St. Thomas, of course, as well as Aristotle knew that immateri­
ality is the condition of all knowledge, sense knowledge included.
For some helpful remarks on the meaning of “immateriality” in this
context the reader may consult the author’s Psychology (Vol. Ill of
the present series), pp. 99-101; trans, by John A. Otto (St. Louis:
B. Herder Book Co., 1956).—[Tr.]

Introduction
19
which govern demonstration in a given science. The de­
tailed analysis of this doctrine rests, however, with psy­
chology or, perhaps more properly, with logic—major
logic, that is, not infrequently identified with epistemology.
We shall therefore content ourselves with a summarization.
On the level of physical science the intellect abstracts
from matter so far as it is the principle of individuation,
hence from individual or signate matter {materia signata);
but matter is retained so far as it is the basis of sensible
qualities. It is therefore called sensible or common matter
{materia sensibilis vel communis). Since qualities, which
are retained, are changeable or mobile, by that very fact
is retained the changeability or mobility of things. In the
second or mathematical degree, abstraction is made of the
aforesaid common sensible matter, but kept under con­
sideration is material substance as quantified, which in the
Aristotelian tradition goes by the name “intelligible mat­
ter” {materia intelligibilis) ,19
In metaphysics, on the other hand, the abstraction is
19 Not that this “matter” is “immaterial,” as the unwary might
erroneously take it from the appellative “intelligible.” However, the
exegesis of the phrase “intelligible matter” would require an histori­
cal excursus that cannot be undertaken here. Suffice it to say that in
the context “intelligible” refers not so much to the intellect as to
the imagination, so that we would not impair, and perhaps improve
the sense of it if we said “imaginable matter,” materia imaginabilis,
i.e. matter as terminating in and known by the imagination, an
inner sense, in contrast to matter as terminating in and known by
the outer sense.
Further elucidations of this notion of “intelligible matter” may
be found in Charles De Koninck’s eminently perceptive article “Ab­
straction from Matter (II),” Laval Théologique et Philosophique,
XVI (1, i960), pp. 63—69.—[Tr.]

20
Philosophy of St. Thomas: Metaphysics
complete; abstracted, therefore, is all matter and motion of
whatever kind. This degree of abstraction takes us into the
realm of the utterly immaterial, which comprises both
spiritual realities (God and the angels) and the primary
concepts of being—being itself and the transcendentals, to
mention the more obvious. The latter, that is, the primary
concepts and the realities corresponding to them are inde­
pendent or separate from matter in the sense that they
need not be realized in corporeal things but are found as
well in incorporeal or spiritual being.20
The special character of metaphysical abstraction will
be pointed out at some length in the next chapter, when
we analyze the notion of being. It is well, though, to antici­
pate a word of caution on the general subject of abstraction,
and on metaphysical abstraction in particular. The intel­
lect, we have said, attains in successive steps the three
degrees of immateriality; but the activity by which it does
this is not of a piece, or uniformly the same, as though
the three steps were mere repetitions of the identical opera­
tion. The three acts of abstraction are not homogeneous,
though comparable—analogous is really the word. To over­
look this is to lapse into superficiality, not to say into gross
misconception. True, the degrees of abstraction have in
common that each is a removal of matter from considera­
tion, but the manner of removal as well as the extent
differs from one degree to the next. In the case of meta­
physics St. Thomas prefers not even to call it abstraction
20 For St. Thomas’ analysis of the degrees of abstraction see In VI
Metaph. lect. i, nos. 1156-1163; In Boet. de Trinitate, q. 5, aa. 1, 3;
Summa theol. la, q. 85, a. 1, ad 2.

Introduction
21
but, more accurately, “separation,” a term he does not
apply to the first and second degree.21
The word “separation” must not, however, lead us
astray in another direction. When, in other words, meta­
physics is said to be the science of the “separate” or, if one
prefers, of the “abstract,” this does not imply that its object
is divorced from real existence but only from the material
conditions of existence. It could not be otherwise. Indeed,
we shall see that the object of metaphysics is eminently real
and concrete; so that far from being out of touch with
reality, the metaphysician is in the full sense of the word
more a realist than any of his fellows in the fraternity of
scholars and scientists. And this is true whether he con­
siders, under the aspect of being, the totality of things mate­
rial and immaterial or whether, sectoring his horizon, he
fixes attention on what is real above all because immaterial
above all: pure spirits, that is, and infinitely above them,
God.
IV. METAPHYSICS AS THE SCIENCE OF BEING
AS BEING

In this, the third aspect which Aristotle’s metaphysics
assumes, the accent is on the universality of the science.
21 Cf. In Boet, de Trinitate, q. 5, a. 3. Also well worth reading in
this connection is Maritain, Existence and the Existent (Doubleday
Image paperback), pp. 37-42, with particular attention to note 14,
on the abstraction proper to metaphysics together with references to
other works of his dealing with the degrees of abstraction. Existence
and the Existent is translated by Lewis Galantiere and Gerald B.
Phelan (Garden City, New York: Doubleday & Company, Inc.,
lTr-]

22
Philosophy of St. Thomas: Metaphysics
There are in philosophy certain notions that run through
all its branches, the most common or universal notions, as
they are called. For each branch to make a study of these
notions would lead to fruitless as well as endless repetition.
Yet they are too important to go unexamined; somewhere
they must be submitted to careful analysis and interpreta­
tion. Logically as well as by general agreement this task
falls to metaphysics, the science universal.
i. Historical Derivation of the Metaphysics of Being
Among the universal notions just referred to is that of
being. In Aristotelian thought, however, this notion is not
simply one of many; it is first and most fundamental, the
one the intellect conceives before all others. What, it may
be asked, moved Aristotle to accord the primacy to the
notion of being? The question is not idle; it has to do with
what is perhaps the most significant adoption in all his
philosophy. And as with other positions adopted by Aris­
totle, this one too had had a considerable history in Greek
thought; so that once again it is in the speculations of his
predecessors that Aristotle finds the direction his own
thought will take.
As far as can be determined, it was Parmenides who first
realized the preeminent value of the notion of being. For a
century or two before him Greek philosophical schools had
concentrated on determining the primordial element, the
ultimate substance of which the physical world could have
been constituted. The answers were many and varied.
Thales held for water, Anaximenes for air, Heraclitus for
fire. Others, going beyond the appearances of things, made
some progress toward a first element or principle that was

Introduction
23
not sense-perceptible, Anaximander, for example, thinking
he had found it in what he called the “indeterminate”
(apeirori), and Pythagoras in number.
Parmenides, next on the scene, was not detained by these
surmisings. In his poem on nature, as a man sure of his
ground, he goes straight to the mark, unerringly showing
the way to being, which he deems the way to truth. Being,
he says, is (esti)—or, perhaps more aptly, exists; moreover,
being is all one, and undivided, and immobile (unchang­
ing) yet corporeal, resembling a vast sphere. But, he con­
tinues, if being is, then nonbeing is the absolute opposite,
an absolute nothing; in a word, it is not—where “not”
means the utter negation of being.22 We may note that the
Parmenidean doctrine of being, if pushed to the limit,
would mean the suppression of real becoming and real
multiplicity in the world; nevertheless, the first founda­
tions of the metaphysics of being are here in the making.
Plato, while not ignoring the Parmenidean doctrine and
the problems it raises, gave the quest of the first principle
a different turn. In his view the ultimate explanation of a
thing lay rather in its end, meaning its perfection or good.
Thus the master Idea, the one that excels all others, is that
of the Good, in which the science of dialectics,23 for him
22 To the uninitiated the assertion that “nonbeing can only mean
utter nothing” is doubtless good sense, when in fact the conse­
quences, alluded to in the text, are rather disastrous. This will be
more fully examined in chapter 6, on act and potency.—[Tr.]
23 “Dialectic” is a chameleon word changing, practically, with
every philosopher (or philosophy). As conceived by Plato, dialectic
is essentially the science of highest principles (bearing on the sub­
sistent Ideas, the only realities worthy of the name); which is far
different from what it means (say) on the lips of Kant or the Marx­
ists or, for that matter, of Aristotle.—Translator’s note.

24
Philosophy of St. Thomas: Metaphysics
the science par excellence, finds its true light and inspira­
tion. Yet even Plato, in the later Dialogues, gives some
indication of having gone beyond this initial position of
his. There, in effect, we find him arguing that something
still higher than the Good is needed, which he identifies as
the One, source of the many. The decisive step in this
direction was not taken, however, until some six hundred
years later when Plotinus, leaving no doubt as to his posi­
tion, categorically declared the One the first principle, and
its contemplation the highest knowledge. In Plato, then,
and in his school, being is a secondary notion, overshadowed
by both the Good and the One: by the Good because as
end it offers, in this view, the higher explanation of things;
by the One because, again in this view, it is a simpler
notion, hence more basic and primary.
Aristotle, countering Plato’s persuasion, stuck to the view
that for the absolutely primary notion of things one had to
go back to Parmenides, back to being; and furthermore, if in
being lay the primary notion, in being lay also the proper
object of the primary science metaphysics. This was no
derogation to the Good and the One; for these notions, too,
belong to every being and are both of them every bit as uni­
versal and scarcely less primary—transcendental they are,
even as being. Absolutely speaking, however, being (to on)
is prior; a thing must be before it can be one or good. Meta­
physics, accordingly, is essentially the science of being.24

2. The Three Conceptions of Metaphysics in One
To define metaphysics as the science of being as being
is at the same time to enunciate its proper object, or in
24 Cf. Text II, “The ‘Subject’ of Metaphysics,” p. 244.

Introduction
25
more adequate terminology, its subject of inquiry—sub­
jectum, as the Schoolmen understand it. With the proper
object as the point of reference it is not difficult, and
logically quite consistent, to integrate the two other con­
ceptions (science of first causes, science of the separate)
with the third (science of being). For, the study of an
object and the study of its causes may well pertain to one
and the same science. This granted, the science of being
as being should also seek out its causes (first causes, hence
science of first causes), among which is God, the most im­
material, hence most separate cause (thereby, science of the
separate). Thus, while there are three possible ways of
viewing metaphysics, they are not exclusive—one implies
the other. But only through one of them is its proper object
formally stated, which is neither first causes nor separate
being, but being as being.25
V. METAPHYSICS AND CRITIQUE OF
KNOWLEDGE

Sooner or later the expositor of St. Thomas, of his meta­
physics especially, must meet the issue that divides him
most sharply from the moderns. Led by its most eminent
representatives modern philosophy takes a wholly different
attitude as regards the object of metaphysics and indeed as
regards the object of human knowledge generally. In the
traditional view the first and immediate object of knowl­
edge is being, the being of external reality. But in the
modern view the first and immediate object is not external
reality but the mind itself, or its thought processes, to use a
25 Cf. St. Thomas, Commentary on the Metaphysics of Aristotle,
Prologue.

2Ó
Philosophy of St. Thomas: Metaphysics
not uncommon turn of speech. This difference in attitude is
frequently epitomized as a transition from the dogmatic
position of the past to the more critical and analytical
stand of the present, or more succinctly still, from realism
to idealism. How this “Copernican Revolution” in philoso­
phy, as it has been called, came about is not now our main
concern; yet some account of it is apposite to the moment,
for it represents a complete volte-face in philosophical
thinking, not least in metaphysics, where, though the name
survive, the old meaning leaves scarcely a trace.
Consider, first, the general trend of medieval philosophy.
Here, by and large, was a philosophy that has since come to
be known as “realist.” The mind, it was admitted without
questioning, was ruled by a world of objects that exist
apart from it and govern its content—“measured the intel­
lect,” in Scholastic idiom. Being, or reality, came first;
thought, corresponding to reality, came second. Interpreted,
this means that what the mind knows directly is reality;
then, upon reflection, its thought of reality. Transposed to
sense it means that when I look at a thing, what I see is the
thing and not my sight of the thing. This is the attitude of
common sense, and both the ancients and medievals as a
whole, accepted it on that basis; it was, I mean, the most
natural and obvious attitude to take—whether this makes
them naive and uncritical we need not inquire. They did
not, however, pretend that the question of the validity of
knowledge was thereby settled. The truth of the matter is
that the so-called objectivity (realism) of knowledge did not
figure prominently in their speculations, since no acknowl­
edged philosopher seriously doubted the common-sense
view. And thus affairs stood until the dawn of modem
philosophy.

Introduction
27
Prophetic of the new order was Descartes. With him, as
with his posterity, the first immediate object of certain, that
is, indubitable knowledge is no longer external reality.
But if not reality, what then? Thought, or the activity of
thought, is adjudged the more immediate experience, hence
the first direct object of knowledge. The effect of this
inversion was to leave the mind cut off from reality.
Descartes, it is true, felt that you had only to invoke his
basic intuition “I think, therefore I am,” and you found
yourself returned to reality. His successors, however, would
not be assured; to them, a return to reality from knowledge
that was not in the first instance moored to reality seemed
highly problematical, and was indeed impossible, the ideal­
ist postulate having seen to that. For, as this postulate
would have it, what you know directly is what goes on in
your mind—external reality, if known at all, is known as an
inference, never as something actually experienced.
Thought, accordingly, lies immured, its contact with out­
side reality irretrievably lost. On this common theme of
primacy of thought over external reality, subjectivists and
idealists of every description fathered forth tractates and
treatises of endless variety. On one thing, though, all
agreed: there could be no true philosophy that was not
based on the idealist postulate.28
Obviously, the supporters of traditional philosophy could
not remain indifferent to this development. Threatened, in
effect, was the whole structure of their philosophy; and
26 Tire Translator has taken the liberty of enlarging somewhat on
the author’s résumé of the “Copernican Revolution” in philosophy.
Nothing was added, however, that was not implicit in the author’s
own remarks. As for the manner in which Thomists have met the
Idealist challenge, this is examined in detail in the subsequent
epistemological (or criteriological) study of being, chapter 3.—[Tr.]

z8
Philosophy of St. Thomas: Metaphysics
thrust upon them was the question: should they persist in
regarding extramental reality as the unexceptionable start­
ing point of philosophy, or should they yield to the mod­
erns, adopting the reflective study of knowledge as their
springboard, after which they would again take their stand
with the metaphysics of realism?
Offhand, there appears no reason why a follower of St.
Thomas should not undertake a critique of knowledge, a
systematically conducted inquiry into its nature and validity,
especially its validity. Not a few eminent Thomists have
done just that. But all attempts are well advised of certain
restrictions. The critique should not be considered the in­
dispensable preliminary to metaphysics, nor be allowed to
supersede metaphysics as the superior wisdom; but above
all it must from the outset avoid the idealist principle of
absolute inferiority, whereby thought is arbitrarily so im­
pounded in the mind as to render direct access to reality
impossible. On these conditions, an epistemology (a cri­
tique of knowledge) according to the mind of St. Thomas
is quite possible and perhaps feasible.
Yet, when all is said, the true embodiment of wisdom
still lies in a metaphysics that is at once realist and critical
(self-critical, that is). St. Thomas states flatly that there is
but one supreme science, and as supreme it does not hand
over the task of justifying or defending its principles to
another; it does it itself. “Metaphysics [sc. itself],” to quote
his own words, “carries the argument to those who deny its
principles.” 27 This science must be grounded in realism,
which is to say in being, assuming, as we do, that being is
the first thing known by the intellect and constitutes its
27 "Metaphysica disputat contra negantem sua principia” (Summa
theol. la, q. i, a. 8).

Introduction
29
proper object. Although it takes its stand on realism, this
science will also be, in fact cannot but be critical (or
criterioligical); for there are difficulties encountered as to
the validity of knowledge, very substantial difficulties, which
must be met by the science itself, there being none higher
to which they can be referred for solution. Granted that the
difficulties in question may be organized into a separate
study, outside the context of metaphysics proper and under
the heading, as is sometimes done, of epistemology or criteriology; nevertheless, there seems more to be gained, and
more logic as well, in conducting the critique of knowledge
within the compass of metaphysics proper. If nothing more,
such a procedure does better to safeguard the unity of meta­
physics; and better kept too will be the autonomy, the
complete self-jurisdiction that belongs to it as first philo­
sophical wisdom. In this, moreover, we have Aristotle’s
precedent, who incorporates a considerable criteriological
section into his metaphysics, in the course of which he
defends the first principles of thought against the sub­
jectivists of his time.28 We, for our part, shall follow
Aristotle’s example, so that after the next chapter, which is
the metaphysical study of being, will follow a criterio­
logical chapter, the critical examination of our knowledge
of being.
VI. THE METAPHYSICAL WORK OF ARISTOTLE
AND ST. THOMAS: PROBLEMS AND PROCEDURE
a) Aristotle’s metaphysical production has given rise to
some important literary problems. The principal one centers
on the formation of the eponymic Metaphysics, a collection
in fourteen books containing his essential thought on first
28 Cf. Metaph. r, chapters 3-8.

30
Philosophy of St. Thomas: Metaphysics
philosophy. This collection, it is commonly realized, did not
originate as a continuous composition, from one time and
one effort. It is rather a compilation of writings, or parts
thereof, which date from various periods of Aristotle’s
career. The present arrangement, moreover, stems not from
himself but from his posthumous editors. For our purpose,
however, it is not necessary, nor would it be feasible, to go
into the literary problem the compilation poses; but we
should at least indicate the basic groupings within the
work as it now stands, since this bit of information is almost
indispensable for intelligent reading of the whole.
Books A, B, r, E. Z, H. 0 (i, 3, 4, 6, 7, 8, 9) constitute a
sufficiently coherent body to be considered, for all practical
purposes, a continuous development. Treated, after some
preliminaries, are the following problems: the object of
metaphysics (being as being, and the things pertaining to
being as being); substance (the fundamental mode of be­
ing); act and potency. Books I and A (10,12) appear to have
been independent compositions, yet in the plan anticipated
by Aristotle they follow logically after the preceding group.
Book I deals with the problem of the one and the many;
Book A, after some recapitulatory chapters, with the primary
substance (the first mover). Books M and N (13,14), though
probably of different date, are closely parallel in content;
both present a searching criticism of the (Pythagorean)
theory of numbers and the (Platonic) theory of Ideas. This
leaves Books a, A, and K (2, 5, 11), which it is difficult to fit
into a pattern with the rest. As to content, Book a (2),
whose authenticity is debated but generally accepted, deals
mainly with the problem of nonregression to infinity; A (5)
is scarcely more than an analytical lexicon, though a very
valuable one, of philosophical notions, pertaining mostly to

Introduction
31
physics and metaphysics; K (11) is a gathering of extracts
from the Physics plus abridgments from B, r, and E of the
Metaphysics.
b) Further complication awaits us in turning to St.
Thomas, whose metaphysical work, on the whole, falls to
two principal deposits.
The first is, of course, his Commentary on Aristotle’s
Metaphysics, the first twelve books, to be exact. Concerning
this Commentary, the opinion has been advanced that St.
Thomas was only clarifying Aristotle’s thought, refraining
his own. The opinion is untenable. In the Commentary St.
Thomas, it must be maintained, was not only spelling out
Aristotle but also philosophizing on his own. What is true
is that the Commentary of its very nature does not escape
the hobbles and hitches of Aristotle’s text, which, while
perhaps sufficiently articulated, yet lacks that perfectly or­
ganic composition one might wish. In any event, the Com­
mentary is not the complete metaphysical thought of St.
Thomas. There are other developments of his on the sub­
ject, more uniquely his own, and these also must be
appreciated before one can see his metaphysics in all its
richness and amplitude.
The second deposit in point is found in his theological
study of God as one (De Deo uno). Here again all is not in
one place, though all is very much of a piece. There is the
ample section in the Summa theologiae,2930
a whole book of
the Contra Gentiles,90 and an impressive array of parallel
passages in various smaller works.31 In these compositions
29 Summa theol. la, qq. 2-26.
30 Contra Gentiles, Book I.
31 The most important of which are the Quaestiones Disputatae
and not a few so-called Opuscula.

32
Philosophy of St. Thomas: Metaphysics
St. Thomas’ thought is expressed more at large than in the
Commentary, and its scope and penetration grow accord­
ingly. But here, on the other hand, it is interwoven with the
fabric of supernatural (as against natural) theology.
St. Thomas may be said to offer a twofold version of
metaphysics: one whose source and methodology is purely
philosophical but whose structure is noticeably grafted and
underdeveloped; the other, more organic, excels in height
and depth but has, for us, the disadvantage of being in­
corporated in theological dissertation. Between the two, we
hasten to add, there is remarkable coherence of doctrine,
albeit the preoccupations and the standpoints are not the
same. In practice, nevertheless, the expositor of St. Thomas’
metaphysics must, to keep his account orderly, make a
choice. Either he adopts the strictly philosophical point of
view and from the being of experience progresses to the
being that is God (as in the Commentary), or he takes the
theological approach, a more synthetic task, according to
which God stands at the beginning of his inquiry and
created being is elucidated throughout as his handiwork
(as, for example, in the Summa Theologiae).
c) Our choice is the former. While not disregarding alto­
gether the invaluable complement of the theological writ­
ings, our study follows the philosophical path of the Meta­
physics and the Commentary. It begins, accordingly, with
the being of immediate experience and advances by degrees
to the being that is God, the natural culmination, it will
appear, of the entire work as well as the keystone that firms
it together. That done, we shall have an adequate view of
St. Thomas’ metaphysics but not, be it said, an exhaustive
one. For such a view, it would be necessary to go consider-

Introduction

33

ably further. The steps of our inquiry would need to be
retraced and the basic positions we have established gone
over again to be propounded a second time, but from the
perspective of the theological treatment of God. The result
would be, so to speak, a downward metaphysics, from God
to creature, in contrast to the upward manner of the present
work. To achieve it, however, would have made a more
formidable task, and a more formidable volume, than lay
to the purpose.

t CHAPTER 2

Being: Metaphysical Study

I. THE STARTING POINT OF METAPHYSICS
t AS Bergson justly remarked, every self-consistent
philosophy starts from an intuition which governs its entire
development. What Bergson was saying, in effect, is that
the object of metaphysical inquiry must be sought in some­
thing first and unconditioned, hence not derived from or
reduced to anything else, while everything reduces to it.
It need hardly be mentioned that unless this fundamental
of a philosophical system is properly identified and properly
defined, there can be no firm grasp of the system.
In the case of St. Thomas there is no doubt what con­
stitutes the root of his system; it is, unmistakably, being,
from the apprehension of which, as from its generative
source, issues every ramification of his metaphysical thought.
St. Thomas, on this point, expresses himself as follows:
“What the intellect first conceives, on the ground that it is
the most known object, is being; and to being it reduces
all its conceptions.” Or, in his Latin,

36
Philosophy of St. Thomas: Metaphysics
Illud autem quod primo intellectus concipit quasi notis­
simum et in quo omnes conceptiones resolvit est ens.1

Thereby he expresses both the universality and the
primacy of being, and of the corresponding notion of be­
ing. Every conception of the mind can, as we have just
heard, be reduced to the notion of being; which implies
that objectively, as well as conceptually, everything is being.
This recognition that everything is being is absolutely
primary; for it is a recognition of the object which, in
itself,2 is most known, that is, first and last and wherever
anything is known.
Still, it is one thing to say that being is the first and most
universal notion, and quite another to catch the full signifi­
cance. There is, to be sure, a common acquaintance with
being, and with the notion of being; but this is to know the
thing but dimly, the seeds of knowledge, not the harvest.
The mature grasp of the factors of being and its notion
calls for minds disciplined to think and rethink philo­
sophically. Nor even then will it all come at once, nor, de
facto, in one generation. It is quite consistent that through
the centuries the human mind has given, and still gives,
much time and effort to the pursuit of being, to see what
lies in this, its first and most universal recognition.
Parmenides, to speak for a moment historically, has
already been mentioned as the first to see clearly that being

1 De Veritate, q. 1. a. 1.
2 “In itself,” because in Scholastic thought what is most knowable
in itself may not be most knowable to a given intellect. Of course,
the being of popular experience is most knowable to the human
intellect as well as in itself; but, as every real student of philosophy
knows (and the author will make abundantly clear), the moment we
crack the surface of being, mystery abounds.—[Tr.]

Being: Metaphysical Study
yy
is primary both on the side of reality and on the side of
thought. But Parmenides bore the tradition of the Physi­
cists, the earliest Greek philosophers of corporeal nature,
who saw scarcely beyond the realm of matter. The tradition
left its mark; for though the Parmenidean being is im­
mobile (changeless) and undivided, it is still nothing more
than the sum total of the world perceived by the senses.
Thus the ontology (science of being) of Parmenides could
not but fail to rise above the corporeal level. Where he
failed, Plato in large measure succeeded, not only, by the
world of Ideas, surmounting the being of sense, but also
restoring to being its multiplicity and becoming. There­
after, by progressive discovery, Aristotle and still later St.
Thomas will both of them strike the true notion of being
—a notion transcendent and analogical.
The notion of being can be traced psychologically as well
as historically; in other words, the unique circumstances in
which the notion of being finds itself appear, perhaps most
readily, when we stop to analyze the content of everything
the mind conceives. For this purpose, any object of thought
will do; it may be this desk before me, or the paper I write
on, or the hand that does the writing, or even the gratifica­
tion that comes over me when my thought meets perfect
expression. I have but to pause to realize that all of these
things or experiences are each of them some kind of being,
and that if neither they nor anything else existed, I would
have nothing to which to attach my thoughts—I would,
indeed, have no thoughts. Even negations and privations
are conceived in reference to being, after the manner of
being. Take away being and no object of thought remains,
and consequently no thought.

38
Philosophy of St. Thomas: Metaphysics
This conclusion is still more compelling from the analysis
of judgment, the second operation of the mind, in which
the act of understanding is completed. Essentially, judg­
ment comprises a subject and another term that determines
or qualifies the subject. The second term may take the
form of a copula followed by a predicate, “the weather is
pleasant,” or it may simply be a verb, “the sun shines.” In
the first case the affirmation of being, that something is, is
clear enough; but even in the second case being is truly
affirmed, though implicitly. A judgment, then, is made in
reference to what is, hence in reference to being. And this
is true of every judgment, affirmative or negative; in one as
in the other, there is an association of two terms telling of
being, saying what it is or what it is not. Thus, in its per­
fective moment as well as in its first moment (first opera­
tion of the mind), every act of thought is determined by
being and fixes on being. And since reality is being, to think
is to form a conception of reality.
In summary: being is the first and most comprehensive
object of thought. Since metaphysics is the science of what
is first and most universal or comprehensive, its object, it
follows, is being. However, the inner content of being, its
metaphysical store, is not thereby told. We have therefore
to probe the matter further.

II. THE METAPHYSICAL NOTION OF BEING
The object of metaphysics, we have said, is being. This
is true—truer, indeed, than appears on the surface. For,
formally speaking, the object of metaphysics is not being
considered as the first object of thought, or being whose
conception is the first notion of the intellect. The object of
metaphysics lies deeper, and to reach it the mind must have

Being: Metaphysical Study
39
recourse to the third degree, the metaphysical degree, of
abstraction, in which being is considered in utter separa­
tion from matter. Only then does the mind apprehend
being formally; only then, that is, does the mind apprehend
being as being, or being as such.3 And this is the object of
metaphysics: being as being, or being as such, prescinded
from this or that mode of it.
The distinction just made is capital; the distinction, I
mean, between being as the object of metaphysics and
being as the first and most universal object of thought. It
takes a while, even a long while, to rise to this distinction,
to the level of metaphysical being. By nature the human
intellect inclines rather to the things of the sensible world;
the utterly immaterial is not its connatural milieu. And
though, as we have seen, it necessarily conceives of every­
thing and hence of sensible things as beings, the being it
first finds in them is not that of metaphysics, unparticu­
larized and matter-free, but that of the physical kind,
particularized and matter-bound. There is, to be sure, in
this common knowledge of sensible things a rudimentary
grasp and awareness of being, but not of being as being,
since in this order of knowledge being is not yet prescinded,
or lifted, from its particularities. In short, the experience of
being that fashions routine thought, and bases even the
sciences, is all on the prephilosophical (i.e. premetaphysical)
level.
Closer, but only closer, to the metaphysical state of
affairs is the concept of being that emerges from its uni­
versalization on the lines of logic. Go back to the familiar
experience of being alluded to a moment ago, the objects
3 It is all the same whether we say “being as formally appre­
hended,” "being as such,” or “being as being.”—[Tr.]

qo
Philosophy of St. Thomas: Metaphysics
of daily acquaintance. It is relatively simple to subsume
these objects under notions that are more and more uni­
versal, as in the Tree of Porphyry, where we find the series:
man, animal, living body, body, substance. As it stands,
however, the series is still open; for there is something still
more comprehensive than substance, namely being, which
comprehends everything and hence closes the series. Thus
the mind has arrived at the logical universal of being. What
it has done is to make a “total” abstraction of being, which
means the abstraction of a logical whole from its inferiors.
The notion thus derived is both most universal and, for that
reason, most undetermined, containing as it does, though
but implicitly, all the differences of being in its endless
variety.
Because of the abstraction involved in its formation, this
generalized notion of being already implies a measure of
philosophical reflection, but the reflection is still pitched
to the level of common understanding. More important, the
notion, because of its universality, is sometimes mistaken
for the formal or metaphysical concept of being which we
shall examine forthwith, a confusion fatal to the grasp of
metaphysics in the traditional sense. That it is a confusion
should be evident, if not from what has gone before, then
from what is to follow; which is by way of saying that the
foregoing considerations have been but preliminary to the
point in hand, the metaphysical notion of being. Having
dwelt on what this notion is not, we are more ready to set
out what it is; and the exposition, in one form or another,
will run the rest of the chapter.4
A serviceable, though far from adequate cue can be found
4 Cf. Text XII, “Concerning Being and Essence,” p. 276.

Being: Metaphysical Study
41
in the very name "being,” which translates the Greek
participial noun to on and its Latin derivative ens.5 Un­
fortunately, the English “being” does not do full justice to
its Greek and Latin counterparts, at least in their meta­
physical connotation. So that instead of “being,” it would
be more exact to translate “the something which is.” This
rendition points at once to two aspects of every being: a
subject or receptor, “the something,” and the actuation or
determination of the subject, indicated by “which is.”
Metaphysically, the first aspect signifies essence (essentia')-,
the second, existence (existentia or esse). Being, accordingly,
is something whose actuality, or proper determination, is
to exist.
The notion of being necessarily implies both aspects.
Essence cannot be conceived except in relation to existence,
and existence in turn calls for determination by essence.
Still, it is possible when thinking of being to give attention
more to one than to the other. This becomes clear when it is
remembered that the word “being” serves both as noun and
as verbal (participial noun). When being, the word, func­
tions or is understood as a noun, its primary reference is to
essence (res); what it says, in effect, is that being is “what
is,” yet not so as to exclude the relation to existence which,
as we have indicated, is ever implied in the notion of being.
As a verbal, on the other hand, being stresses existence; what
it then tells, properly, is that being is “what exists,” but
’French: être, which, as the author remarks in the French text,
were better read as le étant, truly a more felicitous rendition of the
Latin ens; its allusion, however (being “is” or “isses”), is practically
impossible to import into the English being. Perhaps the best we
can do is to hyphenate, i.e. to give it as be-ing, with the thrust on
the second syllable.—Translator’s note.

42
Philosophy of St. Thomas: Metaphysics
again the other aspect is not eliminated, since existence is
always correlative with essence, always the existence of
something. So that, once more, being as we conceive of it
comes forth as a composition of two inseparable aspects,
essence and existence. However, the qualities of this com­
position together with its far-reaching implications are, at
this stage of our study, far from told; we shall see to that
later.®
One point should, however, be cleared up now, namely,
the metaphysical meaning of existence. If the being which
the metaphysician studies includes the aspect of existence,
obviously a thing must be affiliated with existence to come
under the object of metaphysics. But what kind of exist­
ence? Primarily, “being as being” (the object of meta­
physics) signifies existence (esse) in its immediate sense of
real and actual existence: ens actuale, as the expression goes.
But “being as being” is not limited to this; for also to be
included is possible being: ens possibile, i.e. anything ca­
pable of entering the world of concrete existence. Thus,
whatever has been, or is, or will be, or could really be, under
whatever mode or manner, is comprised under the object of
metaphysics, yes even that which is affined to the concrete
order of things by way of privation or negation.7 One thing
only is debarred, the being of reason (ens rationis), which is
the subject of logic. The true being of reason does, no doubt,
6 Namely in chapter 7, Essence and Existence.
7 This view, however, that the being which constitutes the object
of metaphysics includes possible being, is not unanimously held.
See, for example, W. Norris Clarke, S.J., “What Is Really Real?” in
Progress in Philosophy (Philosophical Studies in Honor of the Rev.
erend Charles A. Hart), pp. 61-90; ed. by James A. McWilliams
(Milwaukee: The Bruce Publishing Co., 1955).—[Tr.]

Being: Metaphysical Study
43
have a foundation in reality, yet its very nature is such that
it cannot, as a being of reason, exist in reality; it can only
exist in the mind conceiving it. Consequently, it fails of
inclusion in the metaphysician’s domain, the order of
concrete existence, actual or possible.
This can be schematized:

'being of reason
Being<

actuals.
real being<^
^^object of metaphysics 8
^possible-^
We come then to another side of the problem of being;
but first, a word in passing. Examined so far in the present
chapter have been being and its notion for their meta­
physical meaning according to St. Thomas; that is to say,
examined and defined has been the formal object of meta­
physics. This is only one step in the study of being, but the
step that sets the course for the whole of it. Thus, while
there is indeed more to metaphysics than the settlement
of its formal object, there is nothing more critical; for the
formal object, or rather one’s view of it, shapes the rest of it.
So that in committing ourselves to the view of being that
emerges from the foregoing paragraphs, we have subscribed
to a line of development for the whole of metaphysics. Also,
further reflection, the exact determination of the formal
s

ens rationis

Ens-

ens reale-«<-"actuípe'\,^
, .
possibile—-^objectum metaphysicae

44
Philosophy of St. Thomas: Metaphysics
(metaphysical) notion of being is not only a necessary pre­
liminary to the science, but has always been a thorny
problem for the philosopher. Sooner or later he must ask:
what is being? and sometimes, perhaps often, he has
answered inadequately if not erroneously. Contemporary
thought, on the whole, while exploiting the concrete or
existential side of things, is in general disdainful of essential
being. Tending to the other extreme are philosophers of the
not too distant past by whom being is all but identified, if
not actually so, with essence, to the exclusion or neglect of
existence. For St. Thomas, as we shall have frequent occa­
sion to repeat, being is neither essence alone nor existence
alone but a composite of the two: an essence actuated by
its ultimate perfection, existence.9
III. CONCERNING THE STRUCTURE OF THE
NOTION OF BEING

We have said that the first notion of the intellect is
being, that this notion corresponds to the most basic and
most universal determination of things. We have further
made plain that being comprises two aspects complemen­
tary of each other, essence and existence; whence its defini­
tion as “the something which is.” But though all this is
true, it does not yet touch the real problem concerning the
notion of being. A universal notion, being yet differs from
every other universal notion; it has characteristics all its
own and cannot be dealt with in the common manner of
9 The metaphysician, to be sure, knows of a being that is not a
composite but an identity of essence and existence; yet even this
being is not conceived by us except on the lines of a composite.
—[Tr.]

Being: Metaphysical Study
45
universals. In addition, it labors under an inner tension or
opposition arising from its very structure; which again sets
it apart from every other notion. Hence the problem, for
the metaphysician, concerning the structure of the con­
cept 10 of being. We must take stock of this problem and
then see how St. Thomas and his tradition resolve it.
Recall, as a beginning, the universality of the concept of
being, the most comprehensive notion that can be con­
ceived. Everything in reality, whether actual or possible,
falls under being, hence under the concept of being. How
can the totality of things so diverse be united under one
concept which will include them all, in their diversities as
well as in their identities?
A comparison from logic will show what is at stake. In
logic, a genus is reducible to a species, and vice versa. As­
sume, as illustration, that animals can be classified under
two principal species, vertebrate and invertebrate. All ani­
mals, then, belong to the one genus animal and are divided
into two species by their respective difference, vertebrate
and invertebrate. Thus, in the language of logic, a genus is
reduced or contracted to its various species by the addition
of various specific differences. What makes such a pro­
cedure possible and permissible is that the differences con­
cerned are not actually contained in the genus. Animal as
such (i.e. abstracted from this or that kind) is neither
vertebrate nor invertebrate. The genus, which unites all
animals under one concept, is thus the principle of unity
or identity; and the specific difference, which separates
10 Frankly, there is little difference between “concept” of being
and “notion” of being; we shall, pace the purists, be using the terms
quite indiscriminately.—[Tr.]

46
Philosophy of St. Thomas: Metaphysics
them into classes, the principle of diversification. But the
point is that diversification of the genus is introduced from
the outside, as it were; genus in short does not contain,
actually, the specific differences.
Suppose we now try this maneuver with the notion of
being, and see what happens. Being is multitudinous;
wherever we turn we are surrounded by things, and things
are beings. Yet one concept embraces them all, hence the
concept has a certain unity; its meaning, in other words,
must somehow apply to all the things it covers, else it would
not be, as in fact it is, predicable of all. When, for ex­
ample, I say “this table is,” “this color is,” etc. I mean that
the attribute or circumstance denoted by is occurs, pro­
portionately, in the table, in the color, and indeed in
everything which is. However, I am also cognizant that the
table has not the same mode of existence as the color (the
color is in the table, the table is not in the color). This
diversity inherent to the notion of being is further accentu­
ated when we predicate being of transcendental (in general,
immaterial) realities, and never more so than when it is
predicated of God. God, too, is; but is his being com­
mensurate with lesser realities? And if not, what is it that
will differentiate him from other beings, and these again
from each other? Will it be something that is not being?
Impossible; for what is not being is nothing, and nothing
differentiates nothing. Plainly, the differences of being must
also be some kind of being. But then, how can they still be
differences?
Whatever the solution, one thing is even now clear: the
concept of being cannot be diversified11 in the manner of a
11 I.e. reduced or contracted to classes (species) and subclasses.—
[Tr.]

Being: Metaphysical Study
47
genus, since there are no real differences that are not them­
selves being. The question thus boils down to creating
distinction within a concept without resorting beyond the
concept; or, to importing differences which are somehow
there already. This, precisely, is the problem concerning the
structure of the concept of being, a problem that can lead
astray. For too much stress on the unity of being jeopardizes
the diversity of it and of its concept; and overemphasis of
diversity endangers the unity of it and of its concept. Ulti­
mately, the first path leads to monism, a philosophical
desert such as detained the Eleatics of old; and monism is
only the foreside of pantheism. The second travels to the
other extreme, so much plurification (differentiation) that
being is robbed of community, failing which there fails the
material of any organic thought. How, then, escape this
dilemma, the Sylla and Charybdis of the metaphysical
Odyssey? We escape it through the doctrine of analogy.

IV. THE DOCTRINE OF ANALOGY

Preliminary note: analogy in St. Thomas and his com­
mentators. To give a clear-cut view of the Thomistic teach­
ing on analogy is not an easy thing to do. The considerable
difficulties encountered stem in part from the fact that
nowhere does St. Thomas develop the subject in full, nor in
its own behalf. Thus, while he frequently speaks of analogy,
it is always in application to some other point at issue.
Such as it is, therefore, his teaching lies scattered over
isolated treatments which, even in sum, do not afford a full
exposition, to say nothing of the consequent problem of
reconciling passage with passage so as to get a consistent
body of doctrine. In this matter, then, the mere unraveling
of his text suffices even less than it does elsewhere, and the

48
Philosophy of St. Thomas: Metaphysics
only satisfactory alternative appears to be reconstruction of
his thought, with, of course, the systematic interpretation
that reconstruction supposes.
Interpretive works of this kind have been provided by
the great commentators of St. Thomas. They give a doc­
trine of analogy such as St. Thomas himself might have
given—or did give, in embryo. The prime specimen, with­
out a doubt, is Cajetan’s De Nominum Analogia,12 which
can boast of a veritable school, so great has been its influ­
ence. A fellow commentator of rank, John of St. Thomas,
does little more, in re, than reproduce Cajetan.13 Between
them they have the interpretation of analogy most com­
monly accepted by present-day Thomists. A certain num­
ber, however, professing themselves more faithful to the
letter of St. Thomas, prefer Sylvester of Ferrara, who parts
somewhat from his fellows.14
But whatever their own differences, Thomistic masters
are as one in naming the principal adversary, Duns Scotus,
12 Cajetanus, Thomas de Vio, De nominum analogia et de con­
ceptu entis, edited by N. Zammit, O.P. (Rome: Angelicum, 1934).
English translation and annotation by Edward A. Bushinski, C.S.Sp.
and Henry J. Koren, C.S.Sp., The Analogy of Names and the Con­
cept of Being (Pittsburgh: Duquesne University Press, 1953; Du­
quesne Studies, Philosophical Series, 4).—[Tr.]
13 Joannes a S. Thoma, O.P., Cursus philosophicus thomisticus,
Ila Pars Artis Logicae, q. 13, aa. 3-5; q. 14, aa. 2-3. Nova editio
B. Reiser, O.S.B. (Turin: Marietti, 1948), Vol. I, pp. 481-99,
504-13. English translation available in The Material Logic of John
of St. Thomas; trans, by Yves R. Simon, John J. Glanville, and
G. Donald Elollenhorst (Chicago: The University of Chicago Press,
1955), pp. 152-83, 190-208.—[Tr.]
14 Sylvestris Ferrariensis, Commentaria in Summam Contra Gen­
tiles, I, 34; in Opera Omnia S. Thomae Aquinatis, Leonine Edition
(Rome, 1888- ).—[Tr.]

Being: Metaphysical Study
49
defender of the univocity of being, or at any rate of its
concept. Likewise disputed is Suárez who, in true Suarezian
style, had taken a middle course, thus pleasing neither side.
It is not for an introductory study such as this, however, to
debate one school against another. Below, therefore, is
simply an account of the doctrine of analogy such as, in our
opinion, has the strongest support.15
1. The Meaning of Analogy
Popular as well as scientific thought abounds in the use
of analogy. Things, as a matter of course, are said to be
analogous when they bear some likeness to each other.
15 Books, articles, and monographs which deal, in whole or in
part, with the doctrine of analogy are legion, their number testifying
to the critical role this notion plays in metaphysical speculation.
Among the more readily available works in English are:
Anderson, James F., The Bond of Being (St. Louis: B. Herder
Book Company, 1949).
Garrigou-Lagrange, Reginald, O.P., God: His Existence and His
Nature, Vol. II, in particular pp. 203-224, 246-267, 453-455;
trans, from the 5th French edition by Dom Bede Rose, O.S.B. (St.
Louis: B. Herder Book Company, 1936).
Klubertanz, George P., S.J., St. Thomas Aquinas on Analogy
(Chicago: Loyola University Press, i960). Not the least merit of
Father Klubertanz’s notable work, which appears under tire Series
“Jesuit Studies” and is subtitled “A Textual Analysis and Systematic
Synthesis,” is the carefully assembled Bibliography, which, while not
pretending to be exhaustive of the subject, nevertheless runs through
some ten pages (303-313).
Phelan, Gerald, St. Thomas and Analogy, Marquette Univesrity
Aquinas Lecture, 1941 (Milwaukee: The Marquette University
Press, 1948). An excellent introduction to the subject.
Not in English but now something of a classic is M. T.-L. Penido,
Le rôle de l'analogie en théologie dogmatique; Bibl. Thom. XV,
sect, theol. II (Paris: Vrin, 1931).
These titles have been provided by the Translator.—[Tr.]

50
Philosophy of St. Thomas: Metaphysics
Philosophically speaking, however, not every likeness makes
an analogy, and we shall see presently what is required for
this.
In the Aristotelian scheme, analogy is first viewed under
a theory of general logic, the theory of predication, which
has only to be applied to the notable case of being. St.
Thomas concurs in this approach, for he, too, generally
introduces analogy as a mode of logical predication, the
mode that is neither univocal nor equivocal but in between,
analogical. These distinctions have therefore to be ex­
plained.
“Univocal” describes the term (word and concept) which
is said of things (its inferiors) according to the same mean­
ing in every case. “Equivocal,” on the other hand, desig­
nates a term or word (never a concept) which is applied to
things according to a meaning that is wholly different from
one to the next. Thus, in “Peter is a man” and “Paul is a
man” the term “man” is univocal; there is identity of
meaning. But in “the bark is peeling” and “the bark awoke
me” the term “bark” has obviously two completely differ­
ent meanings. Between complete identity and complete
diversity there is a middle ground, occupied by the “analo­
gous” term (word and concept), which is said of many (its
inferiors) according to a meaning that is partly the same
and partly different in each case. So, in “intellectual vision”
and “bodily vision” the term “vision” is neither univocal
nor equivocal but analogous. On which general topic St.
Thomas expresses himself thus:
It is evident that terms which are used in this way [i.e. ana­
logically] are intermediate between univocal and equivocal
terms. In the case of univocity one term is predicated of differ-

Being: Metaphysical Study
51
ent things according to a meaning [ratio] that is absolutely one
and the same; for example, the term animal, predicated of a
horse and of an ox, signifies a living sensory substance. In the
case of equivocity the same term is predicated of various things
according to totally different meanings, as is evident from the
term dog, predicated both of a constellation and of a certain
species of animal. But in those things which are spoken of in
the way mentioned previously [i.e. analogically], the same term
is predicated of various things according to a meaning that is
partly the same and partly different: different as regards the
different modes of relation, but the same as regards that to
which there is a relation.16
This, then, is our preliminary finding: that analogy is an
intermediate mode of predication, lying between the univocity of a logical universal and the equivocation of certain
terms to which convention assigns disparate meanings. But
this is not the whole of it. Analogy, in its further discrimi­
nation, denotes a relation, an agreement, a proportion—
terms, all, which tell of one or the other aspect. In general,
however, every analogical denomination bespeaks a rela­
tion, or relations, between certain things. And where there
is relation there is community or a common element which,
in the case of analogy, may be considered from two sides:
that of the analogates, that is, the things which are related
to each other, or that of the concept in which the mind
16 In XI Metaph. lect. 3, no. 2197 (Rowan trans. II, 788). Be­
cause of its special relevance it may be well to cite the conclusion of
the above quotation in St. Thomas’ Latin: “In his vero quae prae­
dicto modo dicuntur, idem nomen de diversis praedicatur secundum
rationem partim eamdem, partim diversam. Diversam quidem quan­
tum ad diversos modos relationis. Eamdem vero quantum ad id ad
quod fit relatio.”

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Philosophy of St. Thomas: Metaphysics
seeks to unify the diversity confronting it. In addition,
analogy always implies order of some kind, and order pre­
supposes a unifying principle. So that, in sum, true analogy
requires i)a plurality of things 2)related to each other 3)
according to a certain order and 4)brought together by the
mind under one, unifying concept.

2. Division of Analogy

Both St. Thomas in a much-cited passage17 and Cajetan
in his distinguished work 18 propose a threefold division of
analogy, though not all three in identical terms. Thus, what
St. Thomas calls “analogy according to being but not
according to concept,” Cajetan designates more simply as
“analogy of inequality.” 19 Actually, however, this analogy
by whatever terminology is more properly a case of univocal
predication, except that the concept in question is realized
more perfectly in one thing than in another (hence the
“inequality” of Cajetan). So, in the ancient example, the
generic concept “body” is univocal but realized unequally
in the two species of body: corruptible and incorruptible.
Since, as has already been intimated, being is not predi­
cated univocally, this kind of analogy does not serve in
metaphysics. What is left then are the two basic types:
analogy of attribution (St. Thomas: of proportion) and
analogy of proportionality.
a) Analogy of attribution. This is the analogy about
which Aristotle is most explicit, applying it even to the
17 In I Sent. d. 19, q. 5, a. 2, ad 1.
18 The Analogy of Names, chap. 1.
10 St. Thomas, loc. cit., “analogiam . . . secundum esse et non
secundum intentionem.”

Being: Metaphysical Study
53
special case of being considered as the object of meta­
physics. The unity of the analogous concept stems, in this
case, from the fact that all the analogates (except the
principal) are referred to one and the same term (principal
analogate). Thus, to take the classical example, food, medi­
cine, and complexion are said to be healthy (puristically:
“healthful”) for the reason that food, medicine, and com­
plexion are all related to health, the first two as causing or
contributing to it, the third as indicative of it. Properly
speaking, however, health is found only in the animal
nature.
More precisely, in the analogy of attribution there is
always a primary (or principal) analogate (or analogue),
in which alone the idea, the formality, signified by the
analogous term is intrinsically realized. The other (sec­
ondary) analogates have this formality predicated of them
by mere extrinsic denomination. Health, to come back to
our example, exists formally and intrinsically, i.e. really and
truly, only in the animal. Yet food, medicine, and com­
plexion are rightfully called healthy, but by reason of
some association with health, hence by reason of something
extrinsic to themselves, the health of the animal. Thus, to
put them in order, the characteristics of the analogy of
attribution are these. First, the form (ratio) in question is
one, numerically one, and occurs intrinsically in one analo­
gate only. Second, this form must figure in the definition of
the other analogates. Third, the secondary analogates can­
not be represented by a single concept but only by a
plurality of concepts, among which there is, however, a
certain inter-implication. Finally, it is worth adding that
among the secondary analogates there is also a kind of

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Philosophy of St. Thomas: Metaphysics
gradation, according to their propinquity to the primary
analogue.
b) Analogy of proportionality. It will be remembered
that in the analogy of attribution the (secondary) analogates
are unified by being referred to a single term, the primary
analogue. This marks a basic contrast with the analogy now
under consideration, that of proportionality; for here the
analogates are unified on a different basis, namely by reason
of the proportion they have to each other. Example: in the
order of knowledge we say there is an analogy between see­
ing (bodily vision) and understanding (intellectual vision)
because seeing is to the eye as understanding is to the soul.
We may, as St. Thomas himself does, represent this
analogy in mathematical form, thus:
seeing : eye = understanding : soul

so long as we do not forget that the mathematical repre­
sentation is only an illustration, not to be taken literally.
Metaphysical analogy is not reducible to mathematical
proportion, as should be apparent even from our example,
there being no absolute equality (or identity) between the
two relations in question.
What distinguishes this analogy most sharply from the
analogy of attribution is that the nature or idea (ratio)
signified by the analogous term occurs intrinsically and
formally in each of the analogates. Consequently, even
though there may be a primary analogate, the nature in
view is not, as in attribution, possessed solely by this
analogate. And whereas in attribution analogy is founded on
the extrinsic relation of the secondary analogates to the
primary, in proportionality its foundation, its ontological
basis, lies deeper, consisting in the inner community among

Being: Metaphysical Study
55
things that are yet different and go by different names.
Thus, in our earlier example, “seeing” and “understanding”
are not the same thing, but both are truly and formally acts
of knowledge. Furthermore, since the nature spoken of
exists intrinsically in all the analogates, the definition of
one analogate does not necessarily imply the definition of
the others. I can, for instance, define “seeing” without
reference to “understanding.” On the other hand, because
of their inner community all the analogates can be repre­
sented by a single concept, as, once more, seeing and
understanding by the one concept “act of knowledge.” Any
such concept, however, will not represent the analogates
adequately, nor will it have the perfect unity of the univocal
concept. In the next heading we shall deal expressly with
this matter, the unity of the analogous concept. At the
moment we have a more general item still to report, the
kinds of proportionality.
St. Thomas, in a passage which constitutes the principal
reference for the doctrine of analogy,20 divides propor­
tionality into two kinds: metaphorical and proper. In the
analogy of proper proportionality, which we have explained,
the nature signified by the analogous term is truly and
formally realized in each of the analogates—a point we
emphasized. In metaphorical proportionality, on the other
hand, the nature exists properly (and literally) in one
analogate only, and figuratively (or improperly) in the
others. So, for example, “smiling” is properly said of man
only, but is predicated figuratively of meadow. The analo­
gous notion may, however, be acknowledged to exist in­
trinsically in the meadow as well as in man, since a meadow
is said to be smiling by reason of an intrinsic quality. As
20 De Verit. q. 2, a. 11 c.

$6
Philosophy of St. Thomas: Metaphysics
for terminology, metaphorical analogy may also be called
improper and mixed: improper by contrast to proper, and
mixed because it combines a proper meaning of the analo­
gous notion with one or more improper (i.e. figurative) ones.
Metaphorical analogy is, moreover, part and parcel of daily
speech, and theology itself employs it well and abundantly.
But in metaphysics it has no role; it is not a metaphysical
analogy.
Before passing on now to the next particular, we present
a sketch of analogy which shows the essentials of our discus­
sion to date:

of attribution
(the analogated nature exists intrinsically
and formally in the primary analogate; it is
ANALOGY: attributed to secondary analogates by ex­
properonly.)
trinsic denomination

/
\

(the analogated nature
of proportionality: / formally in all analoexists intrinsically and
gates.) (metaphorical)
\/improper
\ (the analogated nature
' exists intrinsically and
formally in one analo­

gate, intrinsically but im­
properly or figuratively in
the others.)

Being: Metaphysical Study

57

3. Unity and Abstraction of the Analogous Concept

This matter—in particular, the unity of the analogous
concept—is of critical importance. A univocal concept, it
will be recalled, has perfect unity or oneness of meaning.
The analogous concept has no such unity; it is not, as we
have seen, predicated according to a meaning that is abso­
lutely the same in every case, but only partly the same and
therefore partly different, too. Unity of some kind it must,
however, have; otherwise it could not be predicated of
different things according to a meaning that is in some way
identical in each of them. The question of the unity of the
analogous concept thus comes to this: how can a concept
reduce a diversity to unity without excluding diversity alto­
gether? Or, how can a diversity of things be brought under
one concept when that concept must retain the diversity it
seeks to unify? The question, let it be said at once, does not
arise in metaphorical analogy, nor in that of attribution. In
these there is not, as there is in proportionality proper, one
concept which embraces all analogates; there is a plurality
of concepts, specifically, a principal univocal concept which
corresponds to the primary analogue and, for the derivative
analogates, separate concepts but related to the principal
concept. Health is predicated properly and univocally of
animal. But the concept “health” does not cover “healthy
food,” “healthy medicine,” and so on,; these have each its
distinct concept but with a reference to the concept of the
primary analogue.
In the analogy of proportionality, on the other hand,
which is the basic metaphysical analogy, we meet with a
single analogous concept for all the analogates, and this

58
Philosophy of St. Thomas: Metaphysics
because the nature (ratio) expressed by this concept exists
intrinsically and formally in all of them. Thus, substance,
quantity, quality, relation, and the other predicamental
modes are each of them being, formally so, hence come
under the unity of the notion of being. But then arises
the question: how can the unity of a concept be truly main­
tained if it has at the same time to express a diversity, such
as the diversity of being just mentioned?
Repetitious though it be, consider once more the case of
the univocal concept, such as any generic notion. Here the
unity or oneness of meaning is obvious. “Animal,” for ex­
ample, is a generic notion with a clearly determined mean­
ing that applies in one and the same sense to everything of
which it is predicated. The transition from the genus
“animal” to its species is made, as we saw earlier, by adding
the specific differences, which, and this is the point, are not
actually included in the concept “animal.” They are, how­
ever, included potentially, otherwise the generic notion
could not receive them and thus be determined or con­
tracted to its species. In short, the univocal concept is
formally one and potentially divisible, hence potentially
many.
The analogous concept also has unity, and it may also be
diversified; but its unity is not the perfect kind of the uni­
vocal concept and its diversification is not effected by some­
thing from without—a circumstance best seen in the case
of being, for what is not being is nothing. What this means
is that the inferiors, or analogates, comprised under the
analogous concept are intrinsic to it; consequently they are
actually included and actually represented by the one
analogous concept, but only implicitly so, or indistinctly;

Being: Metaphysical Study
59
as when I see a multitude of men, I see them all and know
they are all there without looking at any one of them in
particular.21 The unity of such a concept is not that of an
abstracted form, such as “animal” or “man”; rather, it is a
proportional unity, founded on the real but proportional
likeness which its analogated inferiors have to one another.22
21 In Scholastic phrase the analogous concept is said to be derived
by an abstraction “of confusion,” meaning that the inferiors, while
actually contained or represented in the concept, are not contained
clearly or distinctly or explicitly but “confusedly,” i.e. indistinctly or
implicitly.—[Tr.]
22 What is said in the text applies, of course, to every analogical
concept. But since it is the notion of being that is most important
in metaphysics, further illustration of its proportional unity may be
to the purpose.
A concept, then, has unity if its meaning is unified or one. The
analogous concept can have unity only if its analogates can be some­
how unified under one formality. We have therefore to find that
element in beings in which they are all somehow alike. If, then,
with St. Thomas we define being as “that whose act is existence”
(id cujus actus est esse), we shall have the common element, namely
that in every being there is a relation or proportion of essence to
existence. The concept of being is analogous because the relation of
essence to existence is not identically the same in all beings but only
proportionately the same. For example, existence is not realized in
the same way in substance and accident, but both in substance and
accident existence is proportioned to essence.
Briefly, the proportional unity of the analogous concept of being
simply denotes that in all beings essence and existence are propor­
tional to each other, without specifying any particular mode of
proportion. All beings, accordingly, are alike in that all beings exist
in proportion to their essence; and this is enough to give the notion
of being a unified meaning. But this is not a perfect unity, or a
perfectly unified concept; for then the proportion of essence to
existence should have to be identically the same in all beings, which
is ultimately to make all beings one—the doctrine of monism all
over again. Still, we cannot think of being without drinking, at least

6o
Philosophy of St. Thomas: Metaphysics
To say, then, that the analogous concept is one means
that it is proportionately one; so that its meaning is not
absolutely identical from one inferior to another, but only
proportionately so. That it cannot be absolutely identical
is clear when you remember what the analogous concept
embraces: all the diversities of its inferiors, though but im­
plicitly and indistinctly. Of course, we can pass from this
unified and undifferentiated concept (say) of being to more
distinct concepts, namely by explicit consideration of the
mode corresponding to a given analogate and thus making
our knowledge of the analogate more distinct. But it need
hardly be said that we shall also be passing from the general
implicitly, of the different ways in which this proportion of essence
to existence is realized or realizable. Hence, the notion of being
includes, implicitly yet actually, all the diversities of being.
These remarks presuppose, to be sure, that being (as the text will
shortly declare) is analogous by the analogy of proper proportional­
ity. This analogy consists of a compound proportion, i.e. a propor­
tion of proportions; e.g. 5:10 :: 10:20, etc.—only it must be remem­
bered that the proportional equality of being is not an arithmetical
equality. Now, we cannot think of the proportion 5:10, a proportion
of doubleness, without thinking, at least implicitly, of the innumer­
able pairs of numbers that bear this proportion; indeed, the number
is potentially infinite. Similarly, to repeat a point made above, we
cannot think of the proportion of essence to existence without
thinking, implicitly, of the many ways, the numberless ways, this
proportion is realized or realizable. These infinitely varied propor­
tions constitute the proportionality of being; and to think of the
proportionality is to think, implicitly, of all the members of tire
proportionality. Hence, the notion of being includes, implicitly and
indistinctly yet actually, all the diversities of being; but despite
these diversities, all beings are alike so far as in all of them is realized
the proportion of essence to existence. The concept of being ex­
presses this proportional likeness; hence the proportional unity of
the concept.—[Tr.]

Being: Metaphysical Study
61
analogical concept of the analogate to a particular concept
of the same analogate. So, the concept “being” represents
all being and every mode of being—but none distinctly. We
can make this concept more distinct and explicit by nar­
rowing it, say to substance, or relation, or whatever predica­
ment, even nonpredicament, as God and angels. But we
shall have gone from the universal analogical concept of
being to the far more restricted concept of one particular
kind of being.
Metaphysics leans heavily on the analogous concept of the
kind just analyzed; in fact, all its basic concepts are such.
In this it differs markedly from other sciences, whose proper
concepts are all univocal. This suggests, what is indeed true,
that while metaphysics is by every canon a science, its sci­
entific status is quite distinct, and its methodology will be
similarly individual.
4. Order and Principle in Analogy

We have, to now, left hanging a topical matter on which
the leading commentators of St. Thomas are not in com­
plete agreement, namely whether every analogy requires a
prime analogate. The analogy of attribution, it will be re­
membered, depends for its meaning on the secondary
analogates being referred to a principal analogate, so that
the latter is necessarily involved in the definition of the
former. Of its very nature, then, this analogy implies an
order of things in which there is some first thing as its prin­
ciple, namely the primary analogate. Some authors, reiter­
ating Sylvester of Ferrara, urge the question whether this
characteristic should not be allowed to the analogy of
proportionality as well. Lending considerable favor to the

62
Philosophy of St. Thomas: Metaphysics
suggestion is the fact that St. Thomas, or so it seems, speaks
equivalently of analogical predication and predication
graded according to priority and posteriority (per prius and
per posterius). Every analogy, on this line of thought, would
thus entail an order among its analogates, and if an order,
then a principle or reference point upon which the order
turns; which principle could be none other than a first
analogate concretely determined.
In response, it can scarcely be denied that even in the
analogy of proportionality there is a gradation, an order,
hence some principle of order. But it is a fair question
whether this principle is numerically and concretely one
and thus a veritable first analogate, or whether it is only
proportionately one, a principle of order arrived at through
the assignment of relation among the analogates concerned.
Take the prime example, the case of being, which, as we
shall see, is analogous according to the analogy of propor­
tionality. Can the analogy of being be established without
explicit reference to the first being, that is, without going
beyond the realm of the participated modalites of being?
The answer, it seems to us, is yes; it is possible to conceive
an analogous notion without respect to a first analogate; to
have, in particular, an analogous notion of being which
does not involve explicit reference to per se, or self-existent,
being. But it is clear that such a concept will not be the
final one; the more ultimate structure of the analogical
order, of the order of being in particular, comes to light
only in the measure that the unity of the analogical concept
is grounded on the unity of a first term in reality. The
metaphysics of being, in consequence, is not complete until
created being is seen in its essential dependence on self-

Being: Metaphysical Study
63
existent being, by very nature not dependent. Thus, while
it is possible, in our opinion, to have an analogical concept
of being without the concurrence of a first analogate, that
there is such an analogate is not thereby denied; indeed, on
this point all parties are in the affirmative but differ again
on how it is arrived at, some taking the view that the anal­
ogy of proportionality suffices, others that recourse must
be had to both analogies, proportionality and attribution.
Whatever the answer to that, it should be noted that in
the analogy of attribution the first analogate, which is its
principle of order, can be founded on more than one line
of causality. St. Thomas usually points out three: material,
efficient, and final causality, with the occasional addition
of exemplary, ft is therefore quite normal when for the
same notion or reality there appear several orders, hence
several principles, of analogy. The most notable instance
is, once again, that of being. According to material or sub­
jective causality the order of the modalities of being is based
on their relation to substance, the first and absolute subject.
This is the approach Aristotle adopts in the Metaphysics,
namely the consideration of being as primarily substance.
If, on the other hand, we view being from the standpoint
of extrinsic causality (material or subjective causality is in­
trinsic), the first analogate will not be substance but must
be sought in the being that is the ultimate cause of sub­
stance as w'ell as of all other modalities of being, namely
God, transcendent cause of all created being. This is the
view St. Thomas usually takes, that is, the view of extrinsic
causality, which, it must be admitted, is superior to the one
of Aristotle in the Metaphysics; for in dealing with being
from the standpoint of extrinsic causality we do not con-

Philosophy of St. Thomas: Metaphysics
sider it as subject but as esse, or according to its ultimate
act—a notion to be more fully established in the chapter
on essence and existence.23
V. THE ANALOGY OF BEING

i. The Notion of Being Is an Analogical Notion
From all that has now been said of its structure it should
be obvious that the notion or concept of being, hence being
itself, can only be analogical. Being, as a concept, is mani­
festly not equivocal; no true concept ever is. But even the
word “being” is not equivocal, since (among other things)
it does not convey completely different meanings. Nor is
the concept of being univocal, for it cannot be diversified
or contracted in the manner of a genus. It is therefore ana­
logical, embracing as it does all the modalities of being both
as to their differences and their identities. It is a concept
that is at once differentiated and undifferentiated or unified,
though not, of course, from the same point of view.
That the notion of being (hence being itself) is analog­
ical is so clearly the mind of Aristotle that there can be no
possible doubt of it; indeed, he may be considered the orig­
inal exponent of the thesis. St. Thomas made the teaching
his own, and after him Thomists consistently propounded
and defended it. In opposition are Scotus and his followers.
Scotus, to be sure, does not say that being, or the notion of
being, is a genus; yet he insists that it is a univocal concept,
hence abstracted from its inferiors by a perfect or complete
abstraction and thus containing them only potentially. In
Scotus’ view, therefore, the notion of being has all the ear23 Namely chapter ÿ.

Being: Metaphysical Study
65
marks of a generic concept. The classical and, it would
seem, unanswerable rejoinder to the Scotist position is this:
if the different modalities of being are extrinsic or foreign
to the concept of being, one wonders just what they are.
What, in other words, is there besides being? Also, if the
differences of being are not actually included in the concept
of being, what way is there for them to diversify being ex­
cept in the manner of true specific differences? But this is
to give the concept of being the identity of a genus, with all
the insuperabilities that entails.24
2. Which Type of Analogy Is the Analogy of Being?
Admitted that being and the concept of being are anal­
ogous, we have still to determine the type of analogy that
pertains to being. The determination poses some difficulty,
for in the analogy of being can be found characteristics of
both principal types, i.e. attribution and proper proportion­
ality—metaphorical analogy is obviously ruled out. There
is no doubt, for one thing, that being is analogous by the
analogy of proportionality. What makes it so, it will be
remembered, is that all modes of being are being, formally
and intrinsically. This page of print, its color, its size, these
are each of them being, really and truly, and not merely by
a denomination extrinsic to being, that is not simply by
reason of some extrinsic relation to being, as the relation
of food to health.
Yet there are also aspects of being that serve to bring it
under the analogy of attribution. This, as a matter of fact,
is the viewpoint of Aristotle, according to whom there is a
24 Cf. Text II, “The ‘Subject’ of Metaphysics,” p. 244; Text V,
“Principal Modes of Being,” p. 256.

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Philosophy of St. Thomas: Metaphysics
first analogate, substance, and other modalities of being are
said to “be” by reason of some connection with substance.
“Being,” to quote him directly, “is taken in many senses,
but all of them refer to one source. Some things are said to
be because they are substances, others because they are
affections of substance, still others because they are proc­
esses toward substance, or corruptions or privations or qual­
ities of substance. . . .” 25 St. Thomas himself applies the
analogy of attribution to being from yet another aspect, the
relation of created to uncreated being. Being, in this con­
text, is predicated primarily {per prius) of God, who is selfexistent (per se) being; and it is predicated secondarily {per
posterius) of creatures, who are being only by participation
and by dependence from the being of God.
In the case of being, then,—as for that matter with other
transcendental notions: the one, the true, the good—we
are confronted with a sort of mixed analogy which includes
both proportionality and attribution. Analogy of propor­
tionality is, however, generally admitted by Thomists to
be more primary and more fundamental, at least from the
standpoint of our experience of being. This granted, we
shall say with John of St. Thomas that being is analogous
by an analogy of proportionality which includes, virtually,
an analogy of attribution.
What this means, in effect, is that the concept by which
being is initially grasped is not sharply defined; it is a notion
that admits of further determination, since it comprises
under its proportional unity all the modalities of being
which experience reveals. Upon analysis the modalities are
found to occupy an order, or several orders, and thereby
our concept of being is considerably enhanced. In the area
25 Metaph. r, 1003 b 5 ff.

Being: Metaphysical Study
6y
of material (intrinsic) causality there is one order, founded
on substance, the primary modality in this respect. From
the standpoint of transcendent (extrinsic) causality, whether
efficient, final, or exemplary, there is further order and hier­
archy, founded on the relation of participated to per se
being, or God. Thus, while the concept of being has a
goodly measure of meaning without explicit reference to the
first principle of being, namely God, the full import of the
notion will only be seen when the various modalities of
being are recognized not merely as constituting an order,
but an order that depends on the first being.26
3. The Notion of Being and Metaphysical Method

The conception of being that emerges from the fore­
going analysis leads to some important conclusions as
regards the science of metaphysics. To facilitate our account
of them we shall first recapitulate the main points thus far
established.
1. The notion of being as being is the end product of a
distinct kind of abstraction from matter, which is properly
called “separation” and which is performed on the level of
judgment rather than that of simple apprehension. By this
abstraction being as being is removed by the mind, not from
reality nor from existence—indeed not, for the existent is
the very object of metaphysics—but from all material con­
ditions of existence; which is a far different thing from
removing it from existence.
26 Not all authors explain virtual attribution in the same way. See,
for one, H. Grenier, Thomistic Philosophy, Vol. II, p. 25; trans,
from Cursus Philosophiae (Editio tertia) by J. P. E. O’Hanley
(Charlottetown, Canada: St. Dunstan’s University, 1948).—[Tr.]

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Philosophy of St. Thomas: Metaphysics
2. The notion or concept thus acquired is found, on
analysis, to contain two aspects, essence and existence, the
latter proportioned to and determining, in the sense of
actuating, the former. Hence the recognition: being is
what is.
3. This notion has the structure or constitution of an
analogical concept; which is to say, it makes only imperfect
abstraction from its inferiors. Consequently, the inferiors
are actually retained in the concept of being, though but
implicitly or “in confusion.” And because the inferiors are
actually retained, the unity of this original concept is but a
unity of proportion, hence an imperfect one.27
4. Basically the analogy of being is an analogy of propor­
tionality, a conclusion imposed by the fact that all modes
of being, even to their ultimate differences, are truly being.
But within the multiplicity of these modes there is dis­
coverable a definite order, based on their relation to the
first being. Viewed from this order, being has a further
analogy, that of attribution, by which the analogy of being
is thus rounded out.
5. Because the notion of being transcends any and all
genera of being and extends to all its modes and to their
every difference, this notion is pre-eminently a transcen­
dental one (in the Scholastic sense of the word).
What, then, will be the characteristics of the science
whose object is represented in the notion of being here
recounted? (With that, we return to the conclusions spoken
of above.)
27 For some extended remarks on the meaning of “proportional
unity” see Translator’s note (note 22), p. 59.

Being: Metaphysical Study
69
a) The foremost characteristic is without a doubt its
general orientation, which is decidedly toward the real.
Metaphysics, in this view, begins and ends in reality. To be
sure, it must, like every science, engage in abstraction—a
double abstraction, at that; but this does not mean that it
is cut off from the existent precisely as existent, nor from
any of its modes. On the contrary, the notion of being
signifies concrete reality itself, the whole and every last part
of it. The reason, as we know, is that the notion abstracts
imperfectly from its inferiors, which are therefore actually
retained in it, albeit indistinctly or “in confusion.” 28 Prog­
ress in metaphysical inquiry comes, therefore, not simply
from the abstract analysis of concepts divorced from reality
but rather from the very inspection of reality. Of course,
concepts can be analyzed and systematically presented, as
they generally are in textbooks and special treatises. But it
must not be forgotten that in the Thomist view metaphys­
ical analysis is mostly labor lost unless it stems, not only
initially but continually, from contact with the complexity
of reality itself and with the problems the complexity poses.
If, then, we compare the metaphysics of St. Thomas with
other metaphysical systems that loom large in philosophical
history, we cannot but be impressed by its originality. Thus,
whether it be Plato in antiquity, or Scholastics of the Scotist
and Suarezian tradition, or still later the whole modern
school from Descartes to Hegel; by all of these, being is
generally conceived in the manner of a nature, which is to
say of an essence, dissevered, or nearly so, from existence
and treated as an abstract entity. Ontology, in this line of
thought, tends to become a purely conceptual construction,
28 See Translator’s note (note 21), p. 59.

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Philosophy of St. Thomas: Metaphysics
cut off from reality. Such creations may not improperly be
styled essentialist ontologies. Far different is the considera­
tion of being by St. Thomas, who, while not in the least
neglecting that determination of it which corresponds to its
essence, is ever intent and insistent on that other, that
ultimate determination or actuality of it, its concrete
existence.
b) If next we compare the concept of being—in the
Thomistic sense—with other scientific concepts, those em­
ployed by science in the more current meaning, we find the
former both superior and inferior to the latter. The inferi­
ority, such as it is, lies in the imperfect unity of the concept
of being; the superiority, in its content, which, as implicit,
is inexhaustible.
As we have said, or as much as said, many times over, the
analogical concept is in the idiom of the Schoolman a
“confused,” hence “inadequate” concept—the “confusion,”
to note it again, referring to the way this concept comprises
its inferiors, namely indistinctly or in wholesale fashion. A
concept of this sort does indeed deliver its inferiors to the
mind, but not “adequately,” not perfectly. Since the con­
cept of being is analogical, what the mind thereby knows
it knows inadequately and thus imperfectly; and never is
this inadequacy more acute than when we apply the con­
cept to the transcendent being of God, whose proper mode
of existence escapes us altogether. Unlike metaphysics,
other sciences operate with univocal concepts, which pro­
vide knowledge compounded of genera and specific differ­
ences, knowledge which, in itself if not always in the
knower, is precise and distinct. On this score, then, and to
this extent these sciences have the edge over metaphysics.

Being: Metaphysical Study
71
But the advantage is, as we have said, not all to one side.
There are depths and dimensions of being not reached by
the empirical method. Here metaphysics excels; for the
metaphysical notion of being, and other analogical notions
it employs, cut deeper and wider than the more familiar
scientific notions, and together provide the mind with the
wherewithal to discover areas of reality unknown and un­
knowable by the particular sciences. By these notions, to
mention the prime instance, it is possible to gain some
knowledge, however imperfect, of the very first principle of
all being, even of God. Accordingly, by the method of
analogy, the method proper to metaphysics, we have the
possibility of an authentic science of theology. It is for the
theologian, however, to spell out the role of the method in
his science. Suffice it, then, to have called attention both
to its limitations and to its real merits.
As before in regard to the orientation of St. Thomas’
metaphysics, so now in the matter of its method comparison
suggests itself with the famed essentialist philosophies of
the past. And again we find marked differences. As by a
natural propensity, every metaphysics of essentialist cast
tends to become a rigid system, its whole development
worked out deductively. Though not all the philosophers
mentioned and alluded to previously display this tendency
to perfection, it is no exaggeration to say that all of them
yielded more or less to its attraction. Both Plato and Des­
cartes give evidence of having been captivated by its prom­
ise, at least if the former’s fascination for the dialectic (the
method of the Dialogues) and the latter’s dream of uni­
versalizing the mathematical method are any criterion. The
consummation, however, of the deductive method is to be

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Philosophy of St. Thomas: Metaphysics
seen in the Ethica of Spinoza and the Encyclopedia of
Hegel. With them the expectation others had nourished is
realized, the dream come true; or so it seemed. To derive
everything by deductive reasoning from one first principle,
that was the great passion; and both Hegel and Spinoza
pursued it to the hilt.
St. Thomas, it need hardly be said, studiously avoids such
a course. To be sure, his metaphysical universe is not less
characterized by order and hierarchy than the universe of
these more recent philosophers; and with him, too, reason
governs every stroke of the metaphysical pen. But, presided
over by the analogical method, his thought is far more
tempered to the exigencies of reality in all its diversity.
There is in it room for all that is, and all in its place, yet
no being suffers violence to its nature. Order there is, yes,
but pure construction, no. Indeed, if it is part of the wise
man to give the order of things, sapientis est ordinare, then
true metaphysical wisdom is precisely a work of order. And
this the metaphysical work of St. Thomas is, a work of
order—the veritable order of things.

t CHAPTER 3

Being: Crùerwlogical Study

t THE object of metaphysics is being, which is to
say “that whose act is to exist (esse).” But being is also the
object of our intellect. Thus, a Thomist epistemology be­
gins with this fundamental: that the object of metaphysics
corresponds to the object of the intellect. To accept this
proposition is to take one’s stand on the side of what has
come to be known as philosophical realism. The meta­
physics of St. Thomas, as for that matter almost all the
great systems of antiquity, is a realist metaphysics. In a
realist world the intellect meets things existing independ­
ently of it but which, in being known, measure and deter­
mine it. More simply, in a realist world there are things
and we can know them.1
This thesis—that the mind knows things other than
itself, or that the intellect is measured and determined by
its object, and not vice versa—this is axiomatic in a realist
1 To be sure, there is an intellect which is not measured or de­
termined by things but measures and determines them, namely the
divine; and even the human intellect, in the practical order, is to
some extent the measure of things.—[Tr.]

74
Philosophy of St. Thomas: Metaphysics
philosophy. It is also in accord with the deepest instinct of
the human mind; we have, and we cannot escape, the im­
pression that we know things “out there,” apart from us
and our minds, and that merely to know them makes no
difference—to things. And yet from the beginning or nearly
so, philosophy has had to contend, within its own ranks,
with such as questioned or denied the validity of this funda­
mental experience. Aristotle had already to cope with them,
as when he was impelled to defend the very principle on
which all certitude rests, that of contradiction (or noncon­
tradiction); this had come under fire from the Sophists, the
“subjectivist phenomenalists” of the time. Later came the
Skeptics, who admitted nothing to be true, devising to their
purpose no end of specious arguments.
As for modern thought, it has consistently bent its efforts
against realism, and this among its leading representatives,
Descartes being but the first of many. Inevitably, the renuntiation of realism in knowledge carried over to meta­
physics, so that pitted against traditional metaphysics,
which rested on the premise that being is prior to and de­
termines thought, were now various systems which stood
on the primacy of thought over being, which is to say, on
the general assumption that what we know first and last
and always is a thought, never a thing.
The epistemological problem thus lies at the heart of
modem (if not contemporary) philosophy. Nothing else has
so preoccupied it, and again the question comes up to
which we addressed ourselves briefly in the introductory
chapter: Can metaphysics be solidly established without
first inquiring into the validity of human knowledge? We
thought it not only possible but that the normal life of the

Being: Criteriological Study
77
intellect indicates and justifies such a procedure. This
granted, it should nevertheless be evident that philosophical
positions as important as the ones adverted to above cannot
be simply ignored. Besides, the question of human knowl­
edge poses serious problems to the realist as well as to the
nonrealist or idealist. Accordingly, having but touched on
it in our introductory chapter, we shall now make a more
extensive study of the problem of knowledge, more often
and perhaps more formally named the “critical problem.”
In this, as indicated, we have the precedent of Aristotle, who
also considers the arguments that had been raised against
the validity of knowledge, and right after he has set forth
the object of metaphysics.
The discussion to follow will deal only with the funda­
mental aspects of the problem at hand. Primarily, these are
1) the realism, or objectivity, of the first object of the in­
tellect and 2) the validity of the principles, commonly
called first, which flow immediately from the first object.
Before discussing these cardinal points, however, it will be
necessary to trace the critical problem to its roots and to
attend to the difficulties, real or alleged, which begot it.
Altogether, then, we have four principal headings:
I.
II.
III.
IV.

Critique of Realism
Starting Point of a Thomist Epistemology
Concerning the Foundation of Realism
First Principles
I. CRITIQUE OF REALISM

If realism is the doctrine that we have true and direct
knowledge of an objective world, then the opponents of

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Philosophy of St. Thomas: Metaphysics
realism are those who deny this knowledge. Their grounds
for denial are many and varied, but mostly the case against
realism centers on three themes.

First Theme: Objections of the Skeptics

These objections constituted the brunt of the attack
against realism in ancient thought; but modern philosophy,
too, notably in Descartes and his successors, has never
wearied exploiting them. These objections primarily are
appeals to the fact of error and deception in human knowl­
edge, a fact of which the skeptic has at all times made much
capital. Every occurrence thereof is for him an argument
against the trustworthiness of man’s cognitive faculties. If
the senses, not to say the intellect, deceive you once, they
can deceive you forever. This, in essence, is his thesis.2
Perhaps no one in modem times has developed this
theme more relentlessly than Descartes.3 He begins by ques­
tioning the reliability of the senses. Experience, he says, is
witness that the senses sometimes deceive me; conse­
quently, it would seem the better part of prudence not to
trust them unreservedly. Even those sensations which, be­
cause of their intensity or immediacy, convey the strongest
2 In a sense the skeptic is right; if the senses could deceive us even
once in regard to their proper object, we should indeed never know
when to trust them. Hence the importance of the traditional three­
fold distinction of sensibles: proper, common, and incidental (per
accidens).—[Tr.]
3 See the locus classicus in the Meditations, I (“Of the Things on
Which We May Doubt”); trans, by John Veitch (New York:
Tudor Publishing Co., 1901). There are more recent translations,
but Professor Veitch’s still does it as well as any.—[Tr.]

Being: Criteriological Study
77
impression of objective reality must be held suspect; for in
many a dream I have had similar impressions, only to wake
and find them illusions. Nor is the taint of error confined to
the senses. Reason itself is affected, so as to lie under de­
ception even in mathematics; an assertion the more remark­
able that it comes from the man who honored mathematics
above all human wisdom. Yet this is outdone when Des­
cartes, at the height of his critical mood, entertains the
supposition that for all we know we are under the spell of
an evil genius, of some deceiving god, to the effect that we
labor under irremediable illusion in matters, even, re­
garded as most certain.
For all his doubting, however, Descartes did not succumb
to skepticism. The way out, he felt, had been ensured by
withholding doubt from the first recognitions of the intel­
lect, foremost from the Cogito; for, if thought, then a
thinker whose existence was thus unquestionable. From this
bridgehead he would launch the general recovery of human
knowledge and get on with the constructive side of his
philosophy. But whether this strategy saved the situation
for Descartes is something else again. More to the immedi­
ate purpose is the skeptic’s conjuring up of errors of knowl­
edge to prove that the mind (the senses included) is
delivered to doubt. If, to repeat, I have been deceived
before, and that in my most confident moment, what pos­
sible assurance is there that I am not now deceived, now
and forevermore? Error, in short, is an incontestable fact.
And since it is, does not all knowledge lie discredited? The
question is the skeptic’s and, with him, is not rhetorical.
Our answer comes later in the chapter.

y8

Philosophy of St. Thomas: Metaphysics

Second Theme: Immanence of Knowledge4
It is also contended by idealists generally that realism
rests on a supposition that will not stand stubborn analysis.
To illustrate the contention we may turn to the French
philosopher Hamelin, a typical idealist.® The basis of real­
ism, according to this critic of it, is the duality of “being
that is thought” and “being that thinks,” 6 in other words,
the duality of subject and object. On this supposition, to
think (or to have an idea) could only mean that there is in
the one (being that thinks) an image or representation of
a real attribute possessed by the other (being that is
thought). Essentially, then, knowledge would consist in
having a double of reality in the mind. Now, this manner
of regarding it goes back to simple folk, who are not given
to questioning such matters; whereas critical reflection will
show it to be a pure absurdity, on a par with the ridiculous
assertion that an image or representation is a picture inside
the mind of something outside the mind—as though one
could attain or even speak of something outside the mind.7
4 Refers to the fact that knowledge is an immanent activity as
opposed to transitive action. More specifically, immanence of knowl­
edge means that to be known a thing must somehow be in the mind;
from which the idealist concludes that the mind can only know
itself or its ideas, and cannot get outside itself, so to speak, to lay
hold of the external object—if indeed there is such an object. Some
idealists question even this.—[Tr.]
6 See Hamelin, O., Essai sur les éléments principaux de la repré­
sentation (Paris: Alcan, 1907, First Edition).
6 French: l’être pensé et l’être pensant; which captures the idea
rather more neatly than can be done in translation.—[Tr.]
7 This is typical idealist stock-in-trade—namely that it makes no
sense to speak of knowing something “outside” the mind. Cf. note
4—[Tr.]

Being: Criteriological Study
79
In a word, thought is at once subject and object, and there
is no substance to the naive disjunction of thinker and
thing thought.
But that is not all. Realism (continues Hamelin) stultifies
itself quite as much as another ground, the origin of ideas.
If, as in realism, ideas must originate from an object which
is not the subject, this could only be explained through a
kind of transitive causality, that is, through the transmission
of species or qualities from the object to the mind. In this
conception, it is as though the object literally sent out fac­
similes of itself, which then traveled to the mind—a grossly
materialistic explanation of knowledge which had made its
way into philosophy as far back as Democritus and Epicurus.
Happily, it was laid to rest for good by Descartes, and with
it went the “winged species” of the Scholastics. Nor are
matters improved by adopting the perceptionists’ tactic of
eliminating every intermediary between thought and reality.
This avoids the absurdity of darting images, only to fall into
the mystery of an unsubstantiated immediacy.
To put it squarely, there is no overcoming the difficulties
of realism, and the best advice would be to give up the
chimerical enterprise of trying to make good the primitive
notion that thought involves a duality of thing and thought,
or that what is represented in the mind has a counterpart
outside the mind. The fact is that the represented is not
outside the representation. Etymologically, perhaps, the
representation argues a subject and object having each an
existence apart from it; the real state of affairs, however, is
quite the opposite. The very representation is both object
and subject. (But this would make it reality itself; which is

8o
Philosophy of St. Thomas: Metaphysics
precisely what Hamelin claims for it.) The representation
is being, and being is the representation.8
So much, then, for Hamelin on realism and its alterna­
tive, a typical idealism.
Third Theme: Activity of Knowledge

Opponents of realism feel themselves further justified in
the role which the mind, they are sure, exercises in the pro­
duction of knowledge, a role far different from what realists
would have us believe. For, do not the latter regard the
mind as a purely passive power, inert before an external
object which presumably acts upon it? Yet witness Kant,
who testifies that the understanding,9 far from being intui­
tive (a passive spectator) is essentially active and by nature
engaged in synthesizing the presentations of sense. More
emphatic still are Fichte and Hegel who, pursuing this
Kantian premise to the finish, emerge with the absolute
idealism in which the mind is cast as pure activity, absolute
and unconditioned. Here, then, we have the self that is
self-posited, nothing whatever being presupposed—to the
self.
Proponents of these bold idealist conceptions do not
want for what they feel to be solid arguments. Much is
made, to cite a prime example, of certain features of scien­
tific thought. Advances in this area are to all appearances in
direct proportion to the mind’s ability to project its own
8 Thus, Hamelin does not shrink from pursuing the idealist
premise to its logical conclusion; for if the mind can know only
itself or its ideas, from that it is but a short step to the contention
that ideas are the only existents (at least for tire mind). Hence his
dictum that “the representation is being, and being is the repre­
sentation —[Tr.]
9 In general, Kant’s word for mind.—[Tr.]

Being: Criteriological Study
81
object (thus the argument). Nowhere is this more evident
than in mathematics. The figures, symbols, and numbers
which are studied are first constituted through an activity—
a construction, summation, or calculation—which the mind
clearly recognizes to be its own. Indeed, the mind is capable
of mathematical determinations—be they quantitative, spa­
tial, or numerical—which it cannot visualize to itself, such
is its fecundity in this regard. Much the same state of affairs
is seen in the experimental sciences. You will come across
in an experiment only what the mind has first brought to
it by way of hypothesis or directive idea. And if we go from
hypotheses to general theories, in which the knowledge
science has attained at a given moment is epitomized, there
again we cannot but marvel at the creative fecundity of the
human intellect. All of which leads to the one conclusion:
in the mathematical as in the scientific endeavor, what
governs the working of the human mind is the idea pure
and simple, free of all determination from without.
Further evidence that the mind constructs its object is
found by idealists in the intellectual judgment, by common
accord the perfective moment of the intellectual process. A
judgment, at least a necessary one, expresses a relation which
cannot possibly have been got in experience. Here, as Kant
remarked apropos of the a priori judgment, the sole deter­
mining factor is the mind. Or, if you prefer Brunschvieg,
the exteriority which trails the mind’s judicative operation
is not an exteriority at all but stems from an inborn pro­
clivity of the thinking self. It is as though the mind, by
nature denied its external object, affirmed it with a ven­
geance; idle protest, however, which proves that the mind
has, not an external object, only the necessity to assume it.
Finally, there is the argument that realism—by its doc-

82
Philosophy of St. Thomas: Metaphysics
trine that knowledge is determined by the external object—
destroys or impairs the autonomy which is part and parcel
of the mind’s essential vitality. Materialism, which places a
necessity upon every event, is obviously incompatible with
the untrammeled spontaneity that marks the autonomous
self. But realism comes under the like indictment, so far as
it maintains the mind’s initial dependence upon the ex­
ternal object. Allow this, and never are you truly free. Only
in idealism, which dispenses with the external object, can
the human person be assured of the dignity which must be
claimed for it.
To sum up (for the idealists). All the aforesaid arguments,
and many more besides, support but one verdict: that the
human mind is all activity, free and self-determining, with
not the merest dependence upon an assumedly transsub­
jective object.

II. STARTING POINT OF A THOMIST
EPISTEMOLOGY
Historically, as is well known, the course of philosophical
thought was mostly along the natural line of realism. Knowl­
edge, it seemed obvious, began with external objects which,
however one explained it, determined thought. In the fore­
going paragraphs we have heard various criticisms of this
position. Are these criticisms compelling? Do they render
untenable the historically prior ground of realism? If so, we
must abandon the habit of thinking that knowledge begins
with being, extramental being. In its stead we shall have to
adopt the idealist principle that the starting point lies
within, in thought alone, as exemplified in the Cogito of
Descartes or, most extreme, in the unconditioned positing

Being: Criteriological Study
83
of the self, advocated by idealism such as Fichte’s. Thus the
issue is met. Will it be realism or must it be idealism? The
validity (or invalidity) of the idealist case will tell.

1. General Appraisal of the Skeptic and
Idealist Criticism
Skeptics and idealists allege facts of experience in support
of their criticism against realism. On the whole, realists do
not question their facts, but they do challenge their con­
clusions. Accordingly, we shall indicate the general line of
defense against their pleadings.
a) Objections of the skeptics. These, as we have seen,
played on the undeniable fact of error. Sometimes we are
deceived; we think this but the truth is that. Does it follow
that we are always in error, or that the human mind is
constitutionally incapable of arriving at truth? Skeptics
have said yes; if once deceived, I am always deceived. But
is the consequent necessary? or is it not rather an obvious
sophism? Besides, error or being deceived could have no
meaning unless I knew what is meant by truth or not being
deceived. But most of all, if I am always deceived, then why
not in the announcement of this belief? So that complete
skepticism, as Aristotle had pointed out, is self-devouring.
To be consistent the unrelenting doubter must not say a
word nor even make the merest sign; which, to speak in
Aristotle’s vein, equates him with the vegetable. Granted
that error visits the mind, we are not thereby enslaved to
skepticism. But we are reminded to search out the real
nature of truth and its opposite, error, and to find the
means for discriminating the one from the other. Error, in
short, calls for criteriology; that and nothing more.
b) Immanence of knowledge. It is impossible, the realist

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Philosophy of St. Thomas: Metaphysics
is told, that knowledge bring about a union of two things
which exist in separation from each other. Knowledge is an
immanent activity, immanent to the thinking subject.
Hence, what I think must be in my thought, and what is
not in thought is unthinkable. These and similar expressions
are standard weapons in the idealist arsenal, and as a mat­
ter of fact there is a sense in which they are true. The
idealist, however, construes them in a way to give a com­
pletely false impression of realism. In sound realism there
is no question, as idealists imagine, of throwing a bridge
between two separate and opposite worlds, between thought
and the thing in itself—Ding-an-sich, in the Kantian
phrase. The union of thing and thought is a primary datum,
something given, not contrived. When a thing is known
it is by that very fact present and related to the mind, and
in this sense it is quite true that what is not in thought is
unthinkable. The problem for the realist, then, is not
whether the external object links with the mind but how,
or by what agency, it does so.
Idealists object that the alleged union of mind and reality
rests upon impossible ground; thought, it is said, would have
to emerge from its immanence so as to lay hold of things.
To depict the matter thus implies a grossly materialist view
of immanence or inferiority. Why, in other words, cannot
activity be immanent and still point to something transimmanent? To say that the ideas which make up my think­
ing are anchored in the mind proves nothing; for while this
is undoubtedly true, there is also the very real impression
that through them I am in touch with an external world,
a world exterior to my consciousness. Admittedly, there
would be an element of mystery in this commerce between

Being: Criteriological Study
85
the inner and outer world. But not a little mysterious, also,
is that anyone should bar the possibility of it, unexamined
or in principle.10
c) Activity of knowledge. Not only in the elaboration of
scientific thought but even in its simplest operations the
human mind is active, in fact creative. No one denies this.
But what follows from it? That the mind all alone produces
its object? Or that in its activity it is not at all conditioned
by something other than itself? The facts of the matter
point the other way. Knowledge, as even rude analysis at­
tests, involves passivity as well as activity. And if, in one
respect, the object of knowledge appears to be of the mind’s
making, it also gives many indications of being just the
opposite, something given, not made; in fact, the aspect of
givenness is the prime impression.
In any event, the complex of knowledge can stand far
closer examination than it sometimes receives, even from
philosophers. So, for example, it is by no means self-evident
that the mind alone is responsible for the determination,
that is, for the structure of the object of knowledge, nor
that knowledge is solely activity rather than a concurrence
of activity and passivity. To slight one or the other aspect
distorts the whole picture. Thus, to say in the Kantian
fashion that the understanding is a power of a priori syn­
thesis may have some justification, but it tells us next to
10 For an exposé of the idealist fallacy (particularly of the postu­
late that the mind can know only its ideas, and of the so-called
“ego-centric predicament” on which the postulate rests), see Celes­
tine N. Bittie, O.F.M.Cap., Reality and the Mind, chapter 9,
“Fallacy of Idealism” (Milwaukee: The Bruce Publishing Company,
1936; Twelfth Printing, 1953). It is perhaps no exaggeration to say
that this is the finest chapter Father Bittie has ever written.—[Tr.]

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Philosophy of St. Thomas: Metaphysics
nothing of those elements (data, if you will) of the synthesis
which present themselves ready-made. Experienced reality
is more, and more complex, than is allowed to meet the
Kantian mind.
As for that other side of the question, the idealist’s dedi­
cation to the autonomous self, his prepossession with the
freedom or emancipation which he regards as the very
sustenance of the mind,—all this can be given its proper
place without having to deny in principle every dependence
of this selfsame mind. There may be a mind or self which
enjoys perfect autonomy, but there is no indication that it
must be ours. On the contrary, the self we experience tells,
not of clear and uninhibited autonomy, but of much in­
volvement with what is or seems non-self.
All in all, skeptics and idealists have case enough to
command a hearing. Truth and error, immanence and
transcendence, activity and passivity: these are questions
for any theory of knowledge. But the particulars adduced
by skeptics and idealists do not compel us to abandon
realism in principle, as though to be ruled out even as a
possibility; nor do they prove that being is reducible to
thought. In short, realism does not thereby stand convicted;
after the arguments heard above, its possibility (to say no
more) as a starting point for knowledge still survives. In­
deed, the tables may be turned to ask whether any other
possibility exists. And this brings us to the next heading, a
review of how some recent Thomists would resolve the
problem of knowledge.
2. Some Attempts Toward a Critical Thomist Realism

Within recent decades a number of Thomist philos­
ophers have bent their efforts to a critical theory of knowl-

Being: Criteriological Study
8y
edge which, while expected to culminate in realism, would
not postulate it at the outset. Initially, a sort of neutral
ground is proposed on which both realists and idealists could
agree, in the hope they might still find themselves at one at
the end of their respective roads.
Obviously, the mutually acceptable point of departure
could not be in external reality; it must therefore be in the
realm of the mind, a mental experience that is absolutely
first in the order of reflective thinking. Such is the Cogito
of Descartes, but with a proviso. For, according to these
Thomists the Cogito admits of a preliminary moment
which prescinds from the question whether (as idealists
maintain) it commits the mind to an interiority from which
there is no escape or whether (as the same Thomists an­
ticipate) it can unlock for the mind the door to external
reality. I think (so the Cogito), and it is impossible to doubt
that I think when I am actually thinking. At this point,
however, I do not know, rather do not care to know, what
my thinking ultimately implies—possibly an external world.
This I shall know only later, after the analyses which will
tell me the import of thinking, its eventual referent.
Briefly, the starting point is the fact of thought pure and
simple; then by reflection I inquire after the meaning, the
full implication, of the act of thinking.
One of the more earnest efforts in this direction comes
from the much-respected Roland-Gosselin, who states his
initial position as follows: “From the standpoint of critical
reflection the study of the mind rests squarely on the fact
that the act of thinking can grasp itself immediately in
self-consciousness. In the act of reflection there is perfect
homogeneity, that is, identity of knower and known, and
the identity is immediately evident, so that no subsequent

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Philosophy of St. Thomas: Metaphysics
reflection upon this first reflection can throw it into doubt
or obscurity. Here, then, in the initial act of reflection re­
vealing the identity of knower and known, is an absolute
point of departure because it is first an absolute point of
return, the ultimate turn-back of the mind upon itself.” 11
Thereby, it is believed, is established the sought-for initial
contact with idealism, without as yet any commitment as
to the outcome of the stand agreed upon. “Like idealism,”
to quote him further, “we shall begin by considering first
of all the operation of the mind, specifically the judgment,
and simply as a factual relation between a subject and
object. .. . And why begin thus? Because there is no reason
that we should obligingly abandon to idealists the advan­
tage of a solid position, of an unassailable base of opera­
tion.” 12
But is it unassailable? Or, perhaps more to the immediate
purpose, does it have any support in St. Thomas, who reg­
ularly develops his thought from the supposition of realism?
But at least on one occasion, we are told, he cleared the
way to the kind of philosophical reflection that would base
everything on the awareness we have of our intellectual
activity. A passage in De Veritate has often been so inter­
preted, one which Msgr. Noël13 does not hesitate to match
with portions both of Descartes’ Regulae and Kant’s First
Preface to his Critique of Pure Reason, namely, where these
philosophers urge a general critique, styled on the reflec11 Roland-Gosselin, M.D., O.P., Essai d’une étude critique de la
connaissance, p. n (Paris: Vrin, 1932. Bibl. Thom., XVIII). Trans­
lation mine.—[Tr.]
12 Ibid. p. 35.
13 Noël, L.,Notes d’épistémologie thomiste, pp. 59-60 (Louvain:
Institut Supérieur, 1925).

Being: Criteriological Study
89
tive (introspective) method, of our faculties of knowledge.
The passage in question is this:
Truth ... is in the intellect as a consequence of the act of
the intellect and as known by the intellect. Truth follows the
operation of the intellect inasmuch as it belongs to the intellect
to judge about a thing as it is. And truth is known by the intel­
lect in view of the fact that the intellect reflects upon its act
—not merely as knowing its own act, but as knowing the pro­
portion of its act to the thing.14

St. Thomas goes on to specify that this proportion cannot
be known without knowing the nature of the act, nor the
nature of the act without knowing the nature of its prin­
ciple, the intellect, “of whose nature it is to be conformed
to things.” 18 Then follows the (reputedly) crucial conclu­
sion, namely, that it is by an act of reflective knowledge
that the intellect attains truth.
Far be it from us to discount the significance of this
passage, which (whatever else be said of it) states very
exactly how the intellect arrives at awareness of the truth
value of its act. To see it, however, as inviting a reflective
epistemology, such as now under view, that would seem
to be overdoing the sense of it. Actually, those who stand
on immediate realism without first resorting to a critique
of the mind’s activity could also claim support from the
passage. The fact of the matter is, however, that when
writing these words St. Thomas was not thinking of the
kind of epistemological issue on which he is here sum­
moned to testify.
14 De Vent. q. 1. a. 9; trans, by Robert W. Mulligan, S.J., Truth,
Vol. I (Chicago: Henry Regnery Company, 1952).
15 “in cujus natura est ut rebus conformetur” (ibid.).

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Philosophy of St. Thomas: Metaphysics
All that aside, the question remains whether it is possible,
without prejudice to the genius of Thomism, to institute a
reflective critique of knowledge that would imply neither
idealism or realism. Decidedly not, says Professor Gilson.
Like others but with the brilliance that has become his
hallmark, he has made it clear he wants no part of “critical
realism.” 16 The very words should stick in one’s throat; a
“criticalist” can never, never be a realist. Professor Gilson
is no doubt correct if the word “critique” is taken in the
Kantian sense, which in effect rules out realism from the
start. Others however, Maritain for one, do not believe that
“critical” philosophy should simply be defaulted to the
idealists—if the term be freed of every subjectivist (idealist)
presupposition.
But to get on with the more substantive matter of Pro­
fessor Gilson’s argument: Philosophical systems, he avers,
have an inner logic which controls their development. If we
begin with the doubt and the Cogito of Descartes, or with
the transcendentalism of Kant, we have barred all access to
reality and must necessarily land in idealism, with no hope
of escape. Or, if your initial step is knowledge in isolation
from reality, you will never find a way to reality. This does
not mean, however, that our only recourse against the
idealist position is to fall back on the native propensity of
man to be or act as a realist. Indeed not; for Thomistic
realism is a reasoned or reflective realism, one which I am
perfectly aware of the reasons for holding. It rests, not on
some obscure instinct, but on the evidence I have that my
knowledge relates to and depends on a real object. However,
16 See especially Gilson, E., Réalisme thomiste et critique de la
connaissance (Paris: Desclée de Brouwer, 1939).

Being: Criteriological Study
91
even with this initial datum in hand, there still remains,
from the standpoint of epistemology, a considerable task to
perform. For, while the fact of being related to an external
object is immediately evident, not so the manner and
means by which the relation comes about. In addition,
there must be a critical search into the various forms and
phases of knowledge to determine the exact role of each
and the relation of one form or phase to another. Through
this extensive labor of reflection and analysis the realism
which is natural develops into a realism which is truly
philosophic or methodic, yet so as not to entertain at any
time the supposition that my thinking may possibly be all
subjective. Thus Professor Gilson.
But which side to choose? Those who maintain that the
critical study of knowledge must from its inception give
assent to realism under pain of idealism? Or those of the
opinion that this assent (if it comes) can come later, whose
preference then is to begin with the bare fact of knowledge,
nothing said or assumed as to its transsubjective validity?
The answer, we believe, depends on what one makes of yet
another question, whether it is possible to conceive of
knowledge without implying its relation to reality.
To the purpose is a Thomist distinction of knowledge,
that of sensations and simple apprehensions on the one
hand, and judgments. The distinction is important as re­
gards the perception of truth, or the conformity of thought
with thing. Formally, or as known and recognized, truth
occurs only in judgment. In sensation proper and in simple
apprehensions the mind does not yet know if it has truth,
because it has not yet reflected on itself nor, in consequence,
adverted to its standing relative to the object it knows.

Ç2
Philosophy of St. Thomas: Metaphysics
This relation of thought or the thinking subject to the
external object is not revealed except in judgment. Accord­
ingly, it must be admitted that there is a moment in
knowledge when the object does not appear in clear dis­
tinction from the subject. We should hasten to add, how­
ever, that at this stage, when the formation of thought is
still in course and incomplete, knowledge itself has not yet
entered the focus of awareness; it is as though the subject
were wholly absorbed in the object, and not in itself. But
the moment I reflect, as is normal, on my act of knowledge
I become expressly conscious of my thought; in the same
breath subject and object are seen clearly distinct, and my
knowledge seen to be true.
The point to be made here is that the reflective work of
the mind together with the discoveries that accrue from it
presupposes that I have advanced from simple apprehen­
sion to judgment. Knowledge, then, may mean more than
simple apprehension; it may mean that an object has been
not merely presented (as in apprehension), but clearly
opposed to a subject and, still more, that there has been a
perception of the underlying relation of conformity between
them. In this larger sense there can be no knowledge with­
out judgment. And here, in judgment, occurs the critical
stage of knowledge, the point where the problem of the
real, or of the connection between thought and being
comes up. But is it not at the same time cleared up? To
isolate the judgment from its realist content seems impos­
sible. Such is the conclusion we shall be defending.
What we are saying is that in its reflection upon the
relation between subject and object of knowledge the mind
is naturally apprised of the realist character of its knowl-

Being: Criteriological Study
93
edge. To suggest, then, that in the reflective phase of the
act of knowledge the mind should still prescind from
realism, this would be a purely factitious state of affairs. The
natural mind does not have it so. The moment I reflect
upon my thought I am one that judges. So that to know,
for a human intelligence, is at the same time to judge; and
to judge, as we shall have occasion to repeat, is to appre­
hend that which is—really is. Consequently, if critical
philosophy (criteriology) is to start off with the fact of
knowledge, it has also to start off with realism. In the main,
then, Professor Gilson’s position seems the right one. But
much needs still to be said by way of clarifying the realism
we propose.
Enough has already been said, however, to give a more
complete answer to a question raised earlier: why and
where to conduct the “critique” of knowledge, within or
without the framework of metaphysics. Epistemologists
with a “criticalist” leaning, such as alluded to some para­
graphs back, were naturally led to separate the two
disciplines. Criteriology became a sort of introduction to
metaphysics, or at least an indispensable instrument of
verification designed to authenticate its findings. Not that
they denied all validity to a metaphysics based, as hereto­
fore, on realism without benefit of prior critique; but to be
thoroughly scientific we should begin, it was argued, by
putting man’s instruments of knowledge to the critical test,
admitting no preconceptions for or against.
Our answer is this. There may, or may not, be some
practical advantage—where (say) one’s purpose is pri­
marily apologetical—in assembling under one head those
various matters which have to do with the validation of

94
Philosophy of St. Thomas: Metaphysics
knowledge or the various kinds of knowledge. But no or
yes to that, we are absolutely convinced that to divorce the
criteriological enterprise from the metaphysical one is open
to grave objection; for it dissociates in an artificial and
precarious manner, two functions of the mind which are
intimately, in fact indivisibly conjoined in the fully devel­
oped act of knowledge, the judgment. Every judgment is by
nature reflective or, if one prefers, “critical.” And since
metaphysics builds especially on judgments, and this in the
authoritative manner that distinguishes it, to be reflective
and critical is of the essence of this science. Fully aware
of what he affirms, the metaphysician is also the one to
know why he affirms it, and that it is true. Whether in the
same instant the properly psychological appurtenances to
his knowledge are also clear—that is immaterial. What is to
the point for the metaphysician is what he finds as regards
the object itself. Now, what he finds there is absolutely
true; critique, preceding or concurrent, cannot change it
one particle. Metaphysics itself, indeed philosophy as such,
is reflective or critical; either that, or just a frolic of the
mind. Which comes to saying, as we have said before, that
for us there is but one sovereign wisdom of the natural
order, namely metaphysics, itself the critique pre-eminent.
3. Basic Reasons for the Attitude of Criticalists

and Idealists
Error, like infection, is never finally met and overcome
until we have probed its seat and traced the hidden proc­
esses. Tendencies as strong as those which, from antiquity,
have lured so many minds to skepticism, idealism, or
criticalism cannot be without all foundation. What, then,
lurks in these philosophies?

Being: Criteriological Study
95
Certainty of human knowledge rests ultimately on sense
perception. Both because of the nature of its object and
the complexity of the sensory apparatus, this perception is
attended by considerable obscurity, hence by no small
susceptibility to error. This, in part, explains the doubts
and misgivings which have led many to skepticism, all the
more that they lacked that larger view of the matter which
shows truth to be compossible with error. By an under­
standable reaction Plato and Descartes, among the more
eminent, thought the mind could be reassured by placing
the evidence for truth in an intelligible realm completely
removed from the world of sense. By this stroke the ob­
scurity that haunts the knowledge of this world of ours was
supposedly overcome, or at least circumvented; for the
clear and distinct idea which Descartes, for example, made
so much of was apparently won.
But all was not gain, to say the least. Sense knowledge
and intellectual knowledge, now sundered, stood as oppos­
ing realms, and bringing them together again would not be
easy. Various forms of parallelism were proposed, facile
solutions which shed little light on the integration of all the
factors of human knowledge. Mostly, however, philoso­
phers yielded to the temptation to ignore one side of
knowledge in favor of the other. Some, that is, as the
British Empiricists, tamely submitted to sensism; others,
perhaps more numerous, discarded the sensible to espouse
the pure idea, from which it was but a step to declare ideas
the only true existents. Excessive dissociation of sensory
knowledge from intellectual knowledge is, without a doubt,
the first and most pregnant source of idealist philosophies.
If the dissociation is carried to the point where the mind
becomes the determinative factor in the development of the

96
Philosophy of St. Thomas: Metaphysics
object, supplying instead of receiving its content, then the
stage is set for constructionist idealism, as witness Kant.
If on top of that comes the discernment—a correct one,
besides—that the most perfect thought is that which has
itself for its object, then a flight of the imagination, if bold
enough, can quite persuade an idealist mind that his is this
perfect thought, or at least a participation in it. Such is
idealism’s denouement; philosophy is confounded with
God’s own knowledge. Hegel, like Fichte and Schelling
before him, are there to prove it.
In this entire movement there is a kind of logic which
compels the successive developments. Underlying it all is,
as remarked, this divorce of mind and material nature, of
sensation and intellection against which Aristotle already
protested most vigorously. Human knowledge, he insisted
and must be joined in insisting, is in conformity with experi­
ence, is in consequence both sensory and intellective,
indissolubly so. No realism is solidly grounded if not on this
first fundamental.

III. CONCERNING THE AUTHENTIC
FOUNDATION OF REALISM

In the preceding pages we have framed, as we see it, the
starting point for a Thomist epistemology, and in framing
it have, in principle, already decided the question of
realism. For, as soon as by reflection one becomes aware of
all that is conveyed in the act of knowledge, it is no longer
possible to prescind from realism, as though its factuality
were still problematical. Such is the position we have taken.
We shall now examine it further with a view to clarifying
the grounds on which we have rested it. Before that, how-

Being: Criteriological Study
97
ever, we shall consider and pass upon certain attempts to
justify the realism of knowledge on a criticalist basis.

1. Regaining Reality via the Cogito
Descartes proposes two ways of doing this. Some neoThomists, not too surprisingly perhaps, have also enter­
tained them.
a) There is the way of The Meditations, where, toward
the end, Descartes seeks to re-establish contact with the
external world, from which he had cut himself off in the
beginning.17 Though (he argues) my clear and distinct
ideas concerning the material world might possibly originate
in myself, the same cannot be said of my sensations. These
involve passivity, and this demands a proportionate active
power from without. God, unless he be a deceiver, is not
this power, for he gives me no reason to think it him and
every reason to think it not. Consequently, the cause of
my sensations must be traced to corporeal realities. In
short, the external world must exist if there is to be a satis­
factory explanation for the existence of sensations.
The argument carries an air of plausibility, and many
adaptions of it have been formulated. But for all its plausi­
bility, as a demonstration of the realism of our knowledge
it will not do. To say that our sensations originate from an
exterior causality is, of course, correct; but we definitely do
not have to turn to this causality to become aware of the
objectivity of sensation. Besides, this manner of approach
gives a completely false twist to the mechanism of percep­
tion, for it implies that the sensory image is a purely
17 Meditations, VI; for bibliographical details, see note 3 of pres­
ent chapter.

g8
Philosophy of St. Thomas: Metaphysics
subjective double of external reality and the direct object
of perception, when as a matter of fact what is directly
perceived, through the image, is external reality. Also, this
recourse to the principle of causality is, from a criticalist
standpoint, questionable; the principle, namely, is used
before it has been justified. Evidently, this is not the way
to external reality.
b) In the Discourse on Method Descartes reassures us of
the realism of knowledge from another point of view, ap­
pealing to the certitude derived from perception of the self.
For this, of course, there was the precedent of none other
than St. Augustine. The existence of an external world (it
is argued) is certified through indubitable recognition of
the self, a recognition unique and immediate, a primary
datum of reflective consciousness. In this apperceptive ex­
perience there is, apparently, neither distance nor obstacle
between the subject that knows and the object that is
known. For, not only are they on the same ontological
plane; they are basically identical.
True enough; recognition of the self involves existence
of the self or the thinking subject. But the argument proves
little else, and even as far as it goes bears considerable
qualification. Thus, it should be noted that the grasp of the
self, however immediate and unimpeachable, is still a less
perfect form of knowledge than what is derived through the
medium of one’s essence, per essentiam, the characteristic
knowledge of pure spirits. Again, and most importantly,
what our intellect in its present condition of union with
the body grasps most immediately and directly, in short its
proper object, is not some spiritual reality but the things of
material nature. The basic experience, then, the one to

Being: Criteriological Study
99
which the mind awakens first, is that the perceived, or more
generally the things about me, simply are—whether they
are me or something else is a subsequent discovery. Conse­
quently, those who stand on apperception of the self stop
short of the actual source of knowledge, and furthermore,
invite the dissociation of sensible and intelligible which we
found seminal to the whole idealist movement. Finally,
from a more metaphysical standpoint, this caution: Do not
rest the absolute validity of knowledge on any particular
grasp of being but simply on the realist import of the
transcendental notion of being. This, as we have learned,
embraces implicitly all particular being and is not confined
to any one form of it.
2. The Elements of Judgment

We proceed now to a more positive consideration of the
nature of judgment. Our principal source will be the earliermentioned work of Roland-Gosselin,18 who, in the formative
part of his treatment, analyzes the act of knowledge with
exceptional accuracy.
Our inquiry, at the moment, comes to this: what is
knowledge, or what is it to know? We want the clearest
possible answer to this question. There is just one way to
get it, by examining with utmost attention the operations
which the mind performs in the course of any act of
knowledge. Not to protract the issue, we shall take it for
18 Namely Essai d’une étude critique de la connaissance; for pub­
lisher, etc. see note 11 of present chapter.
A more recent and equally notable study of judgment is Hoenen,
Peter H. J., Reality and Judgment According to St. Thomas; trans,
from the French by Henry F. Tiblier (Chicago: Henry Regnery Co.,
1952. Library of Living Catholic Thought).

loo
Philosophy of St. Thomas: Metaphysics
granted that the perfective moment of knowledge, the one
in which, in particular, the mind becomes distinctly aware
of its knowledge is the judgment. From here on, accord­
ingly, our inquiry into the nature of knowledge will be
mostly an inquiry into the nature of judgment.
Any instance of judgment will do for analysis. Suppose,
then, we say “this curtain is blue.” What are the constitu­
tive elements of this judgment? Perhaps the first thing to
notice is that there has been some connection or association
established. I had before my mind the two notions “this
curtain” and the color “blue.” In saying “this curtain is
blue” I made a mental composition of the two notions;
which is to say, I attributed “blue” to “curtain.” A judg­
ment, then, embodies a relation of attribution or predica­
tion, one thing said of another.
There is, however, yet another and in a sense a more
basic relation involved. In making the judgment that the
curtain is blue I also tell myself, mentally at least, that what
I am saying (the attribution) is true. What is meant by “is
true”? Simply that the attribution made in the judgment
is in agreement with reality. I find my judgment true be­
cause I see that between what it says and what is, between
my mind and reality, there exists a relation of agreement or
conformity—adaequatio rei et intellectus, as the Scholastic
idiom has it. Thus, in a judgment such as here analyzed
there is a twofold relation expressed, one between subject
and predicate, another (no less discerned) between my
thought and something that is, which latter phrase is in a
way the definition of being. The second relation, that of
agreement between mind and reality, constitutes the truth
of the judgment and is an essential element of it. That it is

Being: Criteriological Study
101
essential is readily shown. For, suppose that I cancel the
agreement by denying it, as in “no, this curtain is not really
blue.” In that case my first judgment is at once discredited
as not in conformity with reality, or with what the curtain
really is; and the relation that had been established between
subject (curtain) and predicate (blue) is destroyed.
It would not be difficult to apply the foregoing analysis to
any sort of judgment, though of course categorical judg­
ments, in which the copula “is” is explicitly stated, lend
themselves most readily to the purpose. But even where the
copula is only implied, as in “the sun shines,” the point at
issue is evident enough. Here, as always, what my mind
thinks is not true unless what it thinks refers to (in the
sense of agrees with) reality, with what is. As for other
judgments distinguished by logicians, whatever their form
the same principle rules; affirmation or denial relates to
reality. We may, then, conclude with Roland-Gosselin that
“the analysis of judgment warrants the assertion that the
object is not entirely determined by the subject, nor can it
(the object) be affirmed by the subject unless it is thought
in relation to what is. Failing this relation, a judgment is
worthless.” 19
A further word should now be said on an aspect of the
judicative process to which some reference has already been
made, namely, the reason why the mind affirms (or denies)
one thing of another. Why, as in our earlier example, do I
say “this curtain is blue”? What moves me to the affirma­
tion? The answer is all important. I pronounce the curtain
blue because I see it is blue; I see it clearly. Not only, in
other words, do I judge the curtain blue, but I judge that I
19 Op. cit. (note 18), p. 45. Translation mine.—[Tr.]

102
Philosophy of St. Thomas: Metaphysics
see it so, that the thing is manifest to me. In judgment,
accordingly, the mind is governed by some manifestation
on the part of the object, but the manifestation or evi­
dence need not be a matter of sense perception. Indeed not;
for in judgments of the most abstract kind I also see that
what I am saying is true, but I see it intellectually. Thus in
“the whole is greater than the part” the manifestation of
the truth is intellectual. The eye can see (say) a whole
apple, or part of one, but the mind sees that universally
the whole is greater than the part. Evidence—the clear
visibility of something—is a constitutive element of every
judgment.
Kantian philosophers would reduce the formation of
judgment to an act of pure synthesis, as though it was in
no way determined by the external object but originated
solely from the constitutional habit of the mind. This, it
will be remembered, harks back to the idealist thesis that
the mind is pure activity. We can only repeat that the
realist, without going to the idealist extreme, also acknowl­
edges the active role of the mind in judgment as in other
operations. The mind does indeed by its own activity at­
tribute the predicate to the subject; however, the attribu­
tion is not made blindly but only because the mind sees
itself determined to it by the object. The pure synthesis of
Kant, on the other hand, is to all intents and purposes a
judgment without insight, a blind judgment. Yet the reali­
ties of human psychology do not support Kant; there just
is no way for the mind to lay hold of what it does not in
some way see.
In sum, a judgment, as analysis shows, is constituted by
a twofold relation; for it rests ultimately on the validity of
the mind’s grasp of being, as well as on evidence of judg-

Being: Criteriological Study
103
ment’s relation to being. “Every judgment,” to call again
on Roland-Gosselin, “presupposes that the activity of the
subject [the mind] originates, at least in its logical aspect,
with an evidence of being, and requires for its complete
determination an evidence that the attribution, through
which judgment is expressed, has relation to ‘what is.’ ” 20
3. The Realist Import of Judgment

Judgment, we have been saying, hinges on being. What
is this being that controls the judgment and which, in turn,
judgment expresses? Ruled out, in the light of earlier re­
marks, are idealist acceptations of it. So, the being to which
judgment refers is not the more or less subjective being
denoted by the copula. In “the curtain is blue” the reality
which the mind has in view and by which it is measured
does not lie in the “is” of the proposition. The being of the
proposition as such is indeed posited by the mind; so much
we may grant the idealist. But this is no more than the ens
verum, the “being true” which both Aristotle and St.
Thomas carefully distinguish from ens simpliciter, being in
the absolute or objective sense. Ens verum (“the being of
truth” as opposed to “the truth of being”) refers only to
the fact of conformity between the intellect and objective
being. The latter (objective being) is precisely the being of
which judgment is a function, so that the being which con­
sists of the truth-relation (the aforesaid conformity) has no
meaning except as it relates to objective being. It is utterly
incorrect, then, to say in the idealist fashion that by my
affirmation of being I myself have posited being, as though
it were a form or determination emanating from my mind.
Nor must the being which measures my thought be re20 Op. cit. p. 51. Translation mine.—[Tr.]

lOj.
Philosophy of St. Thomas: Metaphysics
garded as a pure object whose whole and sole reality con­
sisted in being thought by the mind. The object-relation—
that a thing stands in the relation of object to a subject
—this, it should be plain, is not what constitutes the thing
in the first place, any more than being as known can stand
without the being of which it is but a particular mode. The
signification of being transcends the signification of object;
which is to say that being as such is prior to object as such.
In the most formal sense, therefore, being is not what is
known, or what is an object of knowledge.21
The being of which we now speak is the being which in
an earlier context we defined as “that which is,” a composite
in which we distinguished the aspect “something” (the
essence') and the aspect “which is” (its existence, or its
ordering to existence). The latter aspect, moreover, was
identified as the ultimate determinant or actuality of being.
What we said of being is to be said of the real. The real is
precisely that which exists or which stands in (actual or
possible) relation to existence. Hence, it is all the same
whether we say that knowledge relates to what is, or refers
to the real, or has realist value. This seems simple enough; it
21 It would, of course, be a gross misreading of the author to go
from “being is not what is known” to tire completely erroneous
conversion “what is known is not being.” The qualifying words in
the most formal sense are therefore all-important. To say that being
in the formal sense is not what is known is simply to say that “to be
known” is not the definition of being; else, things would not exist
unless or except when they are known, and to know them w’ould be
equivalent to causing or creating them—a state of affairs which,
with some elucidations, is true of the divine mind alone. Hence the
author’s charge in the fore part of the chapter that absolute idealists,
who claim the mind creates its object, arrogate to themselves the
mode of knowledge prerogative of the Deity.—[Tr.]

Being: Cñteriological Study
105
is also decisive. To have understood it is to have found, as by
a single stroke, the key to the riddle of realism in knowl­
edge. Because in judging I take my measure from what is,
my knowledge has by nature a realist import. So, once for
all, to know (sc. as in judgment) is to perceive what is.
Before leaving this discussion one further point concern­
ing the real should be made. The real to which judgments
refer and which they affirm is not all of the same generality
but differs with the modes and the orders of knowledge. If
I say “man is a biped,” I make a universal affirmation of
whose objective validity there can be no doubt, but the
object affirmed (a universal nature) does not exist in the
manner of this (individual) table on which I write and
whose existence I also affirm. Likewise, “the end of the
world” is thought of as something, though its realization lies
in the future. In these and like instances my judgment does
indeed refer to existent being as such, but according to
modes of realization which are not all alike. Thought, in its
realism, respects and reflects the mode of reality proper to
each different object of thought. In sum, knowledge takes
many forms, and its realism varies accordingly. To appraise
the realism of its different forms, however, presupposes a
more detailed study than is here feasible.
Conclusion. Though of necessity far from exhaustive, the
foregoing analysis will have been adequate if, as we trust, it
has demonstrated the foundation on which the realism of
knowledge must stand. Some—improperly, we believe—
have tried to find this foundation in the circumstances of
sensation (which presumably needs an external cause), or
in the perception of self (which includes the body, an ex­
ternal reality for the mind), or in the self-recognition of the

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Philosophy of St. Thomas: Metaphysics
spiritual subject (I think, therefore I am)—ways, all of
these, more or less futile. The basic assurance of realism lies
in none of them but solely in being, and this as discovered
to the mind by its reflection in judgment. This is the sum
and substance of what we have set forth.
A fuller treatment of the foundation of realism would
take account of more concrete considerations as well, such
as the demands of practical reason, the convictions of man­
kind, the assumptions on which men conduct human affairs,
etc. Doubtless, there is something to be said for arguments
woven around these elements of human experience, since
practical life does indeed presuppose and point to the truth
of realism. But they could never be a substitute for the direct
evidence supplied in judgment, where, by reflection, the
mind is granted an immediate awareness of the realism of
its speculative knowledge. This is the knowledge (rather
than that of the practical order) through which the funda­
mental conformity of thought with being is most verily
apprehended. Thus, whether in metaphysics proper or in
the theory of knowledge, the starting point is not in the
order of action but in the reflective grasp of being, a grasp
that occurs in judgment.
IV. FIRST PRINCIPLES

a) To the study of being as being Aristotle joins the study
of certain primary truths which he names ‘axioms.’ 22 The
reason is clearly stated; these truths, he says, should be
studied in the science of being because they have the same
amplitude or universality as being. “Since,” in his own
words, “it is evident that the axioms hold good for all beings
22 Cf. Metaph. r, j.

Being: Criteriological Study
107
as beings ... he who studies being as being should also
take account of them.” 23
In line with this recommendation of Aristotle’s, many
metaphysical authors in his tradition take up first principles
immediately after their treatment of being as such. Others,
it is true, consign this topic to logic, pleading that these
principles are the basic laws which govern every exercise
of reason. That they do so govern is unquestionable; yet
prior to their directive function over the mind is their
operation as objective laws of being, and it is in the latter
capacity that they are first as well as immediately made
known to us. Hence, to couple the consideration of these
primary truths with the study of being as being is, as
Aristotle plainly shows, the proper course of inquiry. The
consideration, moreover, which is calculated to assure the
mind of all first truths, falls naturally within the scheme of
the present chapter, that is, within the context of the
critical study of being and of the first foundations of our
knowledge. Yes, in the matter of first principles metaphysics
and critique (criteriology) are practically equivalent.
b) To start off, we should be clear as to the meaning of
first principle. Generally speaking first principles, as the
name implies, are something primary or ultimate. Working
backward (Scholastically: “in the ascending order”), they
represent the final or ultimate link in the chain of knowl­
edge, the last limit beyond which the resolution of knowl­
edge cannot go. As a rule the expression “first principles”
refers to judgments or propositions, but St. Thomas also
applies it to the terms or concepts, the elements as it were,
of a proposition. We shall restrict our inquiry to the first
23 Loc. cit. 1005 a 27-29.

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Philosophy of St. Thomas: Metaphysics
meaning, to principles in the form of propositions. Also, it
should be obvious that in the study of being and its first
principles we have not to concern ourselves with principles
that are special to any science but only with those that
pertain to all being and so are absolutely common—com­
mon to each and every science.
Considered in themselves first principles must be not only
true and necessary, as a matter of course, but also immediate
(Scholastically: per se nota). Immediacy, as applied to a
principle, means that the truth of it is understood without
the help of intermediate notions or middle terms. We have
only to grasp the meaning of the terms that make up the
principle, and the truth of the proposition becomes in­
stantly evident. In this sense first principles are said to be
self-evident or known through themselves, the literal render­
ing of per se nota. When, moreover, a principle is abso­
lutely first, the terms it comprises must also be absolutely
first or simple, hence incapable of reduction to prior no­
tions. If they could be reduced, they would not be first.
Every science has its principles, which may not be abso­
lutely first. Even then, however, the principles, as the name
indicates, are basic points of reference for the science; the
science rests on them and every development necessarily
implies and presupposes them. As for the metaphysical
principles relating to being, these are first to all others, so
that all knowledge of whatever order is subordinate to
them. Hence the capital importance of these first or primary
truths.
c) Which among the metaphysical principles just re­
ferred to comes before all others? Thomists today do not
agree. For Aristotle, on the other hand, the question was

Being: Criteriological Study
log
settled.24 This principle, he argued, would have to meet
three conditions; it must be i)the best known, z)the first
known, and ?)the most certain, “about which it is impos­
sible to be mistaken.” Which is this principle? For Aristotle
it is unequivocally the principle of noncontradiction—or,
elliptically, “of contradiction.” 25
i. The Principle of Noncontradiction
a) The formulation of the principle varies. Aristotle
proposes, without preliminaries, the following: “it is im­
possible that the same attribute belong and at the same
time not belong to the same subject in the same respect.”
St. Thomas’ rendition of this is:

impossibile est eidem simul inesse et non inesse idem
secundum idem,
which in English comes to: “it is impossible to affirm and
to deny the same thing at the same time in the same
respect.”
So formulated, the immediate reference of the principle
of noncontradiction is to operations of the mind, to attribu­
tion and nonattribution (i.e. affirmation and negation),
which are declared mutually exclusive under the conditions
of the principle. A more metaphysically-oriented formula­
tion can be made, seeing that in any judgment—we are
dealing with principles that are judgments—the mind is
determined by the reality which serves as its object. For
example, I judge that the sky is blue because I see that it is
actually blue. Consequently, it is more conformable even
24 Cf. Metaph. r, j, 1005 b 5 ff.
25 Cf. Text IV, “Concerning the First Principle of Demonstra­
tion,” p. 252.

no
Philosophy of St. Thomas: Metaphysics
to the structure of knowledge to word the principle with a
view to its objective content, in which case it will read
"being is not nonbeing,” or, same sense, “what is, is not
what is not.” So, to follow our usual practice, we have in
Latin:

ens non est non ens.
In metaphysics, evidently, where our standpoint is that of
objective being, the preferred formulation should be the
objective one, “being is not nonbeing” or its aforemen­
tioned variant.
b) Next, we examine the steps by which the mind be­
comes cognizant of the principle. Plainly, the principle
results from comparing and contrasting two notions, “be­
ing” and “nonbeing.” The being here in question is none
other than that first datum of the intellect of which we
spoke in the preceding chapter. As for the notion of nonbeing, the mind sees at once that its positive content is
again the notion of being, from which it but differs by the
negation it bears, solely an act of the mind. This response
of the mind to the conception of being, the negation of it,
is absolutely primary, a comportment so basic and instinc­
tive to the mind that there is no way of defining it except
through itself. The mind, accordingly, first apprehends
(and conceives) being; then it denies (or conceives the
negation of) being; and thus it has the notion, or the
pseudo-notion, of nonbeing.
Comparing the notions of being and nonbeing, we see
and cannot fail to see that they are irreducible to each
other. The recognition of their incompatibility is imme­
diate and necessary, a primordial datum of the mind.

Being: Criteriological Study
m
Being, as being, can never be nonbeing. In consequence of
this opposition, which is absolute and irresoluble, it is im­
possible—and this was our first formulation of the principle
—to both affirm and deny the same thing at the same time
and in the same respect. Such simultaneous affirmation and
denial would in effect identify being with nonbeing, and
this the mind is utterly incapable of doing—the mind, I say,
because the speech of man can say even what the mind
cannot. All told, then, in the discovery of the principle of
noncontradiction the mind employs but one positive notion,
that of being, upon the conception of which it posits two
successive acts of negation, negation of being and of com­
patibility between being and nonbeing. This done, it only
remains to give verbal expression to the objective incom­
patibility thus discovered.
c) Having seen how the mind arrives at the principle of
noncontradiction, we come to the question of its validity,
or the grounds for asserting its validity. That the principle
is an absolute, objective truth is immediately or self-evident;
as soon as the mind grasps the notion of being and nonbeing it necessarily recognizes their mutual exclusivity as
well as the absolute character of the exclusion; and this, in
essence, is the principle. But is there another way, or rather
a way—since what is self-evident is not proved—to justify
and certify the principle? A direct demonstration is obvi­
ously out of the question, for this would needs be based on
the apprehension of a prior truth, the impossibility of which
is clear from the fact that nothing is prior to being. But
what of an indirect demonstration, the refutation by ab­
surdity? In general, refutation by absurdity consists in
showing that a certain proposition necessarily involves the

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holder in contradiction; he is saying what he is not saying,
or not saying what he is saying. In the present instance such
a maneuver would be beside the point, since the possibility
of contradiction—the possibility of contradicting the prin­
ciple—is precisely what its adversary maintains. (Note again
that what is at stake is not the possibility of mouthing a
contradiction but the possibility of thinking it, or thinking
it true.)
In our case, then, the adversary, if he is to be met on his
own grounds, is not trapped by confronting him with his
contradiction of himself but by reducing him to silence. To
affirm the identity of contradictories, in other words, is no
longer to have a distinct object of thought; it is to have no
thought at all. Thus, if the adversary concedes that he has
some definite thing in mind and thereby attaches some
meaning to the word that expresses his thought, he auto­
matically acknowledges that being is not contradictory; he
either has an object of thought or not, either means some­
thing or does not. If, in spite of this, he sticks to his oral
denial of the principle, the denial is a mere trick of words,
deprived of anything distinguishable as an object of thought.
The alternatives here are to think of something or not to
think at all; there is no other possibility. In sum, if you wish
to think you must fix on some determined object; you must,
that is, acknowledge the dictates of being.
d) A final word pertains to the extent of the principle’s
applicability. Since it originates from the notion of being,
the principle, taken in itself and unrestrictedly, holds good
for all modes of being, which is simply to say for all being;
and, correlatively, it holds good for all thought relating to
being, which is again to say for all thought, as this always

Being: Criteriological Study
113
relates to being of some kind. However, the beings of our
experience, because they are many and variable, are none of
them endowed with the fullness of being. While in some
respects they are indeed being, in other respects they are
nonbeing—there is being which is not their being. Conse­
quently, the principle of noncontradiction applies to such
beings but from certain points of view and within certain
limits; what it says in effect is that so far as they are being,
they are not nonbeing. Only for absolute being, which is
God, does the principle hold in absolute manner.
2. The Principle of Identity

Modern philosophers, Scholastics included, speak of yet
another, an affirmative principle which is thought to go
with the principle of noncontradiction and by some is even
placed ahead of it. This is the principle of identity, by
which being is predicated of itself.
a) St. Thomas, for his part, makes no mention of this
principle, at least not in so many words. When, in logic or
in metaphysics, he treats of the axioms, the primary truths,
nothing is ever said about this one. Nevertheless, something
akin to the principle, or even its equivalent, can be traced
in his thought. For one thing, St. Thomas does speak of
identity and tells us very exactly what he means by it,
namely, the mode of unity proper to substance. Hence, to
affirm the identity of being would, in a way, be the same as
to assert its unity. Thus understood, the principle of iden­
tity would but come to another expression for what might
be called the principle of unity of being: that every being is
one, or identical with itself. Of this, of course, there can be
no doubt. That every being is one or identical with itself is

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Philosophy of St. Thomas: Metaphysics
a very true proposition, and a very accurate one at that—
known, moreover, with all the immediacy of a first prin­
ciple. However, in introducing the notion of the transcen­
dental one, the proposition goes beyond the mere notion of
being, and this, it is agreed, the principle of identity must
not do. Consequently, if the principle is to have a formal
basis in St. Thomas, recourse must be had to some other
doctrinal context, which, we believe, is provided in the
following passage:

One cannot find anything that is predicated affirmatively and
absolutely of every being except its essence, according to which
it is said to be, and is given the name “thing” (res). For, as
Avicenna explains [Metaph.1,6], “thing” differs from “being”
(ens) in this, that being is named after the act of existing [ab
actu essendi], whereas thing expresses the quiddity or essence
of the being.26

In the distinction made in this text we find the clue to the
principle of identity, such as accords with the thought of
St. Thomas.
b) It is at once clear that unless the predicate differs
somehow from the subject, there can be no judgment in the
true sense of the word. A strictly tautological predication of
being (where “being” is used twice with the identical mean­
ing) constitutes no judgment at all. Thus, “being is being”
tells us nothing unless the second “being” enlarges, how­
ever modestly, upon the first. And here enters a problem.
Being, it is obvious, must be the subject of any statement of
the principle of identity; yet being signifies everything.
Where, then, find a predicate that will add anything to the
26 De Verit. q. i, a. i c.

Being: Criteriological Study
115
signification of the subject? St. Thomas, as we have said,
points the way in the above citation, making within being
itself the distinction, now familiar, of being as existent and
being as essence. The principle, accordingly, comes to “be­
ing (as existent) is being (as essence).”
Authors are agreed that this is the general sense of the
principle, even though in their explication of it some differ­
ences appear. If the principle is thought to accentuate the
distinction between essence or thing (res) and the act of
existing, then the reading of it might well be, as GarrigouLagrange proposes, “every being is something determinate,
something of a determinate nature which constitutes it in
its proper self.” 27 In short, every being has a certain nature.
On the other hand, it would seem preferable to keep the
formulation of the principle more strictly within the limits
of the notion “what exists” (ens), namely, by considering
essence not as a certain essence but as the essence of being
itself. Thus, instead of, Is being something determinate?
the question would be, What thing, what nature is being?
and the reply (the principle), It is being. In other words,
“every being is what it is,” as Maritain phrases it;28 or
simply, “being is being”—ens est ens—, which says in effect
27 Garrigou-Legrange, R., O.P., Le sens commun, jme éd. (Paris:
Bcauchesne, 1922), p. 166; which, in the original reads: “Tout être
est quelque chose de déterminé, d’une nature déterminée qui le
constitue en propre.”
See also (idem), God: His Existence and His Nature, I, 159-163;
for publisher, etc. see note 15, chapter 2, p. 49.
28 Cf. Maritain, Jacques, A Preface to Metaphysics, pp. 92-93
(New York: Sheed & Ward, 1941). Available in paperback, Mentor
Omega Book (New York: The New American Library of World
Literature, Inc., 1962).

116
Philosophy of St. Thomas: Metaphysics
“being has for nature to be.” These latter formulas win our
acceptance, for the reason that they keep closer to the
mind’s original discovery of being—closer than formula­
tions which, like that of Père Garrigou-Lagrange, single out
the determination being receives from essence (res).
c) Concerning some other aspects of the principle, we
have only to repeat what was said apropos of the principle
of noncontradiction. In both, the mind, affirming or deny­
ing, expresses itself as it does only because it sees the
objective agreement or nonagreement, as the case may be,
between the two terms involved, between subject and
predicate. Furthermore, like the principle of noncontradic­
tion, that of identity is coextensive with being; it holds for
all being. Again, however, it holds proportionately: for
limited or imperfect beings, only so far as they are (in some
respects, it will be recalled, they are not). To God, on the
other hand, and only to him it applies simply; for, as he
alone is being absolutely, so he alone is being identically.
d) There remains one question. To which principle
should the primacy go, to identity or noncontradiction?
Objectively speaking, or from the view of notional content,
both presuppose but one (and that the same) datum, namely
being; and both terminate in the same object, again being.
Each of them, moreover, is immediate or self-evident; nor
is the truth of one subordinate to the truth of the other.
On the subjective side (the side of mental activity), a differ­
ence is more easily found: two acts of negation in the one
(noncontradiction); discrimination of essence and existence
and an act of affirmation in the other (identity). From this
point of view it is perhaps possible to speak of (psycho­
logical or logical) priority. In metaphysics, however, since

Being: Criteriological Study
ny
neither principle goes beyond the explicit content of the
notion of being, the question of priority has not to be
raised.
3. Other Principles

Together with the principle of noncontradiction Aristotle
discusses an immediate consequence of it, “that between
the affirmation and negation of being no middle ground is
possible; that being is or is not.” This is commonly known
as the law of excluded middle, and the mention of it shall
suffice. Modern authors include for discussion at this point
a number of other principles: principle of sufficient reason,
of causality, of finality, of substance. These principles are
certainly essential to the mind in its manifold work of
inquiry; but, considering that they deal with notions and
distinctions which, in regular procedure, have not been met
with at this stage of metaphysical study, it is more logical
to speak of them later. We shall keep to this more method­
ical course and in the next chapter go at once to the prop­
erties of being, that is, the properties other than being itself
considered as “quiddity” and in its opposition to nonbeing.

Concluding note: On the origin and formation of first
principles. These principles are not innate; they are not
known prior to all experience. What is innate is the power
to know them, the intellect, which at first has no actual
knowledge whatever, though it is in potency, pure potency,
to every intelligible. Knowledge of first principles, specifi­
cally of the ones studied above, is acquired in the same way
as other knowledge, through the senses. From the presenta­
tions of sense the intellect abstracts the notion of being;

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Philosophy of St. Thomas: Metaphysics
once this notion is formed the principles are formed, imme­
diately. Our first recognition of them, however, comes from
particular cases, from this or that being; not until being is
grasped in its universality are the principles formulated in
their universality.
While not innate, first principles are nevertheless said to
be natural to our intellect, in the sense that they are a
necessary, never-failing consequent of its operation; thus, if
the intellect acts at all, it cannot but be in possession of
them. In the human intellect, moreover, they serve as a
kind of habit (habitus'), a stable disposition which enables a
faculty to function more readily and more dependably.
This habit, furthermore, is twofold, according as the prin­
ciples pertain to the speculative order or to practical action.
In metaphysics, keep in mind, we are concerned with first
principles of the speculative order; not innate, they never­
theless perfect the intellect naturally rather than by de­
liberate cultivation.29
29 Cf. In IV Metaph. lect. 6, no. 599.

t CHAPTER 4

The Transcendental

I. THE TRANSCENDENTALS IN GENERAL

t IN the chapter on being1 we saw that the meta­
physical notion of being, which is an analogous concept,
embraces all reality in a proportional unity. We found,
moreover, that the notion is a complex one, adverting in
particular to the distinct aspects of essence and existence.
We have now to consider some other aspects of being, its
properties (as they are called), for the study of being as
being should include whatever is inseparable from and con­
vertible with being. This, of course, should logically be done
before treating of the categories, particular modes of being.
Parenthetically, this further determination of being—
finding its properties, the aspects or elements common to
being as being—is not to be done in the manner of some
idealists, by a dialectic of pure deduction; for from the mere
notion of being we get—the mere notion of being. The
properties of being are based in reality and must be sought
there; indeed they are given, at least in principle, when
being is given, in the mind’s first apprehension. The ques1 Namely chapter 2.

120
Philosophy of St. Thomas: Metaphysics
tion, then, is not one of drawing something from an abstrac­
tion, that is, from the abstract notion of being but rather
from the reality of being, the same being which the mind
first experiences. By redirecting its attention to the content
of this experience the mind becomes explicitly aware of the
properties of being and thus acquires a more integral con­
ception of the reality which constitutes its initial datum.
Granted the necessity of recourse to experience for prog­
ress in metaphysical thought, we have still to determine how
“anything” can be added to being. St. Thomas, in a classic
passage, explains the point perfectly.2 Being, he says, can­
not be diversified in the manner of a genus, by differences
that would not be contained in being itself—a specific
difference is not actually contained in a genus.3 Being can
only be differentiated through modes which are intrinsic to
being itself. Basically, there are but two ways for this differ­
entiation to occur. Either the modes in question are par­
ticular modes, constituting the so-called predicaments of
being; or they are modes which pertain to being universally
and necessarily, to every being without exception. In St.
Thomas’ words,

nothing can be added to being as though it were something not
included in being—in the way that a difference is added to a
genus or an accident to a subject—for every reality is essentially
a being. Tire Philosopher has shown this by proving that being
cannot be a genus [Metaph.B,$, 993 b 23]. Yet, in this sense
some predicates may be said to add to being, namely, inasmuch
as they express a mode of being not expressed by the term
being. This happens in two ways. First, the mode expressed is
2 Cf. De Verit. q. 1, a. 1 c.
3 Reference to this point was made earlier. Cf. chapter 2, p. 45 f.

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121
some particular manner of being; for there are different grades
of being, according to which we speak of different modes of
existence; and conformably to these modes the different genera
of things are drawn up. . . . Second, something is said to add
to being because the mode it expresses is one that is common
and consequent upon every being. . . ,4

These modes, “consequent upon every being,” constitute,
in the accepted parlance, the transcendental properties of
being; of which severally in the course of the chapter. For
the present, note that they are not “properties” in the strict
sense, for then they would express something that is ex­
trinsic to the nature of being, a manifest impossibility.
They are therefore properties in a larger sense, as insepa­
rable from being and designating it under another aspect.
As for “transcendental,” this they are in the same sense as
being: that which occurs in all being, and so transcends any
particular category of it. And because they are as universal
as being itself, the transcendental modes are spoken of as
convertible -with being, so that in a proposition where being
is the subject and one of the common modes the predicate
(or vice versa), we may interchange them. If, for example,
“being is one,” then “the one is being,” with no shift of
meaning.
1. Derivation of the Transcendentals

As found in manuals of philosophy, the theory of trans­
cendentals—being, one, true, good—seems a rather simple,
quickly-ordered affair; such, in its finished form, it may well
be. Historically, however, the course of development was
4 De Verit. q. 1, a. 1; trans, by Robert W. Mulligan, S.J., Truth,
Vol. I (Chicago: Henry Regnery Company, 1952).

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not quick and easy. Progress came gradually, with ensuing
complexity; and when the doctrine had achieved maturity,
it was the work not of one but of many, successive
contributors.
Aristotle states very clearly what is required for a notion
to be transcendental, at least so far as it applies to the one,
whose thorough identity and convertibility with being he
noted to perfection.5 By contrast, Aristotle does not treat
of the good in the same metaphysical way, under the aspect
of a universal property, so as to show its identity with being.
For him the good, to be sure, is everywhere the principle of
action, but its assimilation to the order of being never quite
materializes. Much the same goes for the true, and for
being as true; these are dealt with only in their subjective
side, as pertaining to the terminal or perfective phase of
the act of knowledge. In this sense the true, as we saw in
the preceding chapter, is a property of judgment rather
than of being; which explains why the true does not enter
Aristotle’s philosophy of being, or enters it only to be
dismissed.
Actually, the formation of what was to become the
standard triad of transcendentals relative to being—the one,
the true, the good—was the work of Christian philosophy, in
which, moreover, the first conceptions of the triad were
mostly theologically inspired. One, true, and good were
thought of as attributes of the primary Being, and were
referred to each of the three Persons of the Trinity. But in
creatures, too, signs or vestiges of these divine attributes
were sought. From the beginning of the thirteenth century
any number of Summas appeared, as well as Commentaries
6 Cf. Metaph. r, 2.

The Transcendentals
123
on the Sentences of Peter Lombard, which testify to this
first and largely theological development of the doctrine of
transcendentals. Its philosophical elaboration, on the other
hand, appears to have been the special contribution of St.
Thomas, from whom the doctrine does indeed emerge in
definitive form. We have already made reference to his
article that is basic to the subject;6 we proceed now to
examine it more closely.
Since being is what the intellect first conceives of any­
thing, all other conceptions must be formed by some addi­
tion to this fundamental notion. We have seen, however,
that addition to being cannot be made as though to a genus,
but rather by expressing various modes not explicitly signi­
fied in the mere notion of being. If the modes are particular,
they represent predicaments; if universal, they express trans­
cendental being and hence are named “transcendentals.”
But on what basis are the universal modes themselves
distinguished? First, according as they pertain to being
taken absolutely (in itself), or relatively (to another being).
In the first case, that of being in itself, the mode expresses
something of being either affirmatively or negatively, and
these alternatives give rise to two of the transcendental
notions. Affirmatively, the only possible attribution to every
being is that of its essence, to which corresponds the term
“thing” (res). Negatively, there is also a single predication
of being, its undividedness, signified in the term “one”
(unum). “Thing” and “one,” accordingly, are the two
transcendentals which pertain to being absolutely.
On the other hand, being may also be considered rela­
tively, or under the relation of one being to another, which
8 Namely De Verit. q. 1. a. 1.

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may be a relation of distinction or one of conformity.
Being, conceived of as distinct from others, is named
aliquid, “something,” as though to say “some other thing.”
It is easy to see that every being is distinct from every other
being, but how can every being be conformed or assimilated
to some other being? This is possible only if there is a being
to which every other being is somehow accommodated.
Such is the human soul, which by its powers of knowledge
and appetition enjoys this amplitude. The accommodation
or correspondence of being to the powers of knowledge is
expressed by the term “true” (verum); whereas the accom­
modation to the powers of appetition is expressed by the
“good” (bonum). In short, then, three things may be said
of every being taken relatively: true, good, and otherness
(some other thing). With that, all the transcendentals are
accounted for. On this capital point, however, we ought to
hear St. Thomas again, this time in full:
This mode [common and consequent upon every being] can be
taken in two ways: first, as following upon every being consid­
ered absolutely; second, as following upon every being consid­
ered in relation to another. In the first, the term is used in two
ways, because it expresses something in the being either affirma­
tively or negatively. However, one cannot find anything that is
predicated affirmatively and absolutely of every being except
its essence, according to which it is said to be, and is given the
name “thing” (res). For, as Avicenna explains [Metaph.1,6],
“thing” differs from “being” (ens) in this, that being is named
after the act of existing [ab actu essendi], whereas thing ex­
presses the quiddity or the essence of the being. As for the
negation consequent upon every being considered absolutely,
this is its undividedness, which is expressed by one; for the one
is simply undivided being.

The Transcendentals
125
If the mode of being is taken in the second way—according
to the relation of one being to another—we find a twofold use.
The first is based on the distinction of one being from another,
and this distinctness is expressed by the word something
{aliquid), which implies, as it were, some other thing. For, just
as being is said to be one in so far as it is without division in
itself, so it is said to be something in so far as it is divided from
others. The second division is based on the correspondence one
being has with another. This is possible only if there is some­
thing which is such that it agrees with every being. Such a
being is the soul, which “in some way is all things,” as is said
in the treatise On the Soul [III,8, 431 b 21]. The soul, however,
has both knowing and appetitive powers. Good expresses the
correspondence of being to the appetitive power. . . . True
expresses the correspondence of being to the knowing power... ,7

As readily seen, St. Thomas in this passage lists, besides
being itself, five transcendental notions: thing, one, some­
thing, true, good—res, unum, aliquid, verum, bonum. The
term “thing,” however, does not, it seems, say anything that
is not explicitly said by the notion of being, for it does no
more than express the aspect of essence in things; some
authors, as a matter of fact, do not consider it a transcen­
dental property in the truest sense. As for “something,” it
can be interpreted two ways. Either it denotes the opposi­
tion or distinction of one being to another, and then it may
be regarded as a consequence of the unity of being; or it
marks the opposition of being to nonbeing—namely, that
being is something other than nonbeing—, in which case it
expresses an original and primary aspect of being. Yet
granted the authenticity of “thing” and “something” as
transcendental properties of being, it is doubtful that they
7 De 'Verit. q. 1. a. 1 c; for translation, etc. see note 4.

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command the same philosophical interest as does the triad
of the one, the true, the good, deservedly recognized as the
classical three. To them, modern authors like to add the
“beautiful” (pulchrum), which does indeed appear to be an
aspect of all being. But though it denotes the agreement of
being with the soul, it does so through the conjoint powers
of knowledge and appetition; hence, instead of a primary
transcendental it is more properly deemed a derivative one.

2. Nature of the Transcendentals
Whether it is the one he is speaking of,8 the true,9 or the
good,10 St. Thomas is always concerned to point out the
basic identity between being and the transcendentals. Be­
ing and one, for example, do not signify different entities or
natures, but the same nature: unum autem et ens non
diversas naturas sed unam significant. The transcendentals,
in short, do not constitute separate realities; it is the one
reality which they express, namely being. Nevertheless,
while really (in re) identical with being, the transcendentals
are not conceptually identical with it. After all, “to be one”
or “to be good” are not simple tautologies; in both some­
thing is added to “to be,” something said which is not said
by “to be” alone. There is, then, some ground of distinction
between being and the transcendentals; but since the differ­
ence is obviously not in reality, it can only be in the mind, a
distinction of reason. In the case of transcendental one the
distinction (or addition) consists, as we shall see, of a nega­
tion, whereas in the true and the good it is a relation. St.
Thomas makes this point when he writes:
8 Cf. In IV Metaph. lect. 2.
9 Cf. De Verit, q. 1, a. 1, passim.
10 Cf. De Verit. q. 21, a. 1.

The Transcendentals
127
To being, the first conception of the intellect, one adds what
is merely conceptual [rationis tantum]—a negation; for, one
means undivided being. But true and good, which are predicated
positively, cannot add anything except a relation which is merely
conceptual.11
a) The distinction in question must, however, be further
defined. A distinction is real when it exists independently
of the mind, when it pertains to elements of reality of
which one is not actually the other(s). A distinction of
reason, on the other hand, also called logical, exists only in
the mind, i.e. only as product of a mental activity. It occurs,
therefore, when the mind forms different concepts of what
in itself is simply one. But a distinction of reason may have
a foundation in reality; in which case it is said to be a virtual
distinction (Scholastically: rationis ratiocinatae'). If it lacks
this foundation it is a construct of the mind pure and
simple, a purely logical or verbal distinction (rationis ratiocinantis). The distinction of the transcendentals from be­
ing, while not real, has a foundation in reality; it is therefore
virtual.
However, the virtual distinction itself admits of discrimi­
nation. For, the concepts distinguished may be such that one
contains the other(s) only potentially (as genus the species),
which makes for a major virtual distinction. Or, one con­
cept contains the other(s) actually but not explicitly (as
analogue the analogated perfections, and being the trans­
cendental properties), in which circumstances we have to
do with a minor virtual distinction—the answer to the ques­
tion in point, the nature of the distinction between being
and its transcendental properties.
11 Ibid. q. 21, a. 1 c.

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Philosophy of St. Thomas: Metaphysics
b) A further clarification concerns specifically the trans­
cendental true and good, lest they be confused with the
relations which go with them. Though necessarily implied
in each, the relation is not the transcendental. Basically, the
true and the good designate being so far as it has reference
respectively to the cognitive and the appetitive powers,
which means so far as it is determined by the relation to
these powers. Thus, what is signified by the transcendental
true and good is the reality of being itself, but signified as
grounding the order of knowledge and of appetition.

II. THE TRANSCENDENTALS IN PARTICULAR
i. The One

a) Formation of the theory. The metaphysics of the one
has a twofold source. The first is Parmenides, with his keen
sense for the unity of being. Being is, and it is one, so much
so that it admits of no change and no diversity: thus the
Parmenidean idea of it. The other source is the Pythagorean
philosophy, specifically its speculations on the role of num­
ber in the constitution of material realities. Most important
were its views on the role of the numerical unit, principle of
number. Plato draws on both traditions, which also provide
the setting for Aristotle’s theory of transcendental one.
In elaborating his theory Aristotle was above all intent on
securing the distinction between numerical and transcen­
dental unity, a distinction which, though more or less
inherited, he nevertheless saw the necessity of establishing
more firmly. In addition, he was at pains to show that
transcendental one is reducible to being, of which, however,
he clearly saw it was but a property in the sense spoken of
above, and not the essence (as the Pythagoreans had it).

The Transcendental
129
Thus, where the Platonico-Pythagorean school clung to the
idea that number is the essence of things, and plied their
minds (and imaginations) in support of it, Aristotle’s more
perceptive view found being prior to one, a priority he
labored successfully to bring home and which, in effect, left
the whole number-essence idea shorn of foundation.
St. Thomas, in a quite deliberate manner, also begins by
exposing the confusion of numerical and transcendental
unity. Addressing himself to the point he says, among other
things:

Some philosophers failed to distinguish between unity which is
convertible with being, and unity which is the principle of num­
ber, and thought that in neither sense does unity add anything
to substance, and that in either sense it denotes the substance
of a thing. From this it followed that number which is com­
posed of units is the substance of all things : this was the opinion
of Pythagoras and Plato.
Others who failed to distinguish between unity that is con­
vertible with being and unity that is the principle of number
held the contrary opinion, namely that in either sense unity
adds a certain accidental being to substance, and that in con­
sequence all number is an accident pertaining to the genus of
quantity. This was the opinion of Avicenna, and apparently all
the teachers of old followed him; for they did not understand
by one and many anything else but something pertaining to dis­
crete quantity. . . . The above opinions, then, were based on
the supposition that the one which is convertible with being is
the same with that which is the principle of number, and that
there is no plurality but number that is a species of quantity.
Now this is clearly false.12
12 De Potentia, q. 9, a. 7; trans, by Laurence Shapcote, O.P., On
the Power of God (Westminster, Md.: The Newman Press, 1952).

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The confusion and the consequent error of which St.
Thomas here speaks, stem from the failure to grasp the true
nature of metaphysical unity, which consists in the absence
of division, as well as from not having seen that there is a
division which transcends the order of quantity; to this
division, then, is opposed a unity which likewise transcends
that order.13
b) Transcendental unity. For Aristotle and St. Thomas
transcendental unity denotes the nondivision of being, in
other words, the negation of its division. The steps by which
the mind comes to the notion of this unity are outlined by
St. Thomas as follows:
First understood is being, and then nonbeing, and then division,
and then the kind of unity which is the privation of division,
and then plurality, whose concept includes the notion of divi­
sion, just as the concept of unity includes the notion of non­
division.14

As this passage indicates, the concept of “one” designates
none other than being, conceived however as undivided, ens
indivisum. And how is the mind led to conceive of being as
undivided? Through its activity of negation, which in this
case is twofold: negation of being (nonbeing) and negation
of division (one). Thus, what one adds to being is but a
thing of reason, moreover a purely negative thing, a priva­
tion; yet not a privation in the strict sense, which refers to
the absence of a property or quality that the subject ought
to have—as the absence of sight in the case of blindness.
The absence of division in being is obviously not of this
13 Cf. Text III, “Tire Study of the One Pertains to Metaphysics,”
p. 249; Text IX, “One As Principle of Number and One As Trans­
cendental,” p. 270.
14 In IV Metaph. lect. 3, no. 566.

The Transcendentals
131
kind; indeed, it were an absurdity to say that being ought to
have the division which its unity prevents it from having. If
one, then, adds nothing real to being, it follows that they are
really identical, hence also logically convertible. This does
not mean, however, that the two concepts (of being and of
one) are the same, but that the reality to which they point is
the same.
c) Modes of unity. Needless to say, the concept of one
must be, as is that of being, analogous. Since, moreover, its
analogy necessarily parallels that of being, there will be as
many modes of unity as there are of being. St. Thomas, even
as Aristotle before him, made a noticeable effort to reduce
the complexity of them to some order.15 His first distinction
is that of essential and accidental unity—tinum per se,
unum per accidens. Though five modes of per se unity are
advanced, primarily this unity refers to that of substantial
or essential being, as opposed to accidental—a man is one
in substance, though many in accident.16 Accidental unity
results from the union of accidents, or of accident with
substance: musician-mathematician-man constitutes an ac­
cidental unity.
Essential unity, moreover, may be real or logical. If real,
it follows the distinction of the predicaments, where we note
in particular the following: unity of substance (identity),
unity of quantity (equality), unity of quality (similarity or
likeness).
d) Measure: property of the unit.17 Transcendentally
speaking, unity is always defined by the absence of division;
15 Cf. especially In V Metaph. lectt. 7-8; In X Metaph. lect. 1.
16 Of course, an accident has essence too, hence per se unity.
~[Tr.]
17 Cf. In V Metaph. lect. 8; In X Metaph. lect. 2.

1^2
Philosophy of St. Thomas: Metaphysics
this is its essential or most formal nature. The same is true
of the numerical unit, a mode of unity pertaining to the
predicament of quantity; it, too, is most properly defined
by its undividedness. However, with respect to number,
which proceeds from it, the numerical unit has this special
property, that it is the measure of number, measure being
taken for what makes a thing known. How, for example, do
I know how much a certain number is, say the number ten?
Only by comparing it (measuring it) against the unit. That
is why I say it numbers ten, meaning ten units. Thus, the
number 10 is not understood without reference to the unit
that measures it. Nevertheless, the most proper constitutive
of the numerical unit is not that it measures number but
that, like everything one, it is undivided. The absence of
division, that, as we have said, is the first essential of what­
ever unity.
Furthermore, the property of measure, though primarily
vested in the numerical unit, is found proportionally in
other modes of the unit as well. This is readily seen in any­
thing that involves continuous quantity: length, motion,
time. For each of these there is a measure thanks to which
my knowledge of them takes shape—so many yards, so many
seconds, and I know at once how much is meant. But the
notion of measure is not limited to the quantitative order;
analogically it can be applied to other predicaments. And
not to be overlooked is its relevance in the order of knowl­
edge. In a sense, science (and knowledge generally) does
measure reality; but more fundamentally reality is the
measure, for in its capacity as object it measures the facul­
ties of knowledge. All in all, the notion of measure has
many important applications; while derived from the rela-

The Transcendentals
133
tion of number to the unit, its service to the mind goes far
beyond that.
c) The many: opposition to the one.16 Just as unity follows
on the notion of nondivision, so plurality or multiplicity
follows on the notion of division. The multiple is simply
divided being. Between one and many (or divided being)
there is, as mentioned earlier, an opposition of privation.
The “one” implies privation or absence of division, the
“many” privation of nondivision. Hence, to every mode of
unity corresponds a mode of multiplicity. There is, how­
ever, an important distinction to be kept in mind concern­
ing multiplicity itself; namely between numerical multi­
plicity, which is number and therefore limited to the
predicament of quantity, and transcendental multiplicity,
which pertains to every mode of being as divided. Nor, in
its more general sense, should transcendental multitude
(multiplicity) be identified solely with multitude as it ap­
plies to separate substances (angels), which constitute but
one kind, albeit pre-eminent, of transcendental multitude..
Finally, we take note of a possible difficulty. One, we
have said, is defined as absence or privation (in the large
sense) of division, hence of multiplicity. It would seem,
then, that the many (the multiple) is prior to one; if so, one
could hardly be the measure or, in any way, the principle of
the many. There is no doubt (in reply) that negation of
division is the very essence of unity; however, the division
which is negated does not yet imply the formal or express
recognition of multitude as such. This recognition can
come only after the mind has adverted to the unity of each
member of the group. Consequently, the true sequence in
18 Cf. In X Metaph. lect. 4.

Philosophy of St. Thomas: Metaphysics
the formation of our first notions is as described by St.
Thomas, to wit:

First apprehended by our intellect is being, and then division,
and next unity, which is the privation of division, and finally
multitude, which is a composite of units. For even though
things which are divided are many, they do not have the formal
note of a many until the fact of being one is attributed to each
of the particular things concerned.19
2. The True
a) Formation of the theory. This transcendental presents
a more complex pattern, since the true—as also the good—
denotes being, not in itself, but in relation to another.
What is truth? is an age-old question. Offhand, most men
would agree that it is the goal of all knowledge, the desire
and perfection of the intellect: we seek knowledge because
we seek truth. To speak of truth as the perfection of the
intellect is to speak of it as in the subject, hence from the
subjective point of view—a valid conception. As a matter of
fact Aristotle conceives of it mostly in this way. St.
Augustine, doctor par excellence of the philosophy of
truth, reverses the perspective; and the tradition that at­
taches to his name has faithfully followed him. Truth in the
Augustinian sense is in the object, or rather is an object that
dominates and imposes itself upon the mind. Primarily and
most properly this conception refers to the divine truth,
eternal and immutable, in which created intellects partici­
pate. St. Thomas, heir to both traditions, undertook to
reconcile them. For him, truth was indeed the perfection of
the intellect, it was in the subject; but it was also in the
10 In X Metaph. lect. 4, no. 1998.

The Transcendental
135
object, an objective property of being deriving ultimately
from the divine knowledge rather than the human. Truth,
in short, was both logical and ontological.
b) Logical and ontological truth in formula. Truth always
implies a relation between being and intellect. But the rela­
tion can be considered from either of its terms, either as
based in the intellect or as grounded in being. Truth is in
the intellect or, an intellect is true when its act (of knowl­
edge) conforms with being, with what is.20 True knowledge,
then, is knowledge which bears a relation of conformity
with its object, with reality. Thus understood, truth is de­
fined as the conformity of intellect to thing: adaequatio
intellectus ad rem; which, by common accord, is the defini­
tion of logical truth. Conversely, from the objective point
of view, truth is in things or a thing is true in proportion to
its conformity with the intellect. This is ontological truth,
the conformity of thing to intellect: adaequatio rei ad
intellectum. Both definitions (formulas) must be looked
into further.21
c) Logical truth. Truth, in the primary sense, is in the
intellect or, more generally, in the faculty of knowledge;
and, as we have seen, it arises when (and in the measure
that) the faculty is conformed to the thing. But the con­
formity exists on two levels, so to speak. For the intellect is
already conformed to the thing in the act of simple appre­
hension, and the sense faculty is conformed to its object in
the act of sensation. But neither the intellect at this mo20 This, in effect, is Aristotle’s definition of (logical) truth—
verbatim, “to say of what is that it is, and of what is not that it is
not, is true” {Metaph. r, 7, ion b 27).—[Tr.]
21 Cf. Text X, “Logical Truth and Ontological Truth,” p. 272.

ij6
Philosophy of St. Thomas: Metaphysics
ment, nor the sense at any time, knows its conformity.
Through its power of reflection, however, the intellect is
capable of passing judgment upon its knowledge by com­
paring its apprehension with the thing apprehended, and
thus it becomes aware of the conformity with its object.
So that it is in judgment (the second operation of the
mind) that the intellect comes in possession of truth as a
known or recognized conformity; which, for the intellect,
is obviously a more perfect state of affairs than the unrecog­
nized conformity in simple apprehension. Logical truth is
precisely the truth as known, the conformity that has en­
tered the awareness of the intellect. Scholastics speak of this
state of truth as formal; whence their conception that truth
is formally in judgment rather than in simple apprehension.
On which matter St. Thomas deserves to be quoted at
length; his doctrine, it will be seen, squares perfectly with
the above:
Truth is defined by the conformity of intellect and thing;
hence to know this conformity is to know truth. But in no way
does sense know this. For though sight has the likeness of a
visible thing, it does not know the comparison which exists
between the thing seen and that which it itself is apprehending
concerning it. But the intellect can know its own conformity
with the intelligible thing; yet it does not apprehend it by
knowing of a thing what a thing is [simple apprehension].
When, however, it judges that a thing corresponds to the form
which it apprehends about that thing, then it first knows and
expresses truth. This it does by composing and dividing [i.e. in
judgment]: for in every proposition it either applies to, or re­
moves from, the thing signified by the subject some form signi­
fied by the predicate. So, then, the sense is indeed true in regard
to a given thing, as is also the intellect in knowing what a thing

The Transcendentals
137
is; but it does not thereby know or affirm truth. . . . Truth,
accordingly, may be in the sense, or in the intellect knowing
what a thing is, namely, as in something that is true, but not
as the thing known is in the knower, which is what the word
truth implies. Yet the perfection of the intellect is truth as
known. Properly speaking, therefore, truth resides in the intellect
composing and dividing, and not in the sense or in the intellect
knowing what a thing is.22

d) Ontological truth. This is truth as inhering in things,
as a transcendental property of being. Its definition still
includes reference to intellect, for truth of whatever kind
implies a relation to intellect. But again the occurrence is
twofold. The reference, namely, may be to an intellect upon
which the thing in question depends for its existence, as the
work of art upon the artist, and more properly, all creation
upon the Creator; or it may be to an intellect which must
bend to the thing it knows as to its object. Ontological
truth refers, essentially, to the first mentioned, to the in­
tellect upon which things depend, in the final count to the
creative intellect of God. Primarily, then, ontological truth
is simply the conformity of things to the divine intellect, all
things having been preconceived by God and made to his
knowledge.23 In a less proper sense, however, things may
also be said to be true from their relation to an intellect
22 Summa theol. la, q. 16, a. 2; English Dominican translation,
edited and annotated, with an Introduction by Anton C. Pegis in
Basic Writings of Saint Thomas Aquinas, Vol. I (New York: Ran­
dom House, 1945).
23 In a derivative sense we may, possibly, speak of ontological
truth in respect of the human intellect; for while this cannot pro­
duce the nature of things, there is practically no limit to the ways it
can fashion and refashion the things that nature supplies.—[Tr.]

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Philosophy of St. Thomas: Metaphysics
(created, to be sure) upon which they do not depend. But
this is an accidental relation as far as things are concerned,
and to say that things are true in this accidental sense means
simply that they have an aptitude to be an object of knowl­
edge for a speculative intellect, for example that of man.24

In summation, truth is found:
—formally and principally in the intellect when in
judgment;
—in the sense and in simple apprehension, on the same
score as it is in all things true;
—in things, essentially by reason of their respective con­
formity with the idea according to which God creates them;
—in things, accidentally through relation to the specula­
tive intellect, because it can (but) know them.
e) The false. Along with the true St. Thomas, not inap­
propriately, studies its opposite, the false. To be noted,
among other things, is that there can be no transcendental
or ontological falsity in the absolute sense; for this would
mean that a being escapes the creative causality of the
divine intellect, an impossible eventuality. Absolutely speak­
ing, then, (which means in relation to the divine intellect)
being cannot be false. In reference to the created intellect,
however, (and specifically to the human) things may be
said to be false when by their appearances they invite mis­
conception of their true nature. So, for example, we speak of
false gold; yet the reality in question is not false but true—
true copper, true bronze, or whatever it truly is. Actually,
to speak of things in this way is just that—a manner of
speech, albeit a legitimate one.
24 Cf. Summa theol. la, q. 16, a. 1.

The Transcendentals
139
But if ontological falsity is not strictly possible, logical
falsity, as everyone can testify, is only too common. Like
logical truth, logical falsity exists in the mind, and formally
in judgment, which is false when it says of what is that it is
not, and vice versa. As for the senses, and also the intellect
in simple apprehension, these are always true, at least in
regard to their proper object.
Appendix: The principle of sufficient reason

In connection with the intelligibility (which is the mean­
ing of the truth) of being many authors discuss a principle
not found in so many words in St. Thomas, that of suffi­
cient reason, usually stated as “every being has a sufficient
reason.” The principle, in its modern development, must
be credited to the rationalism of Leibniz, since when it has
loomed large in many philosophical minds. And for all that
one searches St. Thomas in vain for mention of it, the prin­
ciple does bear an interpretation (though not the Leibnizian
one) that fits it fairly into his thought.
The first approach is by way of another axiom, that
“every being is true,” which, no one doubts, is authentic St.
Thomas. Every being, this means, is by its very nature or­
dered or proportioned to an intellect; hence “every being is
true” has the meaning of “every being is intelligible.” Not
every being, however, is intelligible through and through, or
perfectly. The intelligibility in question is perfect only if
the being in question is perfect, or perfectly being; which,
of course, is God, perfectly intelligible in himself—not, need
we say it, to us. Created beings, compacted as it were of
being and nonbeing, are in some measure shrouded from the
intellect; which is to say, to such beings there necessarily

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Philosophy of St. Thomas: Metaphysics
clings a greater or lesser degree of opacity, of unintelli­
gibility. Our principle, then, does not mean that from the
mere notion of being can be deduced the whole content of
reality; nor, more to the point, that all reality yields itself
perfectly to every speculative intellect. Such optimism,
which characterizes certain forms of philosophical rational­
ism, is not justified by the facts. Extreme interpretation of
this kind will be precluded if we give the principle the
fuller formulation that “every being is intelligible so far as it
is being.”
If being is intelligible, there must be a ground for its
intelligibility. This ground is precisely its “sufficient rea­
son,” that which both determines being to be and renders
it intelligible. Every being, accordingly, is intelligible be­
cause for every being there is a sufficient reason, something
that adequately accounts for what it is or has.
Tire sufficient reason, to go a step further, may be within
a being, flowing as it were from its very nature or essence.
The square, for example, or the color red are what they are
because of their essence, which constitutes them what they
are. This is plain in the case of the square; you cannot
define it (which is to give its essence) without mentioning,
among other things, its sides. But the sufficient reason of
being is not always in a being itself or in its essence. If a
man is white, this does not result from his essence, or all
men would be white. In such cases, then, the being in
question must have its sufficient reason in another, which
will be its cause. As St. Thomas puts it, “Whatever belongs
to a thing, but not as following from the thing itself, be­
longs to it through some cause, as white to a man.” Which
is the sense of,

The Transcendentals

iqi

Omne quod alicui convenit non secundum quod ipsum
est, per aliquam causam convenit ei, sicut album homini.

And why so? Because, continues St. Thomas, “that which
has no cause is something first and immediate; hence it is
necessary that it be by reason of itself and in consequence
of what it is,”—the rendering of,
Quod causam non habet, primum et immediatum est;
unde necesse est ut sit per se et secundum quod ipsum.25

Being, accordingly, is what it is either by self and by essence,
or by another. Whence we conclude the principle as follows:
“Every being, as being, has its sufficient reason in itself
or in another.”

This formulation, it is worth noting, covers both orders
of being; both essence and existence; however, we have
already as much as said that the sufficient reason in one
order is not the same as in the other. So, in the order of
essence the principle says (in effect) that properties have
their sufficient reason in the essence of the subject to which
they pertain—for example, that the interior angles of a
triangle equal two right angles stems from the very nature
of this figure, and the fact of man’s aptitude for instruction
is a consequence of his rational nature. In the order of
existence (or concrete being) the sufficient reason is a cause
in the more proper sense of the word. Any being which does
not exist of itself (hence a contingent being: this stone, this
tree, etc.) has its sufficient reason in another as in its cause;
and since causality is not all one kind, the sufficient reason
will vary according to the line of causality. What we are
25 Contra Gentiles, II, 15.

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Philosophy of St. Thomas: Metaphysics
saying, then, is that the principle of sufficient reason is an
analogical principle and that its application must in conse­
quence be analogical, varying with the orders of being and
the types of causality. To forget this is to invite the extremest apriorism, a rationalism untempered by realism.26
3. The Good

a) Formation of the theory. With the good, as with the
true, St. Thomas found a twofold tradition, the Platonist
and the Aristotelian. According to the Platonist conception,
which was to persist in the Augustinian school, the good is
to be understood as a transcendent principle, existing apart
from the material world. Given this premise, it was more
or less inevitable that the Platonists should also hold the
good to be prior and hence pre-eminent to being. The
Aristotelian tradition, in line with its more realist orienta­
tion, takes the more familiar view, conceiving of the good
as a perfection inherent to the things of experience. St.
Thomas’ contribution, again, would be one of synthesis;
specifically, it was to be an accommodation of Platonist
tenets to the Aristotelian scheme of the good.
b) Nature of the good. At the beginning of the Nicomachean Ethics Aristotle, in a well-known context, defines
(or rather endorses the definition of) the good as that to­
ward which all things tend : quod omnia appetunt—literally,
“what all things desire.” 27 Thus the basic thing about the
good is that it bears on (and stirs) the appetite. If, as we
26 For further discussion of the principle of sufficient reason see
the excellent treatment of R. Garrigou-Lagrange, O.P., God: His
Existence and His Nature, Vol. I, pp. 181-191 (St. Louis: B. Herder
Book Co., 1934. Seventh Printing, 1955).—[Tr.]
27 Cf. Ethica Nie. I, 1, 1094 a 2.

The Transcendentals
143
have seen, the true denotes a relation of intellect to being,
the good for its part denotes a relation of being to the
appetite—statements which but give philosophical expres­
sion to matters of common and indeed universal experience.
But whereas the true resides primarily in the faculty of
knowledge, the good lies basically in the thing; is, as a
matter of fact, the thing itself considered as founding the
property of appetibility.
That every being has the nature of good, or that the good
is a transcendental St. Thomas establishes in the following
manner. The good is what all things desire; but a thing is
desired according as it is perfect; it is perfect, however, so
far as it is in act; and it is in act in the measure that it is
being. Conclusion (which necessarily follows): good and
being are the same reality. But they are not the same in
thought or concept; for the good conveys the formality of
appetibility, which is not explicitly said when we say “be­
ing.” St. Thomas gives all this in the following passage:
Goodness and being are really the same, and differ only in
idea; which is clear from the following argument. The essence
of goodness consists in this, that it is in some way desirable.
Hence the Philosopher says: Goodness is what all desire [Eth.
I,r, 1094 a 3]. Now it is clear that a thing is desirable only in
so far as it is perfect, for all desire their own perfection. But
everything is perfect so far as it is actual. Therefore it is clear
that a thing is perfect so far as it is being; for being is the ac­
tuality of every thing, . . . Hence it is clear that goodness and
being are the same really. But goodness expresses the aspect of
desirableness, which being does not express.28
28 Summa theol. la, q. 5, a. 1. (trans, from Pegis, Basic Writings,

etc. See note 22).

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Philosophy of St. Thomas: Metaphysics
Act, perfection, good: three aspects of being with mean­
ings which, though not identical, are nevertheless so closely
related that the thought of one suggests the thought of the
other(s). And since in reality they are the same as being, it
necessarily follows that being and good are convertible.29
c) The good as final cause?0 Another related notion of the
good is that of final cause. Clearly, whatever a thing desires
as final cause can only be a good for it; conversely, every
good can assume the formality of final cause. “Since the
good,” in the words of St. Thomas, “is that which all things
desire, and since this has the aspect of an end, it is clear that
goodness implies the aspect of an end” [i.e. final cause].31
In short, the order of good coincides with that of finality—
a self-evident truth once we know the meaning of “good”
and “final cause.”
It is also true that final causality does not act in isolation;
it implies both efficient and formal causality, the formal
as principle of the efficient. Nevertheless, the causality
proper to the good precisely as good is final causality, which
consists in evoking desire. Hence it is along the line of final
causality that we must understand the accepted expression
that “good is self-diffusing” (or “self-radiating”): bonum est
diffusivum sui. The diffusion or radiation is not to be taken
literally, like the emission of light from a body; which is to
say it is not an activity of efficient causality. But, it might
be asked, does not final cause or the good (it is all the same)
have the status of an unmoved mover; and if so, does not
this indicate an exercise of efficient causality? The answer
29 Cf. Text XI, “Whether Good Adds Anything to Being,” p. 274.
30 Cf. Summa theol. la, q. 5, a. 4.
31 Ibid.

The Transcendentals
145
is that they are indeed unmoved movers, but only when
they are strictly themselves, i.e. only so far as they determine
and govern the activity of the appetite.
d) Kinds of good. Since good is convertible with being its
concept, like that of being, will be analogical; and for every
particular being there will be a corresponding good. Accord­
ing to a classical division, which goes back to St. Ambrose,
good is of three kinds: the perfective, the useful, and the
pleasing (or satisfying) good.32 Correctly understood this
division is exhaustive. Good is the object of the appetite, or
that which is desired. But what is desired is either a means
to a further end, or it is itself the desired end. If the desired
good is a means, it falls under the useful: bonum utile. If,
on the other hand, the good is itself the desired end, two
points of view emerge. Either the good in question refers to
the object in which the movement of the appetite termi­
nates, giving us the perfective good: bonum honestum—or
it designates the subjective possession of this same object,
the “quiescence upon attaining the desired thing,” and thus
is the pleasing good: bonum delectabile. There is no good
that does not fit this classification. But we must not, among
other things, read too much into the notion of “perfective
good,” which is not necessarily the all-perfect good (though
that is included) but any good in which the appetite comes
32 Which translate the Latin honestum, utile, and delectabile re­
spectively. Doubtless, the expression bonum honestum has been the
despair of many a translator, and the rendering “perfective good”
may well be questioned. Others have represented it as the “virtuous,”
or the “disinterested,” or the “autonomous” good—and the list
could go on. But however one gives it, bonum honestum will stand
a lot of exegesis when it comes to teaching the underlying notion.
-[Tr.]

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Philosophy of St. Thomas: Metaphysics
to rest. Even so, good in the primary sense is the perfective
good, to which the useful is related as means and the pleas­
ing as complement. The pleasing good, moreover, refers
properly to beings endowed with affectivity (i.e. intellectual
and/or sensory appetition) but is attributed analogically
to other beings as well.
e) Evil: the opposite of good. Evil is a many-sided prob­
lem, far too complex to do it justice here. We should, how­
ever,—and that is all we intend—state the general position
of St. Thomas as to the nature (loosely speaking) of evil, a
position which follows logically from his conception of its
opposite, the good. Opposites, as St. Thomas observes, can
generally be known one through the other, as darkness
through light. Evil, then, will be known from the nature of
good. Now good is convertible with being; hence every be­
ing has the nature of good. Thus evil, the opposite of good,
cannot be a positive being; it can only refer to some absence
of being, (which means) of good.
It is impossible [concludes St. Thomas] that evil signify any
being, or any form or nature. Therefore, by the name evil must
be signified some absence of good. And this is what is meant
by saying that evil is neither a being nor a good. For since being,
as such, is good, the absence of being involves the absence of
good.33

However, not just any absence answers to the meaning of
evil; it has to be the absence of a modality of being which,
considering the nature of a thing, should be present—so, to
be wingless is not an evil for man but would be (say) for a
robin. In formal idiom such an absence is a privation: the
“ Summa theol. la, q. 48, a. 1.

The Transcendentals
147
lack of a due perfection (as is commonly put). An immedi­
ate deduction from this is that absolute evil is impossible;
for, presupposing as it does a subject, evil always rests on
something positive, which, because it is being, cannot but be
good. Perhaps not so evident but just as true is that evil
cannot be desired for its own sake, or precisely as evil. An
appetite must always bear on what is (or presents itself as)
good; and if it seems to be directed toward evil, this on
examination will prove to be either an apparent or an in­
cidental evil: the appetite is seeking a good to which some
evil attaches. In short, only the good has the nature and
aspect of desirability: solum bonum habet rationem appe­
tibilis.

Appendix: The principle of finality
In the volume on the philosophy of nature (cosmology)
we had occasion to speak of finality under the causes of
mobile being.34 But finality, it should be noted, operates not
only within the area of nature; it is rooted in being uni­
versally, has therefore a metaphysical basis; which is the
reason for returning to the subject now. A final cause (to
proceed metaphysically) corresponds to a good; conversely,
every good has the nature or formality of an end. This was
made clear some paragraphs back. We have also seen that a
being can only act for (which is to say, desire) a good; its
every assertion, its every tendency is for a good, and if a
good then an end. And this, in effect, is what the principle
of finality says, that “every agent acts for an end”:
84 Cf. Volume II of the present series, namely Cosmology, chapter
5; trans, by John A. Otto (St. Louis and London: B. Herder Book
Co., 1958).

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Philosophy of St. Thomas: Metaphysics
omne agens agit propter finem.
This principle can be substantiated in several different
ways, and on different levels of thought. But the basic
reason why there must be an end for every action is the
metaphysical reason that potency cannot determine itself.
If there is to be action from an agent in potency, this
potency must be determined, and determined to some defi­
nite thing. Now, it is all the same whether we say an agent
is determined to some definite thing, or that the agent is
acting for an end. St. Thomas gives this train of thought in
these (much the same) words:
An agent does not move except out of intention for an end.
For if the agent were not determined to some particular effect, it
would not do one thing rather than another. Consequently, in
order that it produce a determinate effect it must, of necessity,
be determined to some certain one, and this will have the na­
ture of an end.35
Thus, what comes into play here is, once again, the cardinal
thesis of metaphysics that potency stands in essential (tran­
scendental) relation with act, or (same thought) that
potency is determined by act.
One further remark. Like any metaphysical principle, that
of finality is analogical, true of all beings but in proportion
to their nature, as St. Thomas in the above-mentioned con­
text goes on to show.38 Finality in inanimate beings is one
thing, for they do not move themselves to the end but are
moved. Significantly different, yet not wholly, is the like
exercise in rational beings, who know and move themselves
35 Summa theol. la Ilae, q. 1, a. 2.
36 Summa theol. art. cit.

The Transcendentals
149
to the end. But greatest of all is the incumbent adjustment
of the principle when said of the Deity; for God, properly
speaking, does not act out of desire of the end—this would
imply a want of goodness—but only from love of the end
that is his own infinite goodness.37

III. CONCLUSION: THE TRANSCENDENTALS
AS A SYSTEM
a) Do the transcendentals of Thomistic philosophy con­
stitute a system, a complex of ideas bound together by their
own inner logic? In point of fact the exposition of the
metaphysical properties of being which we have just con­
cluded did not proceed deductively; recourse to experience
or to some basis in reality was involved in the study of each.
Notwithstanding, once ascertained the transcendental
properties do emerge as a system, a coherent and wellordered assembly of thought in which necessary sequences
of ideas are clearly discernible. These sequences, in the
order in which they have been noted earlier, are the
following:

being — nonbeing — principle of noncontradiction
being (as existent) — being (as essence) — principle of
identity
being — divison — one — many
being — one — true
being — act — perfect — desirable — good
If we now ask ourselves what it is that leads the mind to
the formation of each train of ideas as given above, the
answer proves most revealing. Each procession of ideas, it
37 Cf. In II Sent. dist. I, q. 2, a. 1.

i$o
Philosophy of St. Thomas: Metaphysics
will be found, is commanded by discoveries of distinction or
opposition—opposition not all of the same degree, however,
but ranging from pure contradiction to mere relation. This
points to opposition, or the mind’s recognition of it, as an
essential factor of intellectual life, the occasion (if not the
stimulant) of intellectual growth and development. The
idealists Hegel and Hamelin, we might note, were to per­
ceive and pursue this theme unwaveringly. But a realist
philosophy, too, is nurtured by the perception of opposition.
Yet there is a difference; for in a realist philosophy the
opposition conceived by the mind always relates to reality
and does no more than reflect the antithetical diversity
contained in reality.
b) Granted, then, that the transcendental make a system,
what are its most notable characteristics? Above all it is, as
just intimated, a realist system; more precisely, it is founded
on the primacy of the notion of being, which but mirrors
the primacy of being itself. Pythagorean and Platonist
thought had always a marked propensity for giving priority
to the Good or the One and conceiving them as separate or
earth-shorn principles of which the things of earth were but
remote participations. In St. Thomas, on the other hand,
the prior (and first) experience is being, which is to say
reality under the aspect of being, and good and one for their
part are not given separate existence but become properties
of that which exists, namely being. This view of the matter
does not, of course, rule out a Being with the attributes of
unity and goodness which gives being to all other things
through a manner of participation; St. Thomas, as a matter
of fact, adopts the principle of participation. But far from
jeopardizing the metaphysical substantiality of things ter-

The Transcendentals
151
rene, participation in the Thomistic context tends rather to
assure it.
On both counts, then, we have to do with a realist system
of transcendentals; not only is it founded on being (reality),
but the reality of experience (our world) is truly being.
Furthermore, the realist universe of St. Thomas is thor­
oughly integrated; for, thanks to the convertibility of the
transcendentals, the order of thought and action (presided
over respectively by the true and the good) come together
in being, ultimately in the first being, where unity and
truth and goodness attain absolute identity with being
itself.
c) Further characterizing the metaphysical realism of St.
Thomas is a certain intellectualism; the true takes onto­
logical precedence of the good. St. Thomas is very explicit
on this point. There is, he says, an order among the tran­
scendentals. Being is first, then one, next the true, and last
the good. Or, as St. Thomas puts it:
The order of these transcendent names, accordingly, if they are
considered in themselves, is as follows: after being comes the
one; after the one comes the true; and then after the true comes
good.38

The true, then, as St. Thomas reiterates over and over, is
prior to the good. Two reasons lead him to this conclusion.39
First, compared with the good the true stands in closer asso­
ciation with being, which itself is prior to the good. For the
true relates to being in itself or absolutely, whereas the
formality (ratio) of good results from being according as it
38 De Verit. q. 21, a. 3 c.
39 Cf. Summa theol. la, q. 16, a. 4 c.

i^2
Philosophy of St. Thomas: Metaphysics
is perfect. To which St. Thomas adds this second considera­
tion, that knowledge naturally precedes appetition. Thus,
whether in activity or in object, the order of truth stands
prior to the order of good. The implications of this position
of St. Thomas appear at every turn; for the position is
cardinal to his thought, governing every principal orienta­
tion. And it reverts, as we have now seen, to the very first
discoveries of metaphysical inquiry.

t CHAPTER 5

The Predicaments

t SO far we have studied being in itself and those
modes of it (the transcendental properties) which occur in
being universally. With the predicaments—the term “cate­
gories” is also much used—we embark upon the study of
being in its particular modes, which (as against the uni­
versal modes) are really distinct from each other and do not
necessarily follow on being simply because it is being. Of
these, therefore, we cannot say they are convertible with
being.
That there are a number of such modes Aristotle re­
garded as self-evident. Inductively (consulting experience)
he found that the supreme or ultimate genera of being
(which are particular modes) came to ten, an enumeration
that was to win lasting acceptance among his followers.
These ultimate genera, or predicaments, divide first of all
into substance and accident, substance denoting being
which exists in itself, and accident being which can only
exist in another. There are nine distinct modes of accident:
quantity, quality, relation, action, passion, place, position,
time, and possession.

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Philosophy of St. Thomas: Metaphysics
As was brought out in the chapter on analogy, the pre­
dicaments are analogical modes of being. As a matter of
fact, Aristotle regarded them as the typical case of the
analogy of attribution, in illustration of which health is
perennially, and aptly, cited. Medicine, complexion, and
so forth are said to be healthy because of their relation to
health as it exists in a living thing, specifically in the bodily
organism, which alone possesses it formally or properly.
Similarly, the various accidents are said to be being by virtue
of relation to substance, which is more perfectly being than
accidents. But being, as we know, is also analogous by pro­
portionality; consequently, the being of accidents too is
being in a formal or proper sense, and not by mere denomi­
nation. For all that, however, the primary and fundamental
being of the predicamental order is substance, and that is
why we shall give it more attention.
Some incidental matters should first be set down. In their
totality (for one), the predicaments cannot be said of every
order of being, but only of material beings. Quantity and
whatever relates to quantity has obviously no place in the
world of spiritual substances. And (for another), the pre­
dicamental division of being as St. Thomas conceives of it
applies only to creatures; God remains outside or above it.
Hence to define him as a substance, while not unheard-of,
is none the less unsound—though even Aristotle is some­
what less than clear on the point.

I. SUBSTANCE
i. The Existence of Substance

The existence of substantial beings, or substances, is
accepted without question both by Aristotle and St.

The Predicaments
155
Thomas, and there is no indication they ever thought or
were even tempted to think otherwise. For them, then,
substance is (or comes to) an evident fact, at least in the
sense that experience reveals it almost immediately, with
little or no sifting required. Yet modern philosophy, from
Locke down, sees nothing but difficulties in the thought of
substance and soon arrived at the point where, as though
by custom decreed, its denial was a matter of course. What
are these hurdles that seem so insurmountable?
By definition, or of its very nature substance (it is said)
lies beyond the senses; this alone should render its existence
suspect. Behind this mistrust there broods of course the
epistemological doctrine that all knowledge is of appear­
ances and cannot overreach them. Since you can only know
(runs the contention) what falls to the senses, to hold for
the existence of substance is utterly arbitrary and unwar­
ranted, if not indeed contradictory.
But granted (continues the argument) that common
sense points to the existence of this latent, inert subject out
of which the philosopher fashions his notion of substance,
this proves nothing. Common sense is here led astray by a
circumstance of the logical order, that every proposition
has a subject; which no one denies, but it does not follow
that things in reality must have one, too. In fine, those who
put forth the metalogical subject, which is substance, are
guilty of unwarranted reification, converting the logical
subject of the proposition into a real subject of appearances.
This and more has been laid against substance. Yet for the
most part, as we shall see, modern philosophy’s attack
against it falls wide of the mark, having addressed itself in
no small measure to misconceptions. Still, the effort was not

i$6
Philosophy of St. Thomas: Metaphysics
entirely wasted on followers of St. Thomas, for it obliged
them to take a closer look at their doctrine of substance the
better to maintain the ground on which it rests.
a) The simplest and most obvious way to substance is by
examining that most common occurrence, change. Given in
knowledge is a world of multiplicity with variety; not only
are things many, but many-sided as well. Some aspects of
these things change constantly, others appear more lasting.
Water, a familiar example, goes from cold to hot, and con­
versely. As the temperature rises no one doubts that the
water remains water. We could not even conceive of it as
becoming warmer and registering a change of degree on the
calorimetric scale unless it remained the same water. No
matter how much it changes, if nothing remained from the
original water, then what is now hot would not be the same
water that was cold. Yet common sense tells us it is the
same, though not the same temperature. Thus, the notion
of change necessarily implies the notion of subject or sub­
strate, a thesis set forth at great length in Aristotle’s classic
analysis of the principles of nature.
It is true, of course, that what is subject of change may,
at another time or in another respect, be the thing that
changes, in which case we must look for a further subject,
anterior to the first. But the anteriorisation of the subject
cannot go on indefinitely; the succession must come to an
ultimate subject, one that is essentially (by nature) subject.
It is precisely in this way, by tracing the course of change to
its ultimate ground, that Aristotle makes his case for prime
matter, which in a way is prior even to substance. For the
present purpose we need not carry the analysis all the way
back to prime matter. The issue here is substance, the

The Predicaments
157
existence of which is proclaimed by those lesser changes
called accidental, for they are simply unintelligible without
an abiding substrate, abiding and (unlike prime matter)
already determined of nature. Every change, in short, which
leaves the essential nature of a thing unchanged supposes
the persistence of the nature, supposes, that is, substance.
b) The demonstration of substance through the analysis
of change is unquestionably valid. All the same, it does not
bring directly to light what is most essential to substance;
nor is it from this angle that Aristotle in the Metaphysics
approaches the study of this (the first) predicamental being.
Here, in the main, is what he says at the beginning of
Book Z:

Being has several meanings. On the one hand it means es­
sence and the determined individual; on the other hand it sig­
nifies that a thing has this quality or this quantity or any of the
like predicaments. But though there are these many meanings
of being, it is obvious that being, in the primary sense, is the
essence, which indicates the substance of a thing. . . . Other
things are called being only because they are quantities of being
in this primary sense, or qualities of it, or affections, or some
similar determination of it... . Thus it is clearly by this category
that the other categories each exist. Consequently, being in the
fundamental sense, not this or that mode of it but being without
qualification, must be substance.1
In Aristotle’s view, accordingly, substance has not only
the status of substrate but also the position of primary
being, of principle of existence (in some respect) for the
other modes of being. The passage just cited brings this out
What may be overlooked, yet is of great significance, is the
1 Metaph. Z, i, 1028 a 10-30.

i$8
Philosophy of St. Thomas: Metaphysics
controlling factor behind the thought of the passage; it is,
once again, the analogical character of being, which for
Aristotle is essentially an analogy of attribution. The mo­
dalities of being are many; this is fact. But the multiplicity
is unintelligible, unaccountable, unless it have some com­
mon bond or unity; to have this unity it must be brought
together under some first term, which in this case will be
the first and essential mode of being (at least within a
certain order of things). Such is substance, which in this
perspective comes out more than substrate; it comes out as
principle that renders unity and thereby intelligibility to the
data, the multiform data, of reality.
c) In the light of what has now been established we can
formulate an answer to the contention that substance is a
fictitious entity or (if that is going too far) that it does not
yield to perception, since this takes in only appearances,
accidents. This criticism needs correction on the data of
perception. What is immediately given in perception is
neither appearances (phenomena) in the subjectivist sense
nor substance as such; it is rather the concrete individual
being embodying both substance and accidents in one in­
discriminate whole. Thereafter, by analysis, we discern one
from the other, the concourse of various and varying mo­
dalities from the unvarying substrate or substance. Not that
substance as such meets the sense, but that which meets
the sense, the concrete individual with its fluctuating mo­
dalities, has no intelligibility without recourse to substance,
the substrate and primary being in one; in this the complex
of accidents finds a rationale, a standing in reason as well as
in reality. All which comes to this: that substance, while not
an immediate perception, is an immediate inference—a
necessary one, at that.

The Predicaments
159
This conclusion leads on to another, also highly impor­
tant. That substance exists is evident, in the sense we have
just explained; but which thing in nature is an individual
substance and which is not, we do not know with the same
immediacy. As a matter of fact, read strictly the foregoing
analysis compels the existence of but one created substance.
Nevertheless, the plurality of substance is far more in
conformity with the presentations of experience. Thus, it
seems virtually impossible to deny substantial individuality
to living things and, though here the thing is less clear, to
ultimate elements of the inorganic kingdom.
Finally, we come to the objection that substance is but
an unwarranted transposition of a circumstance of logic into
a circumstance of reality. Against this we urge the following:
when you analyze the judgment aright, you find that the
modes of predication correspond with factual, not fictitious,
modes of objective being. Logic corresponds with reality
because the predications of logic are conditioned by objec­
tive determinations of being, and not the other way round.
The predicaments, in short, and therefore substance, have
existential import as well as logical signification.

2. Nature and Properties of Substance2
a) Nominally, substance (from sub-stare: to be under)
means that which is under the appearances or accidents,
hence serves as their subject. But though substance gives
accidents their support, this property, as is the way of
properties, does not express what is most basic to it, its
essence. Aristotle comes closer when he writes: “Substance,
in the truest and most rigorous and primary sense of the
word, is that which is neither predicated of a subject nor
2 Cf. in particular Aristotle, Categories, chap. 5.

16o
Philosophy of St. Thomas: Metaphysics
is in a subject.” 3 This definition, though indicative of the
essence of substance, describes it negatively, a “not-being
in a subject”—non esse in subjecto. Since substance, evi­
dently, is a positive perfection, it is more aptly denoted by
the expression “to be in itself”—esse in se.
Substance, then, can be conceived under various aspects,
and all of them come into play in the mind’s discovery of
what it is. Our first idea of it is as support of accidents, then
as not being in another, and then as being in itself. Yet all
this still leaves us short of the true essential, the formal
constitutive, of substance. For, a predicamental division of
being (and such is substance) is not defined by its existence
but by its quidditative principle or essence. Since, then,
existence is not of the essence of a predicamental being, to
be perfectly correct we should define substance, not as that
which actually exists in itself but “that which is equipped
(aptum) to exist in itself and not in another as inhering in a
subject.” In Scholastic idiom:
quod aptum est esse in se et non in alio tamquam in
subjecto inhaesionis.

In addition, substance is sometimes spoken of as “self­
being” or “being by itself” (per se ens), and “perseity” or
self-beingness as its formal constitutive. This terminology
is acceptable provided that the “by itself” be not taken in
the causative sense. Strictly speaking, the only ens per se,
being that exists by itself, is God. Substance is “by itself”
only in the sense that it has everything it needs to receive
existence. To receive existence, however, is to have it not
in virtue of (or by) oneself but in virtue of another. We
3 Categories, 5, 2 a 11-12.

The Predicaments
161
must not, then, read the full force of the word into the
“perseity” of substance; the logical outcome would be
pantheistic monism, an eventuality well exemplified in
Spinoza.456
b) Aristotle, in an effort to pinpoint the nature of sensible
substance in particular, asks whether it is identifiable with
one or more of the following: the universal, the substrate,
the form, and the composite of form and substrate.® Ruling
out completely the Platonist assertion that substance is the
separate universal or idea, he builds to the conclusion that
it is primarily form, hence the cause “in virtue of which
matter is some determinate thing.” Yet the substrate (or
matter) is also given a measure of acceptance. His position,
then, is this, that substance, though substrate, is also and
most of all the formal principle, the determinate essence—
a reminder, this latter, not to overdo the receptive or passive
character of the material subject of accidents.®
c) In the Categories Aristotle enumerates six marks of
substance, which are generally accepted in the Scholastic
tradition. They are:
4 The caution urged by the author is well taken, indeed. In a
maneuver against confusing them, some authors distingush the
perseity of substance from the perseity of God by designating the
latter as a se, which is said of being that exists not only in itself but
also of itself or by reason of itself alone. Being, then, would be
threefold :
1) from another (ab alio)—accidents
2) in itself, by itself (in se, per se)—substance
3) of itself (a se)—God
—Translator’s note.

5 For this discussion, see in particular Metaph. Z & H.
6 Cf. Text VI, “Metaphysics As the Science of Substance,” p. 260.

1Ô2
Philosophy of St. Thomas: Metaphysics
1) “not being in a subject”
2) “to be predicated univocally”
5) “to signify that which is individual”
4) “to have no contrary”
5) “not admitting of more or less”
6) “to be susceptive of contraries” 7
The first of these (“not being in a subject”) does actually
no more than repeat the negative formula for the definition
of substance. The second (“to be predicated univocally”)
applies, of course, to second substance only, which is ex­
plained below under divisions of substance; whereas the
third (“to signify that which is individual”) holds true of
first substance only, also explained below. The fourth (“to
have no contrary”) is true of both first and second substance,
as is the fifth (“not admitting of more or less”). Regarding
the fifth, however, note that it does not mean that one
substance cannot be more truly or less truly substance than
another, but that the same substance is not said to be now
more now less the substance it is—a man (say) is not, at
least metaphysically speaking, more man at one time than
another. As for the sixth (“to be susceptive of contraries”),
this is thought by Aristotle to be the most distinctive mark
of all the true property—the proprium, as the Scholastics
7 Cf. Categories, chap. 5.
Since it may be of interest to some readers (while distracting to
others if run in the text), the properties in Latin are:
1) “non esse in subjecto”
2) “univoce praedicari”
3) “significare hoc aliquid”
4) “non habere contrarium”
5) “non suscipere majus et minus”
6) “esse susceptivus contrariorum”—[Tr.]

The Predicaments
163
have it. No other mode of being admits of successive con­
traries while retaining its identity; the same color, to take an
example, cannot be green, then red, but the same apple can
(assuming the apple to be an individual substance). So much
for the marks of substance, first gathered by Aristotle.
3. Divisions of Substance

a) First substance, second substance. The most noted of
Aristotle’s divisions is that of first and second substance.8
First substance is the concrete individual subject, as “Peter”
or “Socrates.” This is not present in a subject, nor can it be
predicated of a subject. Second substance designates the
universal which expresses the essence of a subject, as “man,”
“horse,” etc. Properly speaking this is not in a subject
either, but unlike first substance it can be predicated of a
subject, as in “Peter is a man,” he has (or partakes of) the
essence of man.9 Based, as is evident, on the predicabilities
of substance, this division serves principally the logician.
For the metaphysician substance is simply the concrete
subject—first substance.
b) Material, immaterial substances. The basic division of
predicamental substance is seen in the first dichotomy of
the Tree of Porphyry, that of material (composite) and im­
material (simple) substances.
Distinctive of material substances is their composition of
8 Cf. Categories, 5, init.
9 If it be wondered at how something can be predicated of an­
other and yet not be present in it, the answer lies in Aristotle’s
meaning, in this context, of “present in a subject”; by this, as he
explains it, is meant “unable to exist apart from that subject.” In
this sense “man” is not present in “Peter,” for Peter is not humanity.
See Categories, 2, 1 a 24.—[Tr.]

i6j.
Philosophy of St. Thomas: Metaphysics
matter and form, complementary principles which, the
human soul excepted, cannot exist apart. That material
substances are ultimately composed of the distinct prin­
ciples matter and form is evidenced, mainly, by the fact of
their generation and corruption, the study of which falls
under the philosophy of nature. From a logical standpoint
they are subdivided according to the specific differences
“living, non-living,” “sentient, nonsentient,” “rational, ir­
rational.”
On a different basis was the ancient division of material
substances by corruptible and incorruptible, a differentia­
tion foreign to modern physics. The ground for the distinc­
tion was not the composition or noncomposition of matter
and form; both admittedly bore this composition. Rather,
the difference lay in the fact that corruptible substances
(sublunary bodies) were subject to all manner of change,
substantial included, whereas incorruptible substances
(celestial bodies) were thought to be under no change but
that of place.
Immaterial substances, on the other hand, are not com­
posed of matter and form. They are known as pure forms,
also spoken of as separate forms; yet this is only by analogy
to material forms and, moreover, should not be taken in
the Platonist sense of subsistent idea. The metaphysical and
psychological (or noetic) investigation of these substances
was not to meet with any real success until the advent of
Christian philosophy, which could build its speculations in
point on the firm foundation provided by the revealed
doctrine of the angels. According to St. Thomas these
substances, among other things, cannot be numerically
multiplied; they lack, as will be seen below, what in

The Predicaments
165
Thomistic thought is the principle of such multiplicability,
matter. Each angel, it follows, is the sole member of (is in
fact) his species; and the totality of angelic species consti­
tues a formal hierarchy, founded on the diversity of essence.
4. Problems Regarding Substance

a) Unity of the substance-accident composite. The dis­
tinction between substance and accidents is a distinction of
reality, not just of the mind. The nearest evidence for the
distinction is that accidents, some of them at least, can
change and even be totally corrupted without inflicting a
change of substance. It can also be urged that some acci­
dents run counter to substance, a circumstance that implies
a real distinction between the two modes of being. Of its
very nature quantity, for example, entails divisibility, where­
as substance works in the opposite direction, making for
unity.
Yet the distinction has been objected to on the ground
that it impairs (if it does not destroy) the unity of the con­
crete being; and if you allow that, it becomes practically
impossible to give a satisfactory account of the changes we
see in things. For, supposing the real distinction, substance
(it is contended) is sealed off from accidents; consequently,
changes that occur must be regarded as coming from ex­
trinsic factors only, surface modifications upon a substrate
the while and forever inert. Substance, then, might still be
the peg on which changes must be hung, though the mod­
erns would soon remove the peg and (they thought) keep
the changes withal.
The foregoing criticism is typical of a wide segment of
modern philosophy. Yet the criticism, to repeat a point

166
Philosophy of St. Thomas: Metaphysics
made earlier, does not hit at substance but at pseudo­
substance. Substance is represented as an inert substrate,
and the real distinction is construed as isolating and in­
sulating substance from accidents, and thus as disrupting
the unity of being. But the truth of the matter is that acci­
dents, while really distinct from substance, are not thereby
prevented from combining with it to constitute a single,
unified being. And if you ask how so, the answer is that
accidents do not have independent existence; they “inhere”
or (if the term be allowed) “inexist” in the subject. It is the
concrete being that exists, a substantial reality that finds
completion in its accidental modalities, all in a unified
whole. So, too, it is the concrete being, the individual, that
changes and acts: the man that thinks, the fire that burns,
etc. Actions, it is a Scholastic axiom, are the supposit’s—
actiones sunt suppositorum. Consequently, it is completely
off the mark to picture substance as one knows not what, an
inert entity concealed behind a cloak of accidents which,
cloak-like, come on and off mechanically. The concrete
individual, the actual existent, though really multiple as to
its principles is yet truly one, and acts as one, doing what­
ever it does from all that it is.
b) Individuation of material substance. Substance (first
substance, obviously) can exist only as individual. Since
there are many individuals, the metaphysician wants to
know what it is that renders them distinct from each other.
In the case of spiritual substances (which are pure forms),
what accounts for their being distinct is their very form or
essence; pure forms, this means, are individuated of them­
selves, of their very nature. Consequently, of such forms or
substances there can only be one for any given nature;

The Predicaments
167
which is to say, each angel is a different species—quot
angeli tot species.
Material substances tell a different story. There we find
not only many species but also many individuals of the
same species, which makes them formally identical. Conse­
quently, not differing in formal or specific perfection, they
must be differentiated or individuated on some other
ground. St. Thomas agrees with Aristotle that the root
principle of this individuation is matter. And why matter?
Because, among other things, the principle that individuates
substantial being must be of the substantial order. The
choice then narrows down to matter or form; not being
form (since material substances do not differ formally), it
must be matter, prime matter. But for matter to perform
this function it needs to be determined by the accident of
quantity; hence the principle of individuation is not matter
pure and simple but, in the accepted phrase, “matter
marked by quantity,” materia signata quantitate.10
St. Thomas explains why the intervention of quantity is
necessary. Form is individuated by being received into this
distinct and determined matter; but matter becomes di­
visible, hence distinguishable, through quantity. Conse­
quently, there is no distinction of material being except
through matter already under dimensions of some kind,
which is matter quantified. However, the quantification in
question, St. Thomas continues, does not entail definite
terminations or determined dimensions of matter, but only
dimensions considered without fixed limits. “From these
interminate dimensions,” he concludes, “results this matter,
signate matter; and as such it individuates form. And thus
10 In Boet. de Trinitate, q. 4, a. 2, resp.

168
Philosophy of St. Thomas: Metaphysics
from matter arises numerical diversity in the same
species.” 11
c) The problem of subsistence. With the mysteries of
faith, of the Incarnation in particular, came a problem about
substance that had escaped philosophers, the vexing prob­
lem of subsistence. But though undiscovered by the philos­
opher, the problem concerns him as well as the theologian.
Subsistence involves the notion of supposit and person.
Supposit, in the present context, means the substantial,
subsistent individual; if the supposit is a rational being, the
designation for it is “person.” The problem, then, is this:
in the existent individual, is there a real distinction between
supposit or person on the one hand and individual nature
or essence on the other? If the distinction is real, there must
be something over and above individual nature, some for­
mality or modal being which accounts for the autonomy
and incommunicability that separate one existent substance
from every other.
Most commentators of St. Thomas, at least since Cajetan, are for the real distinction. Substance, they explain,
needs to be determined or terminated in the order of con­
crete autonomy by a special formality called “subsistence,”
which is conceived as a substantial mode. The mode, or
subsistence, brings it about that a given nature belong to
this individual only and cannot belong to another, (which
is) that it be incommunicable. This additional entity is
thought necessary because without it essence, though capa­
ble of determining and hence limiting existence to a specific
nature, cannot account for the independence, the auton­
omy, that accompanies the existence of the nature. In all,
11 Ibid.

The Predicaments
169
the concrete subject of the created order stands forth as an
individual nature completed by the distinct substantial
mode, subsistence, whereupon ensues the ultimate com­
pletion (or perfection), existence proportionate to the
nature.12

II. ACCIDENTS
a) Meaning of accident. Substance, we have seen, des­
ignates being that exists by itself, (in the sense of) not in
another. Accident, on the other hand, does not exist by
itself; it is, in formal definition, “the mode of being to
which it pertains to exist in another as in a subject of in­
herence”:
res cui competit inesse in alio tamquam in subjecto
inhaesionis.

This point should be stressed, that accident properly
speaking does not exist by itself; it exists only in a subject,13
though it is also true to say that the subject exists through
it. Not that accidents sustain the subject; for the subject
that receives accidents is already a constituted being, a being
12 No problem, it seems, is more recalcitrant to the philosopher’s
(and for that matter to the theologian’s) probe than the problem of
subsistence. For the position, as recently modified, of an eminent
contemporary Thomist see Jacques Maritain, “On the Notion of
Subsistence,” in Progress in Philosophy, pp. 29-45 (f°r publisher,
etc. see chapter 2, note 7). This article of Maritain’s is excerpted
from The Three Degrees of Knowledge, newly translated from the
fourth French Edition under the supervision of Gerald B. Phelan
(New York: Charles Scribner’s Sons, 1959), pp. 434-444 (Appendix
IV).—[Tr.]
13 Tire theologian, to be sure, knows of an exception, the Eu­
charistic Species (accidents); but this transcends the order of nature.
-[Tr.]

iyo
Philosophy of St. Thomas: Metaphysics
in (first) act. Nevertheless the constituted subject is in
potency as regards the perfection which the accidental form
is to confer upon it; and in this sense the subject exists (in
second act) through the accident. Also, it is perhaps not
superfluous to warn that the accident of which we now
speak, the predicamental accident, should be scrupulously
differentiated from accident considered as one of the five
predicables, which refer to modes of predication.
b) Schematic presentation of the accidents. Aristotle, it
appears, arrived at his collection of nine accidents by em­
pirical test. They can, however, as we find St. Thomas do­
ing, be derived on a more systematic basis, according as
they determine the subject intrinsically, or extrinsically, or
partly both.14 The following passage details the procedure,
the first paragraph (which pertains to substance) serving as
introduction:
A predicate can be referred to a subject in three ways. This
occurs in one way when the predicate states what the subject
is, as when I say that Socrates is an animal; for Socrates is the
thing which is an animal. And this predicate is said to signify
first substance, i.e. a particular substance, of which all attributes
are predicated.
A predicate is referred to a subject in a second way when
the predicate is taken as being in the subject, and this predicate
is in the subject either essentially and absolutely and as some­
thing flowing from its matter, and then it is quantity; or as
something flowing from its form, and then it is quality; or it is
not present in the subject absolutely but with reference to some­
thing else, and then it is relation.
A predicate is referred to a subject in a third way when the
14 Cf. In III Phys. lect. 5; In V Metaph. lect. 9.

The Predicaments
171
predicate is taken from something extrinsic to the subject, and
this occurs in two ways. In one way, that from which the predi­
cate is taken is totally extrinsic to the subject; and if this is not
a measure of the subject, it is predicated after the manner of
attire [possession], as when it is said that Socrates is shod or
clothed. But if it is a measure of the subject, then, since an
extrinsic measure is either time or place, the predicament is
taken either in reference to time, and so it will be when; or if
it is taken in reference to place and the order of parts in place is
not considered, it will be where; but if this order is considered,
it will be position.
In another way, that from which the predicate is taken,
though outside the subject, is nevertheless from a certain point
of view in the subject of which it is predicated. And if it is from
the viewpoint of the principle, then it is predicated as an action;
for the principle of action is in the subject. But if it is from the
viewpoint of its terminus, then it will be predicated as a passion;
for a passion is terminated in the subject which is being acted
upon.15

Casting a critical eye over this table of accidents, we
should find that two of them (possession, position) do not
command as much interest or importance as the others,
for all that they must be acknowledged to represent really
distinct modes of being and predication. Possession
(habitus) names an accident so extrinsic to a being that it
is itself a substance or an aggregate of them, for example a
garment; moreover, it is properly said of only one particular
kind of subject, man. As for position (situs), this, to be
sure, is not the same as place, for it tells, as place does not,
the order of parts relative to each other; but it is clearly a
15 In V Metaph. lect. 9, nos. 891-892.

172

Philosophy of St. Thomas: Metaphysics

This passage can be reduced as follows:
T) the subject....................

substance

Predica­
-perse
Ffollowing on matter.. .quantity
ment re­
fers to
< 2) or in and ab- <
the J solutely ^following on form......... quality
that
sub- <
which is
ject not ab­
solutely.......................................... relation
"yet
.action
some as principle
way
3) or
passion
as terminus
out- in it
side
” and not a
the <
possession
sub­ or en­ measure of it
ject
tirely
when
’as to time
out- < ora
_ side it meas­
'but not
ure
its parts.. .where
as to
_of it
place and its
parts.,. .position

The Predicaments
173
derivative predicament and so, like possession (though this
is not derivative), of less significance than place or the other
predicaments. Aristotle’s mind appears to be in line with
what we are saying, for he does not always include pos­
session and position in his naming of accidental being.
Again, in its totality the predicamental system applies to
material substance only, a point made earlier. Only this sub­
stance is quantified; it alone (one kind of it) can have ex­
ternal possessions; and it alone is subject to the conditions
of space and time and to the circumstances of transeunt
action. This is to say that the study of most of the predica­
mental accidents is properly remanded to the philosophy of
nature; namely, the treatment of quantity, possession, place,
time, position, action, and passion. This leaves substance,
quality, and relation. Of substance we have spoken. Of
quality and relation we have now to speak; for these, en­
countered as they are in immaterial as well as in material
being, are more definitely the concern of metaphysics.

1. Quality
Aristotle’s principal exposition of the doctrine on quality
appears in the Categories.16 A secondary treatment occurs
in the Metaphysics.1’’ In both instances he follows his
custom of empirical analysis, identifying and classifying the
more prominent modes of being which could come under
this category. The more logically conceived presentation of
the topic, the standardized version as it were, we owe to his
commentators, and notably to St. Thomas.
a) Nature of quality. The supreme genera of being can16 Cf. Categories, chap. 8.
17 Cf. Metaph. A, 14.

174
Philosophy of St. Thomas: Metaphysics
not, strictly, be defined. They are irreducible modes, and the
notions corresponding to them will be similarly irreducible.
What is possible is to advance from an indistinct grasp of
such notions to a more clear-cut one. In the case of quality,
Aristotle looks for this clearer understanding of it in the
effects produced by the predicament, which, though varied,
are yet somehow one; for the effect of quality is always to
render a thing “such and such.” That, as a matter of fact,
is how Aristotle first introduces quality, as the predicament
by reason of which things are said to be “such and such,”
i.e. “qualified.” In Scholastic phrase:
qualitas est secundum quam res quales dicuntur.

Doubtless, the first “qualification” of a subject comes
from its substantial form, which causes a thing to be specifi­
cally distinct from other things. But this first qualification
or determination alone does not suffice for the entire per­
fection of a being. Required, in addition, are those super­
venient qualifications belonging to the order of accidents;
hence the qualities issuing in these additional qualifications
will come under a predicament of their own.
But how does quality itself differentiate from the other
predicamental accidents? Simply by introducing something
into the subject which is not introduced by the others. For,
while all accidents do in a way determine the subject, all
do not “qualify” it, do not cause it to be “such and such”
intrinsically and formally. Quantity, say, causes the material
subject to be divisible, and its parts to be extended; but this,
obviously, is not the same as to “qualify” it. Quantity and
quality are therefore really distinct. As for the other acci­
dents, if in some way they can be said to qualify the subject,

The Predicaments
175
it is only from the outside, as it were, or in reference to some­
thing other than the subject. So that to “qualify” the sub­
stantial subject, in itself and intrinsically, can only be the
effect of quality in the strict sense, such as color or those
dispositions of body and soul which are named virtues.
Consequently, there is ample ground for accounting quality
a separate predicament.
b) The species of quality. Aristotle distinguishes four
species of quality,18 which St. Thomas reorganizes under a
threefold classification.19 As given by Aristotle they are:
1st species: habit and disposition
2nd species : capacity and incapacity
3rd species: affections and affective qualities
4th species: form and figure
Habit and disposition determine the substantial subject
in regard to its nature, and are said to be good or bad ac­
cording as they are, or are not, directed to the perfection of
the nature in question. Habit, moreover, differs from dispo­
sition as the stable from the unstable; habit, accordingly, is
more lasting, more firmly established. Examples of habit:
intellectual virtues (science, prudence, art), moral virtues,
manual skills.
Affecting the subject as to its activity are the qualities
capacity and incapacity (potentia, impotentia). Capacity
disposes the subject to receive or give resistance to an ac­
tivity; thus, intellect, imagination, will (others could be
mentioned) are capacities through which the subject re­
ceives (exercises) the activities of these faculties. If the ca­
pacity is undermined or weakened, it is called “incapacity,”
18 Categories, loc cit.
19 Cf. Summa theol. la Ilae, q. 49, a. 2.

176
Philosophy of St. Thomas: Metaphysics
which, then, does not mean the total absence of a power or
faculty. Enfeebled vision would in this sense be an inca­
pacity, but not so total blindness; or (Aristotle’s example),
some men are healthy because of the capacity to resist un­
healthy influences, others unhealthy because of a lack of
this capacity,—but not a complete lack, which spells death.
Affections and affective qualities (passiones, passibiles
qualitates) are qualities which produce, or are produced by,
sensible alteration; that is, qualities from which alteration
begins and in which it terminates. In general, they affect
the senses immediately, and include the sensible qualities
of bodies and the bodily temperaments and passions (feel­
ings and emotions). Within the third species a distinction
is made on the same basis as in the first species, relative
permanence and impermanence. If the quality is lasting, it
is one of the “affective qualities”; if quickly passing, it is an
“affection”—example, the blushing complexion versus the
blush of modesty. Among the basic qualities of the third
species, in Aristotelian thought, are hot, cold, dry, wet, and
mixings of them.
Finally, with respect to continuous quantity the distinc­
tion of form and figure is made, which proportion and ter­
minate it, since it must be terminated or limited. Form
adds to figure the note of due proportion and refers, in a
special sense, to works of art. Thus, we speak of a spherical
figure, but of the form (or shape) of a vase.
As indicated some paragraphs back, quality in the wider
sense may also mean a mode or determination of substance,
its specific difference. Bearing this in mind, we can (with
St. Thomas) adopt the following arrangement of the fore­
going matter:

The Predicaments

J77

according to substantial being=specific difference of the
substance
"in regard to
Quality,
the nature
a mode
of
the subject=habit or disposition
or deter­
(ist species)
mination
according
action=capacity & incapacity
of the
in re- /
(2nd species)
to acci­
subject
gardZ
dental
to ^passion=affection & affective
_being
quality (3rd species)
in regard to quantity=form & figure
(4th species)

2. Relation

It is evident that created things, each and all of them,
are variously related to one another, by equality, by simi­
larity, by causality, etc. There is a type of relation, however,
which is more difficult to grasp, though it is quite real, the
transcendental relation. This is not our immediate concern,
but should nevertheless be sufficiently noted to distinguish
it from the relation of which we do have here to speak, the
predicamental:20
Transcendental relation is an order according to which a
thing is of its very nature referred to another; for example,
the relation of the will to good, of the intellect to being,
and more generally, of potency to act. This relation is not
really distinct from the essence of the thing concerned, but
20 Transcendental and predicamental relation are also known re­
spectively as secundum dici and secundum esse, which, as the author
explains, means relation as pertaining to the very definition of an
essence and relation as a distinct mode of being and therefore with
a nature of its own.—[Tr.]

178
Philosophy of St. Thomas: Metaphysics
expresses the essence itself in its reference to another. In
short, it enters into the very nature of a thing and thus
forms part of its definition. By contrast, the predicamental
relation has its own reality, distinct from the subject which
is referred or related. Hence it does not enter into the defi­
nition of the subject but has a nature of its own.21
a) Nature of predicamental relation. Predicamental rela­
tion is defined as an accident whose entire being consists
in its reference to another:

accidens cujus totum esse est ad aliud se habere.
The whole essential, then, of this relation is a respect to
something else, a “towardness” of some kind. But before
the relation can arise certain things, it should be obvious,
are required: 1) a subject, that which is related or referred;
2) a term, that to which the subject is referred; and 3) a
foundation, the reason or aspect under which the subject is
referred to the term. For instance, this man (subject) is sim­
ilar, or is related by similarity to that other man (term)
because of his, the subject’s, white hair. Of course, the sub­
ject is in one sense a term, too, so that we may speak of the
two terms or two extremes of the relation.
There are, however, difficulties attending upon the nature
of predicamental relation, which have led some to deny its
existence altogether. The predicamental relation is sup­
posedly a real accident; yet all its being is comprised in the
reference to another, in something which, as it were, hangs
suspended outside the subject. How, then, can it still be in
21 For Aristotle’s discussion of “relatives” see Categories, chap. 7;
Metaph. Á, 15.

The Predicaments
179
the subject, an accident of it, when its very essence consists
in pointing to something outside, in the reference itself?
Doubtless (we reply) the nature, the proper essential of the
relation is reference or “towardness”; nevertheless, the rela­
tion cannot support itself, it must have a footing, a flooring,
something that receives it. This is the subject, of which it
is accordingly an accident, as (say) paternity is something
real, but an accidental reality, for a man.
Another (and perhaps deeper) question is whether the
relation is really distinct from its foundation. And more
generally, if things are already related to each other tran­
scendentally, why superimpose upon them a whole new
order of relational entities, the predicamental relations?
The answer (to the second question) is that these relations
are demanded by the facts of experience; to be related to
another constitutes a mode of being, hence a distinct pre­
dicament. A clear indication that these relations have an
ontological status of their own is seen in the fact that a
relation can appear or disappear without its term under­
going any modification in itself. As for the distinction be­
tween relation and its foundation, St. Thomas insists it is
real; for, among other things, the distinction again meets
the test of separability—indeed, the two questions (why
relations at all, and what the distinction of relation and
foundation?) come to one. Two white objects, for example,
are related by similarity. If one object is destroyed, the rela­
tion ceases; yet the whiteness, its foundation, survives in the
still existing object. But surely, what is really separable is
really distinct.
b) Division of predicamental relation. A relation is either

i8o
Philosophy of St. Thomas: Metaphysics
real or logical (relation of reason): real, if it exists inde­
pendently of the mind, as the relation of father to son;
logical, if it depends upon the consideration of the mind, as
the relation between subject and predicate of a proposition.
Predicamental relation is of course real; it meets the requis­
ites of a real relation, which are: i) a real subject, 2) a real
term, 3) a real distinction between them, yet so as to be
referable one to the other, and 4) a real foundation.
Essentially, predicamental relation is divided according
to its foundation. If this denotes that one thing depends in
some way upon another for its existence, we have a relation
of causality (not to be confused with the exercise of causal­
ity); otherwise, when no such dependence is involved, the
relation is one of mere agreement or disagreement, the
nature of which varies with the foundation. With sub­
stance as foundation the relation is one of identity or di­
versity; with quantity, one of equality or inequality; with
quality, one of similarity or dissimilarity.
The accidental division is that of mutual and nonmutual.
A mutual relation is bilateral, that is, bilaterally real: to
the real relation of subject to term corresponds a real rela­
tion of term to subject, as father to son and inversely. The
nonmutual relation is unilateral, real from one side, logical
from the other. In knowledge, for example, there is a real
relation of intellect to thing known, for the intellect depends
upon the thing for its knowledge; but the relation of thing
to the speculative intellect is only a relation of reason (or
logical), because the thing is in no way affected simply by
being known. Again, the relation is real from creature to
Creator, but not real in reverse order, from Creator to
creature.

The Predicaments
All of which, in conspectus, reads thus:

181

logical
Relation

'transcendental
.real

predicamental
"regarding dependence of existence
foundation
mutual
or
action & passion: causality
nonmutual
not regarding dependence of existence
foundation
substance: identity-diversity
quantity : equality-inequality
quality : similarity­
dissimilarity

t CHAPTER 6

Acl and Potency

i. Genesis of the Doctrine of Act and Potency

t THE distinction of being into act and potency was
first enunciated by Aristotle, and while he may not have
unveiled every development which this doctrine invites, no
one questions that he established the essentials. St. Thomas
had only to pursue the line of thought marked out by Aris­
totle, and the doctrine would attain fulfillment.1
It is in the Physics, when searching for the principles
that would account for change, that Aristotle seems first to
have employed the notions of act and potency. Already in
the first Book the co-principles of matter and form are
distinguished as act (form) and potency (matter). The dis­
tinction is subsequently invoked as the key to the under­
standing of motion, which is defined in these very terms
as the act of what is in potency as such, that is, so far as it
is in potency. Finally, after various other applications of
the notions, the work culminates in the prime mover, pure
act in which all motion of the universe is resolved.
1 Cf. St. Thomas, In IX Metaph., with special reference to lectt.
i, 5, J, 8, 9.

184
Philosophy of St. Thomas: Metaphysics
In the Metaphysics act and potency reappear to consti­
tute, with the predicaments, the first divisions of being.
The whole of Book ® is given to act and potency, a book
in which there begins to emerge Aristotle’s concern to bring
them to bear, not just an motion as such, but on a far
wider range of reality, and indeed on all reality, that of
pure form and immovable act included. What he does, in
effect, is to lay the groundwork for the theological specula­
tions of Book A, in which the primary substance is ex­
pounded under its proper characteristic, its pure actuality.
However, Aristotle’s utilization of act and potency is not
confined to strict metaphysics; rather, the doctrine is pressed
into service throughout his works. In psychology he is con­
stantly having recourse to these two principles, and finds
applications for them in logic and even in mathematics.
Hence, it is really not to be wondered at that act and
potency should be regarded by some as the cornerstone of
his entire philosophy. But whether this be so or not, the
central importance of the doctrine is clear enough.
As for its origin, that, as already intimated, traces to the
problem of change. Aristotle’s solution is traditionally, and
quite properly, taken as middle to the extremes represented
by Parmenides and Heraclitus. Between being and nonbeing
Parmenides could find no alternative; the result was to
deny the reality of change or becoming. His reasoning in
point is simple, and decisive (granted his premise). Being,
he protested, cannot come from being which already is; in
other words, what is cannot become (what it already is).
Nor can it come from nonbeing, which, in his view, must
be nothing. And that is of course true; where there is
nothing, nothing can emerge. Consequently, if being can­
not come from being nor from nonbeing, it cannot come,

Act and Potency
185
or become, at all. Result: there is no becoming, there is
only being.
To this extreme the traditional Heraclitus opposes an­
other, that change is not only real but (to all indications)
the only reality; for, behind the incessant flow of appear­
ances no abiding principle or reality is to be found. Hence
all is becoming, and being as such does not exist. But if
being is denied and only becoming affirmed, even becoming
would seem to be ruled out; for what possible meaning is
there to a becoming that does not become something,
some being? 2
The problem, then, is one of salvaging both being and
becoming. The distinction of act and potency points the
way—the way out of the Parmenidean dilemma. We have
simply to recognize a kind of intermediate state between
being as fully determined, which is being in act, and nonbeing considered as pure nothing. This intermediate state
is being in potency, which is real though not yet perfectly
realized. Change, accordingly, becomes possible and is ex­
plained as a transition from being in potency to being in
act.3 Suppose (to illustrate) that a sculptor decides on a
2 However, the traditional Heraclitus may not be the real one, a
closer reading of the sources suggesting that this pre-Socratic was not
the complete Phenomenalist he is much made out to have been.
See, for example, R. K. Hack, God in Greek Philosophy, chapter 7
(Princeton: Princeton University Press, 1931); or, for summary,
Herman Reith, C.S.C., “The Marxists Interpret the Pre-Socratics,”
The New Scholasticism, 27, 4 (Oct. 1953), pp. 408-413.—[Tr.]
3 Objection has been raised, in this connection, to referring to
change (or motion) as a passage or transition (cf. Vincent E. Smith,
The General Science of Nature [Milwaukee: The Bruce Publishing
Company, 1958], p. 257). While Dr. Smith is doubtless correct in
remarking that transition or passage is itself a case of motion, hence
should not be used in its strict definition, there would seem to be

186
Philosophy of St. Thomas: Metaphysics
statue. Selecting a block of marble he carves it down to his
subject. Metaphysically speaking, what has taken place?
When the statue is finished, it exists in act. But where was
it before the sculptor put chisel to marble? Clearly, it did
not exist in act, but did it exist in any way at all? If you say:
no, it had no reality whatever, then the fabrication of the
statue becomes unintelligible, inexplicable—an emergence
from absolute nothing, which is absurd on the face of it. In
truth, the sculptor could not apply himself unless there was
at his disposal a suitable material, the marble, from which
he extracted, as it were, the statue. To repeat, the statue did
not exist in act in the naked marble, but it could be hewn
because it was there in potency. In the fabrication it went
from a statue in potency to a statue in act.
What is true in art is analogously true in nature, in the
germination and growth (say) of a seed. The plant that has
reached full development did not exist in act in the seed;
yet exist in the seed it did, but in potency. We may gen­
eralize these examples and apply their particulars to all like
cases. Change, every change, we shall find, is a going from
being in potency to being in act. With that, both realities
are safeguarded, the reality of becoming as well as of being.
Thus what was (to some) the insoluble problem of change
is resolved by the distinction of act and potency. These
rudiments in hand, we have now to examine each member
of the distinction more closely.*
4
no harm in using these terms merely to indicate that in motion (or
change generally) tire state of potency is followed by the state of im­
perfect act and, at its termination, by the so-called state of perfect
act.—[Tr.]
4 Cf. Text VII, “Potency and Act,” p. 263.

Act and Potency

187

2. Potency

a) Meaning of potency. Potency belongs to those primary
analogous notions that cannot be defined, in the proper
sense of the word. We have therefore to proceed as it were
inductively, by examples, and by comparing one notion
against its opposite, since what a thing is, is often conveyed
by what it is not.
A first differentiation to be made is between potency and
its cognate, possibility. Like being in potency, possibility
denotes relation to existence; it can exist. But it does not yet
exist in reality, it exists only in the mind of the one con­
ceiving it, ultimately and basically in the mind of God.
Because the possible as such exists only as an object of
thought it is called objective potency; whereas potency in
the proper sense, the sense spoken of here, is named sub­
jective, meaning 1) it exists in a real subject, and 2) it is
something real in the subject (having real, as opposed to
conceptual, being).5
The mere possible, it follows, is simply that which does
not involve contradiction; not yet real, it can be realized, at
least by the power of God. By contrast, potency (or being
in potency) belongs, as we have said, to the order of reality,
as that ingredient of it which determines its further realiza­
tions—or better, actualizations. However, to be in reality is
not necessarily to be in act; this is a crucial point, and it
escaped Parmenides. Potency is real, a real mode of the
5 Attention might well be called to the special meaning of “objec­
tive” and “subjective” in this context, for in more popular parlance
the objective order is precisely the order of reality and the subjective
order the realm of the mind.—[Tr.]

188
Philosophy of St. Thomas: Metaphysics
subject, but it is not actual; indeed, potency as such is never
in act, though what is in potency in one respect may be in
act in another. It is fruitless, however, to seek a graphic
image of a reality of this kind; the imagination does not
portray it, but the intellect conceives it. Nor should the
potential be equated with the implicit; the implicit may
well be actual, never so the potential.6
But all this is a negative analysis of potency; and since no
reality is all negation, a more positive conception is wanted.
But how go about finding it? Simply by recourse to partic­
ular instances, to concrete examples, which will supply the
analogies from which the positive concept can be formed.
The case of the statue will do. The statue is in the marble
that has not been carved, but it is there in potency. Or,
another instance, thought is in the intellect that is not
thinking, but it is there in potency. Now, whatever the in­
stance, we find one thing common to the state of potency,
namely relation to act. Potency always expresses relation to
act: potentia dicitur ad actum. This is the quintessence of
potency, its truest essential. Going a step further, we can
say that potency is related to act as the state of imperfection
to the state of perfection or completion. The finished statue
is the statue in the state of perfection; in the uncarved
marble it was in the state of imperfection. Where there is
potency, there is imperfection, of necessity. Two things, ac­
cordingly, characterize every potency: relation to act, and
imperfection. Whatever else be said of potency, nothing
does it better than these.
6 It should perhaps be added that another way of distinguishing
the mere possible from potency proper is to designate the former
as logical potency and the latter as real potency.—[Tr.]

Act and Potency
189
b) Division of potency.7 Aristotle, as is his way in such
matters, first sets out what he considers to be the basic kind
of potency, the one in reference to which other potencies
are named. This is the potency called active, the power to
effect a change in another as other. Corresponding to this
is the potency named passive, the capacity a thing has to be
changed by another as other. Aristotle further distinguishes
the rational and the nonrational potencies. Disregarded al­
together, however, are those which are potencies only by
equivocation, as occurs (say) in geometry, where one thing
is said to be, or not to be, a “power” of another, depending
on their relation or nonrelation. On the whole, then, po­
tencies can be catalogued as follows (which includes some
important additions of Scholastic origin):

Potency in the proper sense is the kind called subjective,
which is divided against the mere possible, or objective
potency.
Subjective potency is subdivided into active potency, the
principle of activity in an agent,8 and passive potency, the
capacity of a thing to be changed by another.9
Considered in reference to the agent passive potency,
moreover, is either natural or obediential: natural if the
reference is to an agent immediately proportioned to it,
obediential if it must be referred to a transcendent agent,
specifically to the agency of God.
In regard to its act passive potency is further differenti7 Cf. Metaph. ®, 1-2.
8 Latin : principium transmutationis in aliud in quantum est aliud.
9 Latin : principium quod aliquis moveatur ab alio in quantum
aliud.

iço
Philosophy of St. Thomas: Metaphysics
ated according as it relates to essential act (substantial and
accidental form) or to existential act, the act that is exist­
ence.
Active potency, for its part, is created or uncreated; if
created it pertains either to the order of immanent action,
thus the rational potencies, or to action which is essentially
transeunt, the case of nonrational potencies.
All which, in sketch, is this:

Objective: the pure possible, also called logical
Potency

.uncreated (minus all potentiality)

Active'

rational
•nonrational

Subjective: potency proper, also called real
natural
relative to agent
obediential
Passive.
first matter
essential act\

second matter
relative to.

'existential act=essence

Act and Potency
3. Act

a) Meaning of act. Act, like potency, is a primary notion
which can only be grasped through example and illustra­
tion. Aristotle takes note of this circumstance; “we must
not,” he cautions, “look for a definition of everything but
be satisfied to grasp the analogy, that it [act] is as what
builds is to what is capable of building; as waking to sleep­
ing; as what is seeing to what has eyes shut but has sight;
as what has been fashioned out of matter to the matter; as
what has been wrought to what is unwrought. Let act stand
for the first member of these opposites, and potency for the
other.” 10 St. Thomas, in the wake of Aristotle, puts all this
to summary when he says, “Act is when a thing is, but is
not as in potency.” 11
Thus, one reveals the other. Potency is characterized and
expressed by relation to act; act, in turn, is manifested
through contrast with potency. Nevertheless, there is a
notable difference; for, while act is included in the very
notion of potency (dicitur ad actum'), the converse is not
true, act does not necessarily imply potency. The first mean­
ing of act is completed being, which may be only relatively
complete. However, we do know of a pure act which is rela­
tive to nothing. Act, in short, is prior to potency, hence not
necessarily attended by a potency. More about this as the
chapter progresses. For now, suffice it that the positive
meaning of act is completed being, which is to say perfec10 Metaph. ®, 6, 1048 a 36-1048 b 5;
11 “Actus est quando res est, non tamen est sicut in potentia” (cf.
In IX Metaph. lect. 5, no. 1825; Aristotle, Metaph. ®, 6, 1048 a 31).

1Ç2
Philosophy of St. Thomas: Metaphysics
tion, whereas potency always conveys the opposite, imper­
fection.
b) Division of act. Aristotle, after elucidating the notion
of act by citing concrete instances, calls attention to its
being analogous and, without further ado, distinguishes the
two typical varieties; act, he says in effect, is in one sense as
movement to potency, in another as substance (i.e. form)
to some kind of matter.12 This, more simply, is the dis­
tinction between operative and entitative act, or act as
operation and under its static aspect.13 And since we are
dealing with an analogous concept, one of these, the opera­
tive act, may be taken as the primary analogate, whence is
derived the notion of the other.
Equally well established are a number of other distinc­
tions, and first of all, that of pure and mixed act. Pure
or unreceived act is void of all potency and is not received
into a potency.14 Mixed act, as the name implies, admits of
potency, hence is any act that enters into composition with
potency. Mixed act, moreover, can be divided according as
it pertains to form or to operation.
In the static order (spoken of above) mixed act may refer
12 Metaph. ®, 6, 1048 b 8.
13 The author, here, apparently parts company with the more
usual terminology, for entitative act is perhaps better said of esse
than of essence (substance or form, it should not be forgotten, being
of the essential order).—[Tr.]
14 In a being where essence and existence are distinct pure act can
only be said, if at all, of its essence, for such a being is obviously not
pure act or unlimited in every respect; the case in point is, of course,
the angelic essence. But where, as in the unique case of God, essence
and existence are identical, the pure act of essence is the pure act of
existence; needless to say, this is the meaning of pure act in the
unqualified sense—[Tr.]

Act and Potency
193
to the essence, hence essential act, or to existence, existen­
tial act.
In the dynamic order (operation) occurs the distinction
of spiritual activity, or immanent act, and physical activity,
transeunt act.
In skeleton, the distinctions are:

Pure: unreceived
.substantial form
,essential^
'accidental form

Ac

In the order of beinj
(static order)
istential=existence (esse)
Mixed

immanent action

In the order of operation

transeunt action
4. Concerning the Relation of Act and Potency

a) Priority of act to potency. Act and potency are correla­
tives but there is nevertheless a definite order, a sequence
as it were, between them. Act is prior; act accounts for
potency, but potency does not account for act as such. In
Aristotle’s analysis this priority is shown to obtain in sev­
eral respects.15
First, act is prior in concept or definition; for potency is
defined by act, that is, in relation to act, as the ability to
build is known from the act of building.
Second, in the order of time a distinction applies. The
individual is in potency before being in act; the acorn pre­
cedes the oak, the imperfect the perfect. But from the larger
15 Cf. Metaph. ®, 8.

194
Philosophy of St. Thomas: Metaphysics
point of view of the species the perfect state, which is act,
precedes the imperfect state, which is potency. The poten­
tially existent must always come from the actually existent,
man from man, etc.
Third, according to substance (or perfection) act again
is first, mainly because, in Aristotle’s words, “everything that
comes to be moves toward its principle and end; for the
principle is the final cause, and the becoming is for the sake
of the end, but the end is the actuality.” 16 In short, the
priority of act stems in this case from the priority of final
cause, which has obviously to be act.
Lastly, Aristotle interposes an argument that marks a
notable advance in his metaphysics as a whole. Eternal
beings, he submits (without warning or discussion), are prior
to corruptible ones. Then to the point at issue: that eternal
beings have no potency to nonbeing, hence are not in
potency; which is to say there are beings in act that are
prior to all potency. This argument, it may be noted, does
more than substantiate the priority of act; it anticipates
the pure act, the burden of the subsequent Book A.
b) Every activity has its principle in act. Every activity
must proceed from a being in act with respect to the aim
and scope of the activity.17 This proposition, which is axio­
matic in the Aristotelian tradition, follows from the general
priority of act spoken of above. The equivalent thought
emerges from another Scholastic axiom, that what is in
potency cannot be reduced to act unless by a being in act.18
18 Ibid. 1050 a 6-9.
17 As the Scholastic Latin has it: “nihil agit nisi secundum quod
est actu.”
18 Latin: “quod est in potentia non reducitur in actum nisi per
ens actu.”

Act and Potency
195
Potency, this means, cannot be raised to the level of act by
itself; only a being already in act, exercising efficient causal­
ity, can bring this about. Yet, though necessarily in act, the
agent must also have the potency to act. Is not this a contra­
diction? No, it is quite possible to be in act and potency at
the same time, but not in the same respect. In a created
agent act and potency are complementary. For the exercise
of efficient causality the agent must be in act through posses­
sion of the form (or perfection) which is to be produced in
another; and must at the same time be in (active) potency
as regards the action to be performed. So, for instance,
the intellect when actuated (or in act) by the impressed
species, is in (active) potency as regards the act of in­
tellection.
c) Limitation of act by potency. We have now, following
Aristotle, set out the distinction of act and potency, defined
the one and the other, noted their principal divisions, and
established the priority of act. When we turn to St. Thomas
the doctrine of act and potency receives, if anything, even
more attention than it does in Aristotle; and certainly, it is
put to far greater use. In fact, St. Thomas and not a few
Scholastics regard the distinction of act and potency as in
some sense, the key principle of metaphysical thought, the
answer (or at least, an answer) to the riddle of being. Finite
being is explained, basically, as a composition of act and
potency; and since infinite being is grasped by us only
through the medium of finite being, even theology rests on
the doctrine of this distinction.
To say “finite” is, moreover, to say “limited.” This brings
up the metaphysical question of the limitation of being; or,
what is it that limits a being intrinsically? St Thomas and
his followers answer in unison: act can only be limited by

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Philosophy of St. Thomas: Metaphysics
potency.19 Thus, in the composition of act and potency act
is related to potency as the limited to the limiting.
In proof of this we have the following. Of itself act means
perfection. If, then, we find a perfection limited there must
be a reason for the limitation. The reason, however, cannot
be in the perfection itself; for if perfection is limited by
itself then perfection is by nature imperfection, an obvious
contradiction. Consequently perfection, if limited, is lim­
ited by a principle distinct from yet united with it; this
principle is potency. Thus, in every composition of act and
potency, act is limited by potency. The corollary to this is
that pure act is absolutely unlimited, hence absolutely per­
fect. This line of reasoning, no doubt, is correct; but St.
Thomas, while convinced of the conclusion, comes to it
from what would seem to be a more organic and more
realistic approach, namely, from the over-all consideration
of participated and unparticipated being.
The opposing view held by Scotists and Suarezians should
at least be mentioned, that act can be limited in itself. All
that is required, then, for the limitation of act is that the
extrinsic or efficient cause, ultimately God, should consti­
tute it in this degree of being instead of that. Perhaps, in
comment, this view suffers from a lack of attention to the
distinction between intrinsic and extrinsic principle of
limitation.
d) Multiplication of act by potency. If potency is the
(intrinsic) principle of limitation, it is also, and for that
19 As the Sacred Congregation of Studies phrases it: “actus, utpote
perfectio, non limitatur nisi per potentiam, quae est capacitas per­
fectionis.” For a complete statement of this second of the Con­
gregation’s 24 Thomistic theses, see below, p. 199.

Act and Potency
197
very reason, the principle of multiplication. Suppose an act
that is not limited by potency; such an act is unlimited or
perfect, and therefore unique.20 Unique, because if two
beings were equally (and infinitely) perfect, one could not
differ from the other; in fact, they would cancel each other.
Wherever, then, perfection is plural, the perfection must be
limited. But we know it is not limited by itself, hence by
something not itself; and this, as we have learned, is po­
tency, which limits act (or perfection) by receiving it and
thus makes possible its plurification.
e) Reality of the distinction between act and potency.
Scotists and Suarezians maintain that the distinction be­
tween act and potency is only “formal,” that is, logical, but
with a foundation in the things considered (rationis ra­
tiocinatae'). For Thomists, however, the distinction is
real; and for St. Thomas in particular there could hardly be
any question about the matter. The reality of it is generally
argued this way. Potency denotes capacity for perfection,,
whereas act of its very nature signifies perfection; such
opposite notions must correspond to entities that are really
distinct.
More authentic, perhaps, from the Thomistic stand
would be the argument that act, because its reception into
potency is by way of causality or participation, must be
really distinct from the receiving potency. The distinction,
for that matter, is also evidenced experientially, or a pos­
teriori; for sometimes we observe that a potency is without
the act it previously had—the sense (potency) of sight, for
20 Which, incidentally, is why St. Thomas holds for the unicity of
every angelic essence, since this essence, as essence, is not a com­
posite of act and potency but pure act (or form).—[Tr.]

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Philosophy of St. Thomas: Metaphysics
instance, is not always in the act of seeing. Possibly the
Scotist and Suarezian trouble with the real distinction stems
from a too literal or too coarse interpretation of it. The
composition of act and potency is not a union of two
complete beings each of which could exist separately. We
have said it before, a real distinction does not necessarily
mean that the things in question can exist apart, though
what is separable is certainly distinct. Act and potency are
not two beings but two principles of being which determine
each other but which, while really distinct, do not have
each a distinct existence.
5. Conclusion: Act and Potency as the Cardinal

Principles of Thomistic Metaphysics

First propounded in explanation and defense of the real­
ity of motion, the doctrine of act and potency was destined
for far wider application. It was in due course found to be
relevant to the structure and the incident limitation and
multiplicity of created being, as well as, in contrast, to the
simplicity and infinity and unicity of God. Its utilization in
these areas enlarged its scope immeasurably. It may be fairly
said that the focal distinctions of matter and form, of sub­
stance and accident, yes of essence and existence are but
applications, significant ones at that, of the still more
pivotal distinction of act and potency. Here, then, it is
commonly said, is a cardinal conception, the heart and
focus of Thomistic metaphysics.
This appraisal is to the mark; there is scarcely a meta­
physical problem to which the doctrine of act and potency
does not lend some manner of solution, and exploring its
possibilities has proved fruitful indeed. For all that, how­

Act and Potency
199
ever, it would be a fatal illusion to imagine that once the
essentials of the doctrine with its real distinction have been
set forth, the machinery of logical deduction has only to be
put in gear and all the central theses of metaphysics are
automatically delivered. The distinctions mentioned above
(matter and form, etc.) are original as well as comparable
or similar to that of act and potency, and bringing them
into line with the latter is in every instance a problem of its
own, the solution coming not mechanically but through
hard-won insight. We mention this, not to depreciate act
and potency, but to caution against their oversimplication.
Having made the point, we append, by way of recapitula­
tion, the first two Thomistic theses proposed by the Sacred
Congregation of Studies, veritable epitomes of the doctrine
of act and potency:
Thesis I: Potency and act so divide being that whatever
exists is either pure act, or is necessarily com­
posed of potency and act as its first intrinsic
principles.
(Potentia et actus ita dividunt ens, ut quidquid
est vel sit actus purus, vel ex potentia et actu
tamquam primis atque intrinsecis principiis
necessario coalescat.)
Thesis II: Act, because it is perfection, is not limited ex­
cept by potency, which is a capacity for perfec­
tion. Consequently, in any order in which act is
pure, it cannot but be unlimited and unique;
wherever, on the other hand, it is finite and
multiple, it enters into real composition with
potency.
(Actus, utpote perfectio, non limitatur nisi per

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Philosophy of St. Thomas: Metaphysics
potentiam, quae est capacitas perfectionis.
Proinde in quo ordine actus est purus, in eodem
non nisi illimitatus et unicus existit; ubi vero
est finitus ac multiplex, in veram incidit cum
potentia compositionem.)21

21 The 24 theses were approved by Pope Benedict XV on Febru­
ary 25, 1916 and his approval published the following March 7
(feast of St. Thomas).
As for the bibliography on this capital doctrine of act and potency,
it is mountainous and not even a select list will be attempted here.
One aspect of the doctrine, the limitation of act by potency, has
recently been put into historical perspective in an excellent article,
and the interested student might well consult it, namely W. Norris
Clarke, S.J., “The Limitation of Act by Potency: Aristotelianism or
Neoplatonism?” The New Scholasticism, 26, 2 (April, 1952), pp.
167-194.—[Tr.]

+ CHAPTER 7

Essence and Existence

t THIS chapter follows naturally on the preceding;
for the analysis of being into act and potency points clearly
to the still more radical and precise analysis of it under the
terms of essence and existence. The chapter envisages a
conclusion of paramount importance; in Cajetan’s estima­
tion, “the ultimate foundation of all St. Thomas” (maxi­
mum fundamentum doctrinae Sancti Thomae').1 The
conclusion: In created being the principles of essence and
existence differ by a real distinction.
i. The Problem of the Real Distinction
That being has both the aspect of essence and existence
is as much as admitted by everyone; it could hardly be
otherwise, for these aspects are primary data for the intellect
and inseparable from the very notion of being. After all,
being comes to us precisely as “that which is,” in other
words, as something, an essence, endowed with the signifi1 Cf. his Commentary on the Posterior Analytics, chap. 6; English
translation by Eugene Babin (Québec: Les Presses de l’Université
Laval).

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Philosophy of St. Thomas: Metaphysics
cant trait of be-ing or existing. Eliminate one or the other
from the notion of being, and the notion itself is eliminated.
Granted this, we have still to explain in detail how
essence and existence stand to each other, their respective
function in the formation of being, their contribution to
its structure. More specifically, the problem under consid­
eration is the distinction of essence and existence, about
which there are, in the main, two schools of thought: those
who deny the real distinction, and those who affirm it.
If the real distinction is denied, being has no real com­
position, no structural differentiation; it will be much like
a solid rock, all of a piece. To speak of essence and existence
is then mostly just that, a manner of speech, having only
subjective value; for the distinction, even if granted some
foundation in reality, would not exist as such in reality but
only in the mind conceiving it. If, on the other hand,
essence and existence are taken as distinct ontological prin­
ciples, then the ultimate structure of being comes out as a
composition of the two. In this case the distinction of
essence and existence is of course real, yet not so as to render
them independent existents. It cannot be said too often
that this is not a distinction of things having existence be­
fore composition—which makes no sense at all—but of
interdependent principles that constitute but one and the
same being.
Philosophically speaking, the problem of essence and
existence arises out of the formal multiplication and limita­
tion of created beings and, secondarily, out of the relation
of these to uncreated being, unique and infinite. Beings, as
we know them, are many and limited. But whence this
limitation and multiplication, it being understood there

Essence and Existence
203
must be an intrinsic as well as an extrinsic principle of
limitation? The answer, for material beings, we touched on
in connection with the individuation of material substance.
Material beings, we noted, are composed of matter and
form. Matter receives form and in receiving limits it and
makes possible its multiplication.
This solution will not do, however, when it comes to the
multiplicity of pure forms, such as, for St. Thomas and
Thomists generally, the angelic substances. Devoid of mat­
ter, they have obviously to be limited and multiplied
through something else. Which raises the question whether
such beings do not bear composition of another kind to
account for their limitation and multiplication. And the
answer, it turns out, is yes, the composition of essence and
existence. Furthermore, considering limited beings in their
relation to uncreated and unlimited being, we may well ask
how it is that the former retain their individual identity
instead of being lost in pantheistic unity with the one pri­
mary being. Clearly, between limited beings and the in­
finite being with its utter simplicity there must be a dif­
ference of structure; and since the one is all simplicity, the
others, it would appear, must harbor complexity.2
2. Historical Sketch of the Problem

Aristotle does not treat explicitly of the distinction be­
tween essence and existence. This will come as no surprise
when it is remembered that also not expressly considered
by him are formal multiplicity and the relation of limited
beings to pure act. All the same, there is nothing in his
philosophy that opposes the distinction; in fact, considering
2 Cf. Text XII, “Concerning Being and Essence,” p. 276.

2oq
Philosophy of St. Thomas: Metaphysics
on the one hand his general orientation toward the con­
crete, the individual existent, and his looking to essence for
the intelligibility of things on the other, it may be said that
the logical tendency of his thought is toward the real
distinction. However, the first clear intimations of the prob­
lem come not from Aristotle but from the Neo-Platonists.
One of the earlier names to the purpose is Boethius, who,
in a passage that would be much quoted in support of the
real distinction, contrasts “to be” (esse) with “what is”
(quod est).3 It has been argued, however, and successfully it
appears, that Boethius does not use esse in the existential
sense, and certainly he says nothing about the reality of our
distinction.4 For that, one has to look to the (much later)
Arabian philosophers, for instance Alfarabi and Avicenna,
where, at last, the real distinction is unmistakably affirmed.
But Avicenna, in particular, left much to be desired, for
existence is conceived by him as a kind of accident to
essence; which earned him the sharp criticism of his fellowArabian Averroes, and later of St. Thomas. The truth of
the matter is that, notwithstanding these earlier mani­
festations, it remained for St. Thomas to put the doctrine
of the real distinction into proper focus and to give syste­
matic development to the consequences emanating from
it. And yet, one searches him in vain for an explicit and
formal justification of the doctrine, likely because the con­
troversy surrounding it had still to be ignited. Despite that,
3 In Boethius’ phrasing, diversum est esse et id quod est (De
Hebd. PL 64, 1311B).
4 Cf. the authoritative study of M.-D. Roland Gosselin, O.P., Le
“De Ente et Essentia” de S. Thomas d’Aquin, pp. 142 ff. (Biblio­
thèque Thomiste, VIII [Le Saulchoir-Paris: Vrin, 1927]). This is by
all odds the best historical introduction to the whole matter.

Essence and Existence
205
the thesis is implied in all his philosophy, is in fact central
to it, so much that if the appertaining texts are interpreted
in another sense, its entire structure collapses. As for the
polemical phase of the question, this takes shape after St.
Thomas, when Giles of Rome, affirming the reality of the
distinction in a manner far from felicitous, invited the
criticisms leveled against him by Henry of Ghent. Subse­
quently Scotus, and still later Suárez, both denying the real
distinction, would stir interminable debate and discussion.
3. Proofs of the Real Distinction

Though St. Thomas never made it the subject of a formal
treatise, the real distinction does find proof in his writings.
The proof occurs in two principal forms. One starts from
the objective (i.e. conceptual) distinction of essence and
existence; the other turns on the consideration of received
existence, the argument being that a received existence is
really distinct from the essence receiving it.
a) The first proof, from De Ente et Essentia, is to this
effect: Whatever is not included in the concept of the
essence of a thing is extrinsic to the essence, hence super­
added from without; but existence is not included in the
concept of the essence of anything, therefore is added
from without. The only exception, of course, would be a
being whose essence is to exist—God. Because of its im­
portance the proof wants the words of St. Thomas :
Whatever does not belong to the notion of essence or quiddity
comes from without and enters into composition with the es­
sence, for no essence is intelligible without its essential parts.
Now, every essence or quiddity can be understood without any­
thing being known of its existing. I can know what a man or a

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Philosophy of St. Thomas: Metaphysics
phoenix is and still be ignorant whether it exists in reality.
Hence it is clear that the act of existing (esse) is other than
essence or quiddity, unless, perhaps, there is a being whose
quiddity is its very act of existing. And there can be only one
such being, the First Being. . . . Consequently, this excepted,
in every other thing the act of existing is other than its quiddity,
nature, or form.5
b) The second proof, more frequently invoked by St.
Thomas, contrasts created beings, whose essence and exist­
ence are found really distinct, with the first being, where
they are identical—assuming the existence of this being,
God. As developed by St. Thomas the proof, while ad­
mitting of variations, never varies in substance. One state­
ment of it, from the Summa theologiae, is this:

Whatever a thing has besides its essence must be caused either
by the constituent principles of that essence ... or by some
exterior agent. . . .
Now it is impossible for a thing’s being to be caused only by
its essential constituent principles, for nothing can be the
sufficient cause of its own being, if its being is caused.
Therefore that thing, whose being differs from its essence, must
have its being caused by another.®
Thus St. Thomas, who then goes on to draw the con­
clusion that in God, the uncaused being, essence and ex­
istence cannot but be identical; which is what he sets out
to prove in the article from which this passage is cited.
However, if the identity of essence and existence is an un5 De Ente et Essentia, chap. 5; trans, by Armand A. Maurer,
C.S.B., On Being and Essence (Toronto: The Pontifical Institute of
Mediaeval Studies, 1949), pp. 45-46.
6 Summa theol. la, q. 3, a. 4; trans. Pegis, Basic Writings, etc.

Essence and Existence
207
caused being, it necessarily follows that the caused being
does not have this identity, its essence is not its existence;
hence the distinction in view is established, if not explicitly,
at least by implication.
To sum up, because the being whose essence and exist­
ence are identical is unique, all others necessarily bear the
real distinction and are caused by the being which ex­
cludes it.
4. True Sense of the Distinction

Since, generally speaking, objections to the thesis of the
real distinction stem from misinterpretations of it, a correct
understanding of what is involved is very much in order.
a) First, what is this being whose constituent principles
are said to be distinct? It is the concrete substance, the
actual existent, and not the mere possible. Our speculation
bears not on a notion but on a reality.
b) In this reality we distinguish two aspects, two prin­
ciples. One is the subject or essence, the transcendental
“thing” (res). The other, for want of something better, we
may call “existence.” St. Thomas himself refers to the latter
principle indifferently as the “to be as such,” “the act of
being,” and (our more familiar) “existence”—respectively,
ipsum esse, actus essendi, existentia. We say that between
these two, between essence and existence, lies a real dis­
tinction. We mean that the distinction is not merely in the
mind, not just a product of reason, but that it is embedded
in reality, a mark of its structure. Yet a caution must be
sounded. Essence and existence are really distinct, but they
are not pre-existent things which come together to form a
third. In the world of creatures, before being there is neither

2o8

Philosophy of St. Thomas: Metaphysics
essence nor existence, entities which are absolutely incapa­
ble of standing alone. Neither essence nor existence exists
apart—even to say this jars the sensitivity. The only existent
is the being they compose, saving their identity in God.
Once for all, essence and existence are correlative principles
having no reality except as complement of each other.
But how, more precisely, does one complement the
c)
other? On this point St. Thomas and his tradition have
never hesitated; essence and existence serve each other (or,
are related) as potency and act respectively.
Existence (esse), as such, is all act, and for any given
being it is said to be the ultimate act or perfection—ulti­
mate because, as St. Thomas remarks, “to be is the actuality
of all acts, and for this reason it is the perfection of all
perfections.” 7 It is also, though ambiguity haunts the ex­
pression, what is most “formal” with respect to all that is in
a thing; which (to forestall the ambiguity) does not mean it
is a form.8
If existence is act, essence represents potency, a real
capacity for act. It is not, however, the same kind of potency
as prime matter; for in its own order essence is, as matter is
not, something actuated or determinate. The difference
shows well in spiritual substances, in which there is indeed
potency but not prime matter. If St. Thomas speaks of the
“matter” of such substances, he means their essence, which
7 “esse est actualitas omnium actuum et propter hoc est perfectio
omnium perfectionum” (De Potentia, q. y, a. 2, ad 9).
8 For the meaning of “formal” in this context see Etienne Gilson,
Being and Some Philosophers, pp. 170-171; second edition, cor­
rected and enlarged (Toronto: Pontifical Institute of Mediaeval
Studies, 1952).

Essence and Existence
209
is comparable to prime matter because, like the latter, it
too is in potency, though not in quite the same way. The
spiritual essence is in potency to existence, but as essence it
is all act. That is why St. Thomas describes it as “actual
being of a kind, existing in potency.” 9 In their own order
then, both essence and existence function as determining
principle; but existence, and not essence, is ultimate act, last
perfection.
d) The potency of essence, we have said, is a real capacity
for existence. But essence does not receive existence in the
way substance receives a new determination through an
accident. Existence is not, properly, an accident, a supple­
ment to an already constituted being. Rather, existence is
what is most radical, most vital to all being, and essence is
what limits and determines the existence.
Much more, no doubt, could be said to clarify the dis­
tinction of essence and existence. The fundamentals, how­
ever, have been gathered in the foregoing paragraphs, which
we conclude with a word of warning. The translation of
essence and existence into potency and act represents a
special application of the potency-act formula, an applica­
tion in which, under pain of going astray, the analogical
character of these principles has constantly to be watched.
5. Composition of Created Substances, Simplicity

of Uncreated Being

With the distinction of essence and existence now in
hand, it should prove enlightening to compare, more closely,
9 “aliquid ens actu in potentia existons” (De substantiis separatis,
cap. 5, no. 35).

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Philosophy of St. Thomas: Metaphysics
the metaphysical structure of one grade of being with that
of another, the material creature with the spiritual, and
these with God.
a) Material substances have a twofold composition: of
matter and form in their essence, of essence and existence
in their concrete reality. Form actualizes and determines
matter; together they constitute the composite essence of
the material substance, which is further composed with its
ultimate actuality, existence. The principle of individuation
for such substances is matter terminated by quantity, tech­
nically signate matter. To them, accordingly, applies this
arrangement:

what is (quod est) = the individual
by which it is (quo est) = essence
by which it is (quo est) = existence
b) Spiritual substances are simple in essence, that is, not
composed of matter and form. The composition of essence
and existence does, however, appear in them, as of course in
every creature. Regarding individuation, this the subsistent
(or pure) form has of itself—matter, obviously, cannot be
the principle of it here.10 Thus, in the spiritual substance,

what is (quod est) = essence
by which it is (quo est) = existence
10 It might be well to recall here that for a subsistent form to be
individuated does not mean to be divided from other members of
the same species (for in Thomistic doctrine there are no other mem­
bers of the same species) but to be divided from every other species.
This is merely an application of the principle that act is limited by
potency. The subsistent form, being all act in the order of essence,
is necessarily unique, incapable of limitation in the sense of multi­
plication.—[Tr.]

Essence and Existence
211
Essence, then, as appears from the above, can be con­
sidered as a subject {quod), this in the material substance,
or as a formal principle {quo), speaking of the spiritual
substance; whereas existence is always a formal principle,
albeit in a very analogical sense.
c) Uncreated being, God, is absolutely simple. God, this
means, is not distinguishable into subject of existence and
existence of the subject, that is, into essence and existence.
His existence {esse) is self-subsistent and identical with his
essence; moreover it is infinite, from not being limited by
anything at all. It is also necessary, since God’s being ex­
cludes the possibility of its not-being. God, in a phrase St.
Thomas favors, is Ipsum esse subsistens, Subsistent Being
Itself.
Because the essence of God is to exist, some would have
it that in God there is no essence. This is true enough if it
means that his existence is not determined by a formal
principle of any kind, but it is false in the sense that God’s
being has no nature at all, or is an indeterminate infinity.
6. Originality of St. Thomas’ Doctrine of Being
Reading it closely, we should find that St. Thomas’
analysis of being, with its stress on the real distinction of
essence and existence, scores a significant advance over the
Aristotelian analysis. The result, as Professor Gilson relates
in a remarkable study,11 is not simply Aristotle revisited but
Aristotle revised and indeed transformed. In effect, what St.
Thomas achieved was a metaphysics far more original than
it has been given credit for, even by some professing his
11 Namely, L’être et l’essence (Paris: J. Vrin, 1948), most of
which is incorporated into Being and Some Philosophers (cf. note
8 for publisher, etc.).

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Philosophy of St. Thomas: Metaphysics
name. In this connection, it may seem a curious thing but
the persistent tendency of philosophers has been, and history
proves it, to construe being as nature or essence. It is plainly
so in Platonic thought, and even the substance (ousid) of
Aristotle has still the appearances of mere subject of being,
namely essence.
Avicenna, it is true, represents a notable leap forward in
thought as well as in time, only, however, to be castigated
by his fellow-Arabian, Averroes. Yet Avicenna still falls
short of the Thomistic achievement. In his middle position
existence is indeed discriminated from essence, yet essence
again emerges as the basic structural element of being,
upon which existence (the actus existendi) supervenes in
much the manner of accident—a tacking on, as it were.
In time a considerable number of Scholastics, under the
influence of Scotus and Suárez, would also commit them­
selves more or less wittingly to the essentialist conception
of being.12 The same is true of modern philosophy, possibly
more so; from Descartes to Hegel, with Wolff and Kant as
intermediaries, the essentialist position is in varying degree
in command.
But when we take stock of St. Thomas, a new turn of
thought appears. Not only does he ceaselessly affirm that in
created beings existence is really distinct from essence—of
which, for that matter, he was never in doubt—but also
that existence is act, of all perfections of being the ultimate
one, and that God himself is Ipsum esse subsistens, Sub­
sistent Being (existence) Itself. Being, accordingly, whether
of God or of creatures, is pre-eminently existence. So that
12 Cf. Being and Some Philosophers, chap. 3, “Essence and Exist­
ence” (discussion of Avicenna, Scotus, and Suárez).

Essence and Existence
213
it is more in keeping with the spirit of St. Thomas to say—
though the converse, too, is perfectly correct—that being is
an existence determined by an essence. We need not hesi­
tate, then, to describe his metaphysics as existentialist,
though not, it should be emphasized, in the sense that
marks certain contemporary philosophies. Indeed, it is the
existentialist character of St. Thomas’ thought which sets it
off from every essentialist or rationalist philosophy, ancient,
Scholastic, and modern, and lends it the stroke of high
originality.

t CHAPTER 8

Causality

t BEING has a dynamic as well as a static aspect; it
not only is, but is active, a principle of activity: in a word,
cause. This is what we have now to examine: being in its
dynamic character, being as cause. Here again the problems
are many and complex. Cause is one of the most frequently
used notions in human thought; it is also one against which
modern philosophy has directed some of its most pointed
criticism; besides that, what the early philosophers taught in
the matter is not easily gathered and sifted.
The chapter divides into three parts. First, as usual, we go
to Aristotle and St. Thomas for their basic ideas on caus­
ality, and these in proper perspective. The conception thus
gained is next put to test against the typical modern
criticism of causality. The chapter then concludes with
some extended remarks on the first cause, the consumma­
tion of the metaphysics of being.
I. CAUSALITY IN ARISTOTLE AND
ST. THOMAS
Neither Aristotle nor St. Thomas has left a complete
treatise on causality. Their thoughts on the subject, such as

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we have them, are fragmentary and, frankly, more often
developed by occasion of other matters instead of inde­
pendently. Still, it is possible to marshal these thoughts
into two broad units, which reflect two principal preposses­
sions: i) those which tell of causality as it relates to the
doctrine of science, and 2) those which speak of it under the
study of God (transcendent causality). The elaboration of
causality in function of science is practically all Aristotle’s,
whereas its elucidation in reference to the study of God
comes much more from St. Thomas.
1. Causality in Scientific Explanation 1

Aristotle’s doctrine of the role of causality in scientific
explanation is found, principally, in two works, the Posterior
Analytics and the Physics, Book II in particular. In these
studies two conclusions stand out, which for the present
purpose it will suffice to pass in quick review.
a) Science is knowledge through the causes. This, in fact,
is Aristotle’s very definition of science, expounded in the
Posterior Analytics and echoed again and again in other
works, especially in Book II of the Physics and in Book B
of the Metaphysics. In the Latinized Aristotle,

scientia est cognito per causas.
What Aristotle is saying is that we “know” (have science of)
1 It may not be amiss to remind the reader that the author is
speaking of “science” and “scientific explanation” in the Aristotelian
sense, which is not always the precise sense these terms were to
bear in the modem epoch. Yet all science, however understood, re­
veals a fundamental kinship. For some remarks in point see the
author’s Cosmology (Vol. II of the present series), pp. 82-86; trans,
by John A. Otto (St. Louis: B. Herder Book Co., 1958).—[Tr.]

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217
a thing when we know the cause (or causes) of it. Cause is
the proper principle of scientific explanation.
Well and good, but we should also note what Aristotle is
not saying. Neither he nor St. Thomas would have us look
upon cause as a logical tool only. True, their doctrine of
causality finds foremost expression within the framework of
logical expositions, but this is not to suggest that they
regard causality as void of validity in the real world. Quite
the contrary; cause answers to the "why” of a thing and
serves as principle of explanation for the very reason that it
is, first of all, a principle of reality. Indeed, the principle
of causality is essentially a principle of reality. St. Thomas
says as much many times over; cause, he insists, as though
anticipating future denials, bears directly on esse, existence,
which means it bears on what is by nature most real, most
concrete. Witness, for example, “the word ‘cause’ implies
influence on the being {esse) of the thing caused.” 2
b) Causal explanations in the sciences are possible under
all four causes. This proposition is a hallmark of Aristotelianism. Since the causes are four in kind, so will be the
causal explanations. In physical doctrine demonstration is
by all four causes: material, formal, efficient, and final.
Other sciences proceed more restrictively. Mathematics
takes in formal cause only. Metaphysics, in the main,
focuses on formal, efficient, and final cause.
c) In summary, cause may be considered in the order of
objective reality and in the order of explanation or demon­
stration. Its primary order is that of reality; here, cause is
precisely what gives a thing its being, and this through any
of the four causes. In the derivative order of explanation
2 In V Metaph. lect. 1, no. 751.

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Philosophy of St. Thomas: Metaphysics
cause is what gives the “why” or reason of a thing, and
this, too, from each of the four causes.
Essentially, then, a cause is “that on which a thing de­
pends for its being or its becoming.” Which, in St. Thomas,
is:

Causae autem dicuntur ex quibus res dependent secun­
dum esse vel fieri.3

Analyzing this definition we find that causality neces­
sarily implies these three particulars:
1) a real distinction between cause and effect
2) a real dependence of being
5) consequently, priority of the cause to the effect

2. Causality in Theology
So far we have spoken of cause as it impinges on the
order of physical explanation, the order of experience. But
this application of causality, even though it satisfies the true
notion of cause, is not the whole of it. Causality in its wider
range, in its metaphysical or transcendent mode, is seen in
the study of God, where the central problem is precisely his
existence, or the demonstration of it. Aristotle had already
provided such a demonstration, the argument for the prime
mover, fortifying it with all the rigor of his philosophical
genius.4 This famous argument, stripped of its cosmo­
logical overlay, is retained by St. Thomas, who accords it
first place in his Five Ways, still the classical proofs of God’s
3 In I Phys. lect. 1, no. 10 (Editio A. M. Pirotta [Naples: M.
D’Auria, 1953]).
4 For Aristotle’s development of the argument, see Books VII &
VIII of the Physics and Book A of the Metaphysics.

Causality
21g
existence.® We do not intend, however, to make a detailed
study of the Thomistic proofs. What follows is but three
of them, and these in sketch: the argument for the prime
mover (First Way), the proof from the degrees of being
(Fourth Way), and, in barest form, the proof from finality
(Fifth Way). The second and third proof, from causality
and contingency (possible being), are mentioned in passing.
a) The argument for the prime mover. For the details of
the argument as presented by Aristotle the reader is re­
ferred to the analysis we made of it in an earlier volume.®
St. Thomas, as we have said, keeps only the essentials of the
argument, namely its metaphysical bases, which are not
undermined by shifts in physical theory.
The argument, both in Aristotle and St. Thomas, begins
with the fact of motion. It encompasses not only local
motion, or the physical changes observable by the senses,
though these of course come first to mind. Any becoming,
any transition from potency to act can be taken as a starting
point. If St. Thomas cites a physical change, this is no more
than a pedagogical device.
Given motion, two principles are introduced in proof of a
prime mover. First, “whatever is moved, is moved by an­
other”—quidquid movetur ab alio movetur. This is the
principle of causality in the more usual Aristotelian for­
mulation of it. Motion, the principle intends, involves
transition from potency to act, which is not possible except
by agency of another, by a cause in act.
5 For the Five Ways of St. Thomas, see Summa theol. la, q. 2,
a. 3.
6 Namely Cosmology (Vol. II of the present series), chapter 8,
“Proof of the Prime Mover.”

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Philosophy of St. Thomas: Metaphysics
The second principle is “there can be no infinite regress
in an essentially ordered series of movers.” One mover may
be moved by another, but if the series of ordered movers
were infinite, there would be no first or unmoved mover,
consequently no second or moved movers. More generally,
in every order there must be a first, which, as principle or
originator of the order, has necessarily to transcend it, to be
outside of it. Thus, the order of moved movers requires a
first mover, moved by no other. This mover, concludes St.
Thomas, all men identify with God.
Such, in broad stroke, is the argument for the prime
mover, which, it is plain, rests on the principle of causality.
Of this principle we shall have more when addressing our­
selves to the critical justification of it. What we wish here to
remark is that the second and third proof of St. Thomas
(his Second and Third Way) follow the same general pat­
tern. The second proof begins with the order of efficient
causes, such as experience shows us, and argues to a first
efficient cause, which, transcending every series of caused
causes, is caused by no other. The third proof proceeds from
the palpable contingency of things to the affirmation of a
first necessary being.7
b) The proof from degrees of perfection. This proof de­
parts, or so it may seem, from the principle of causality.
Whether or no, here for the moment is the thread of it.
The things of experience exhibit varying degrees of
perfection. All things, for example, are good, but some are
better; and all are true, but some are truer, etc. However,
7 St. Thomas, it may be worth noting, begins all his proofs with a
fact of experience, which, in the Third Way, is the experience of
contingent reality or, in the terminology of St. Thomas, “possible”
being.—[Tr.]

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221
not all perfections are to the purpose of the argument—
only those which do not of their nature imply limitation,
pure perfections, as is commonly said. Perfections of this
kind are not confined to categorical being, but are to be
found in being generally. Pre-eminently they are the tran­
scendentals: the one, the true, the good, and of course being
itself. Because of their transcendental character they are
realized analogically from being to being.
This is the empirical premise of the proof, the degrees of
perfection. Then to the principle on which the proof rests,
namely: a perfection is spoken of as more or less only in
reference to something that has the perfection to a maxi­
mum. Consequently, there is something which is most true,
most good, and (it follows) most being.
But (to complete the proof) that which is the maximum
in any order of perfection is the cause of all perfections
existing in that order. Hence, there is something which is to
all other beings the cause of their being, their goodness,
their every perfection; and this we name God.8
Thus the proof, the interpretation of which has occa­
sioned much controversy. On the surface the appeal, it
would seem, is not to the principle of causality: from the
degrees of a perfection the maximum of this perfection is
immediately inferred. On the lips of St. Thomas, however,
the proof is not complete, and does not formally terminate
in God, until the maximum in a given order of perfection is
set forth as the cause of all lesser realizations of the same
perfection. Consequently, the principle of participation,
which is admittedly in the foreground, still implies the
8 There is no completely satisfactory substitute for the original
Latin of this Fourth Way, which, it seems, has given the com­
mentators more trouble than any other.—[Tr.]

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Philosophy of St. Thomas: Metaphysics
principle of causality. All the same, the proof from degrees
of being does throw new light on the relation of creatures
to God, presenting a fuller view, as it were, than appears
through the avenue of causality alone. St. Thomas, for that
matter, was not one to depreciate the doctrine of participa­
tion, his treatise on God being inspired by it throughout.9
Even so, we must not find in this treatise what is not there,
intimations of a metaphysics that would oppose and perhaps
supplant the metaphysics via causality. In St. Thomas,
participation and causality are not pitted against each other,
nor does the latter have to give way to the former, as
though they were incompatible.
b) The proof from finality. This proof, last of the Five
Ways of St. Thomas, starts from the finality and order seen
in the physical universe.
Where (runs the argument) there is order, there is in­
tention; and if intention, intelligence. Ultimately, then,
there must be some intelligent being which directs all things
of nature to their end. This being is God.
This proof is much favored in more popular works on the
existence of God, and there is no doubt that the presence of
order in the world is a theme well-suited to the purpose.
The proof, for all that, is not without its pitfalls; to make
its mark it has to be handled with care.
d) Conclusion: causal dependence as the common ele­
ment in the proofs of God. The arguments presented consti­
tute distinct proofs demonstrating, each from its particular
standpoint, the existence of God, the first cause. Yet all the
proofs have this in common: the metaphysical principle
9 A most notable example being the third argument in the capital
demonstration of identity of essence and existence in God; see
Summa theol. la, q. 3. a. 4.

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223
that contingent being, or being which does not have its
sufficient reason of itself, presupposes being that does, the
being that exists of itself and to which contingent being is
related by the bond of causal dependence. Being which is not
of itself can only be of another—of another that is of itself.
All theology, not to say philosophy, rests on this funda­
mental, the causal inference. Is this inference legitimate,
well-founded? The question has now to be examined.
II. CRITICAL JUSTIFICATION OF CAUSALITY

The beginnings of the modem onslaught on causality are
clearly discernible in the Nominalists of the late Middle
Ages. Continued by the Cartesians, the attack culminated in
complete repudiation of causality by the British Empiricists
of the 18th century. Thereafter, modern philosophy was to
take it for granted that causality is but an illusion, or at best
a subjective category. Among the circumstances which made
for this radical denouement was the stand of some Car­
tesians that God alone can be a cause in the true sense of
the word, in which case secondary causality (the name for
the causality of creatures) had of course to be watered down
considerably. And so it was—reduced to a mere occasion for
God to act. Causality becomes occasionalism, with a capital,
to be sure.
By far the boldest stroke, however, came from such as
Hume, in consequence of the phenomenalist interpretation
of experience. Here, for the moderns, cause was system­
atically reduced to a mere relation of succession. To illus­
trate: I roll a billiard ball against another. The second ball
begins to move. What is the explanation? The first ball,
you naturally say, caused it (the second) to move. But the
phenomenalist Hume will not have it so. All you saw (he

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Philosophy of St. Thomas: Metaphysics
argues, rightly enough) was two motions, one after the
other. And he allows that under the same or similar condi­
tions the same thing will happen; one motion will succeed
another, or one event another. Which is precisely the reason
why, in his view, we come to regard the relation between
the two motions as a relation of causal dependence and
eventually, by some psychological habit, translate this (as­
sumed) dependence into the absolute principle that “what­
ever is moved, is moved by another.” So doing, however,
we have gone beyond the presentations of sense; and this
the phenomenalist view of things does not permit.
Kant, for his part, had every intention of safeguarding
the necessary and universal character of the causal relation.
But having posited causality as no more than an a priori
(i.e. subjective) category, a mere law of the mind, he could
not but deny that it had any objective validity. The truth is
that Kant, even as his predecessors, fell victim to the
phenomenalist view of sense knowledge; like them he denies
in principle that the intellect can derive the intelligible
from the sensible. Against these dissenting voices, which we
have hardly more than called attention to, the reality or
objectivity of causality must be uncompromisingly main­
tained; and maintained both in the realm of experience in
the strict sense, and in the realm of metaphysics as one of
its first principles.
i. The Experience of Causality

The causal relation is, in the first instance, come upon as
a fact of experience. One thing, to all appearances, moves
another, effects a change in another; we see this constantly,
accept it implicitly. I touch the flame of a candle; instantly

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225
I feel my hand burning, and instinctively lay the burning
to the flame. Instances of this kind are multiplied a thou­
sand times daily. Granted, the cause is sometimes assigned
mistakenly, for sensible experience can be complex and
difficult to analyze. Yet there are evidences of causal de­
pendence, especially within my conscious self, so direct and
unimpeachable that I would find it extremely difficult, if
not impossible, to disbelieve them. Suppose you want to
raise your arm; and now you have raised it. Is there anything
more certain than that it moved from one position to an­
other and that you were the one who moved it, caused its mo­
tion? The whole march of practical life and, it is well to add,
of scientific endeavor rests on the supposition that things
in this world, the world of experience, act upon each other.
We do more, however, than experience the causal se­
quence, the relation of real dependence of one thing upon
another. We generalize it, so that under the same set of
circumstances we confidently expect the same sequence,
the same dependence. Metaphysics, however, goes still
further, to the affirmation of causality as an absolute prin­
ciple. With the recognition and enunciation of this
principle causality appears in full view, and not merely
under the aspect of generalized experience; for what has
then been seen is that causality, under certain conditions, is
a law, an absolute requirement, of being.

2. The Principle of Causality

This principle refers, as a rule, to efficient causality,
which is the causality that usually comes under attack, as
in the earlier-mentioned criticism of it. Of the principle
so understood, two cardinal proofs can be given, one more

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Philosophy of St. Thomas: Metaphysics
particular in scope, the other more inclusive and at the
same time more penetrating.
a) Whatever is moved, is moved by another. This, as
noted before, is how the principle of causality is usually
formulated in Aristotelian thought: whatever is moved, is
moved by another. While the principle can be vindicated
on physical as well as metaphysical grounds, we shall speak
only of its metaphysical basis, namely, the resolution of
motion into act and potency;10 for it is from the considera­
tion of act and potency that the principle receives its high­
est support.
Assume, then, that motion is a fact—not just an illusion;
furthermore, that it is a transition from potency to act,
which for all practical purposes means any kind of be­
coming. We then argue:
Motion is a transition from potency to act. But a being
in potency does not become actual by itself but only by
some being already in act.11 No being, moreover, can be in
act and potency at the same time and in the same respect.
Consequently, the going from potency to act can only be
effected through the agency of another, through a being in
act. Thus the principle is established: whatever is moved,
is moved by another—quidquid movetur, ab alio movetur.12
b) Being which is not of itself, is necessarily of another.13
10 Which is precisely what St. Thomas does in the First Way; see
Summa theol. la, q. 2, a. 3.—[Tr.]
11 “de potentia autem non potest aliquid reduci in actum, nisi
per aliquod ens in actu” (from the First Way).
12 As St. Thomas has it, “Omne ergo quod movetur, oportet ab
alio moveri’’ (First Way).
13 In the clause “being which is not of itself” the words “of itself”
render the expression “ens per se” or “per se ens.”—[Tr.]

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227
To argue this proposition we do not set out from change or
motion but from being which is not of itself, from being,
this means,whose existence does not necessarily follow from
its nature or essence. Such being is contingent (as against
the necessary); nothing in its nature says it must exist, it can
exist and it can just as well not exist. All beings encom­
passed by experience (by the senses) are contingent.
Now, what is to be inferred from contingent being? Con­
sidered in itself such being, as we have said, can exist and
just as well not exist; its essence entails neither one nor the
other. Consequently, its existence is in some manner an
addition to its essence. Whence it follows that contingent
being is a union or composition of diverse elements: essence
and existence. But things which in themselves differ from
each other cannot, as different, constitute a unity. If, then,
they are found as one, as a unity, it can only be through
some extrinsic cause having united them.14 And such is
contingent being, a unity or composition of diverse ele­
ments, hence a being that needs must have a cause.
c) Justification from the principle of sufficient reason.
The foregoing conclusion on the necessity of a cause for
contingent being may also be arrived at by considering the
principle of causality as an application of the principle of
sufficient reason. We would then proceed as follows. Every
being that does not have its sufficient reason from itself
must have it from another. The contingent is such a being;
the sufficient reason of its existence is not in itself, in its
essence, hence must be in another. Which comes to saying
14 In the Latin of St. Thomas, “quae enim secundum se diversa
sunt, non conveniunt in aliquod unum, nisi per aliquam causam
adunantem ipsa” (Summa theol. la, q. 3, a. 7).

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Philosophy of St. Thomas: Metaphysics
that the contingent is caused; causality, once again, is
demanded.
d) Ultimate ground of the principle of causality. It is
perfectly true, as more than one author has observed, that
the principle of causality is not strictly analytical; the
predicate “being of another” is not expressly contained in
the subject “being which is not of itself.” More concretely,
I can have the notion of contingent being, say of this book
before me, without adverting or tracing it back to its cause.
But granted this, it must still be maintained that, deriva­
tively, the principle of causality is self-evident (the mean­
ing of “analytical”), for causality follows on the nature of
the contingent somewhat in the manner of a necessary
property. No sooner, that is, do I grasp “being which is not
of itself” and “being which is of another” than I recognize
that the two notions imply each other, that “being which is
not of itself, is of another.” St. Thomas says as much when
he writes :
Though relation to its cause is not part of the definition of a
thing caused, still it follows as a result of what belongs to its
nature. For, from the fact that a thing is being by participation,
it follows that it is caused. Hence such a being cannot be with­
out being caused, just as man cannot be without having the
faculty of laughing.15
What St. Thomas has just said rests, ultimately, on the
impossibility of more than one “being which is not of
another.” Clearly, “being which is not of another” can only
be “of itself.” If, then, the contingent was not caused, it
would be a “being that is of itself” and thus there would be
more than one “being that is of itself.” Yet “being that is
15 Summa theol. la, q. 44, a. 1, ad 1 (trans. Pegis, Basic Writings,

etc.).

Causality
229
of itself,” whose nature in consequence is to be, cannot but
be an only being. For the infinite has no similar; God is
one. Accordingly, the contingent cannot but be caused—
under pain of contradiction.16
III. THE FIRST CAUSE

It is not our purpose, here, to give even the outlines of a
treatise on God; this would take us beyond the limits we
placed upon our study, intended to be no more than a
general introduction to metaphysics. Thus, with the pre­
ceding considerations on causality we have for all practical
purposes come to the end. What follows is but by way of
summation, presented, however, with a view to showing
that the thesis of a first cause, of a being that exists of itself,
is not an alien accretion to the Thomist philosophy of being
but its logical crown and consummation.
We saw, at the outset, that the first presentation to the
intellect is that of being. Proceeding to a more formal
consideration of being, we detailed its structure and deter­
mined its properties, the transcendentals. Next, we attended
to those special modes of being that are most familiar, the
categories or predicaments, and saw that substance is the
fundamental mode, from which the others issue according
to a certain ontological sequence. Came then the analysis
of change, which opened up a new vista on being, its dis­
tinction into act and potency. And then, to account for the
limitation and multiplicity of being, its real composition of
essence and existence was found imperative.
The multiplicity of being leads into our final considera10 Here we see again the prime importance of the principle of
contradiction; yet even this principle has not always been left its
absolute inviolability.—[Tr.]

2^o
Philosophy of St. Thomas: Metaphysics
tions: on the first cause, on being that exists of itself.
Reflecting on the beings of experience, we cannot but mark
their imperfection, their essential poverty and insufficiency,
unable as they are to account for themselves. They change,
they are limited; and though they have being, they have it
not of their nature, of themselves, but are dependent
through and through, radically. It is just this lack, this
indigence of being that looks to the existence of a first
being, cause of all others. To this end, the various proofs.
From being that is moved we are inexorably led to being
that is not moved, the first unmoved mover; from being
that depends on the efficient causality of another, to a first
efficient cause; from contingent being, to a necessary being;
from imperfect being, to a perfect being; from beings
which tend toward an end, to a supreme ordaining intelli­
gence. By whatever approach, the term is the same; the
insufficient leads of necessity to the self-sufficient, whose
name is God, whose sufficiency supplies for the insufficiency
of all that is not God.
But to round out the Thomistic metaphysics of being two
further points should be brought home: first, that God’s
essence is his being or, which comes to the same, his being
is of itself (per se);17 and second, that every other being is
necessarily a being created by God, or being by participa­
tion.18 Either way, then, whether from God to creatures or
from creatures to God, the science of being comes full
circle.19
17 Cf. Summa theol. la, q. 3, a. 4.
18 Cf. Summa theol. la, q. 44, a. 1.
19 Cf. Text XIII, “That in God Essence and Existence Are the
Same,” p. 287.

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231
That God’s essence, to take the first point, is the same as
his being is readily shown. In creatures, as we have seen,
essence and existence are necessarily distinct. But in God
they are necessarily identical. For God is the first efficient
cause and therefore cannot have received existence from
another. Nor can he have received it from himself—nothing
causes itself. Consequently, existence must be his by nature
or essence. Devoid, moreover, of all potentiality, there can
be nothing in his essence save the pure act of his existence.
The first existent, God in short can but be by his essence,
and this in virtue of the very laws of participation. Impos­
sible, then, that in God essence be one thing and existence
another.20
Turning to creatures, we must conclude that every being
that is not God must have been created by God. For, when
a thing is found to exist in a subject by participation, it
must have been caused by a being in which this thing exists
of itself. But God is the being that exists of itself, and of
such being there can be but one. It follows that all things
that are not God are not their being (their nature is not
their existence), but only participate in being. Consequently,
and finally, whatever is diversified according to its participa­
tion in being is caused by a first being which is perfect not
by participation or degrees, but absolutely.21
20 “Impossibile est ergo quod in Deo sit aliud esse, et aliud eius
essentia” [Summa theol. la, q. 3, a. 4).
21 In St. Thomas’ statement, “Necesse est igitur quod omnia quae
diversificantur secundum diversam participationem essendi . . .
causari ab uno primo ente, quod perfectissime est” [Summa theol.
Ia, q. 44, a. 1).
Cf. Text XIV, “Whether It Is Necessary that Every Being Be
Created by God?” p. 291.

2j2
Philosophy of St. Thomas: Metaphysics
Viewed against this perspective of Creator and creature,
the whole metaphysic of the real appears in striking sim­
plicity. At the summit is the principle to the whole, being
that exists of itself, whose essence is to exist. Below, in
radical dependence on this being, are the beings that cannot
exist of themselves and therefore hold their existence from
the being that does so exist. Such are the essentials, epito­
mized for us in the third of the 24 Thomistic Theses
enunciated by the Sacred Congregation of Studies: “Where­
fore, by the absolute nature of his existence, God alone
subsists, He alone is utterly simple. All other things which
participate in his being have a nature that restricts their
being, and are composed of the really distinct principles of
essence and existence.” 22
Just how, on the other hand, St. Thomas conceives this
participation in the being of God, how it procures the
creature the proper ontological status, all this is here left
unsaid. These particulars are better reserved to the treatise
on God, where being is scrutinized more thoroughly than is
feasible in the introductory metaphysics. Suffice it to have
brought the reader to the mere threshold of these further
perspectives.23
The whole philosophy of being stems on the recognition
that in God there is identity of essence and existence;
22 In the language of the Sacred Congregation, “Quapropter in
absoluta ipsius esse ratione unus subsistit Deus, unus est simplicis­
simus; cetera cuncta quae ipsum esse participant, naturam habent
quae esse coarctatur, ac tanquam distinctis realiter principiis, es­
sentia et esse constant.”
23 On the subject of participation the interested (and knowledge­
able) reader will do well to consult L. B. Geiger, La participation
dans la philosophie de saint Thomas d’Aquin (Paris: J. Vrin, 1942).

Causality
2 33
whence it is that he is the fullness of being, fullness in
which all other beings but participate. In the following
passage St. Thomas, in a mood not unlyrical, finds this
sublime (his word) truth adumbrated in the revelation God
made of his name to Moses; it is a passage that will serve
as fitting conclusion to our study:

This sublime truth [he writes] Moses was taught by the Lord;
for when he asked the Lord: “If the children of Israel should
say to me: What is His name? what shall I say to them?” the
Lord answered: “I am who am. . . . Thus shalt thou say to the
children of Israel: He who is hath sent me to you” (Exod.
3:13,14), thus declaring His own proper name to be He who is.
Now, every name is appointed to signify the nature or essence
of a thing. Wherefore it follows that God’s very existence itself
is His essence or nature.24
24 Contra Gentiles, I, 22; trans., with an Introduction and Notes,
by Anton C. Pegis under title On the Truth of the Catholic Faith,
Book One: God. A Doubleday Image Book (Garden City, N. Y.:
Doubleday & Co. Inc., 1955. Fourth Printing, May, 1958).

TEXTS

PREFATORY REMARKS
t THE principal metaphysical work of St. Thomas is
undoubtedly the Commentary on the Metaphysics of
Aristotle. We have, accordingly, excerpted sizable portions,
specifically Texts I-VIII inclusive, which treat of the fol­
lowing: the prerogatives of metaphysics (I); its “subject”
(II) ; the transcendental one and the principle of number
(III); the first principle of demonstration (IV); the princi­
pal modes of being (V); substance (VI); act and potency
(VII); and God as life (VIII). These are followed by some
texts on the transcendentals gathered from other sources,
namely, De Potentia (IX), Summa Theologiae (X), and De
Veritate (XI). For the problem of essence and existence the
choice had obviously to be De Ente et Essentia (XII).
Finally, the two Summas provide two most excellent Texts
(XIII-XIV) which show the contrast between God and
creatures, i.e. between being which is of itself and being
which is by participation.

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Philosophy of St. Thomas: Metaphysics
The texts we have chosen, as indeed St. Thomas in
general, present special difficulties to the translator. In
particular, the De Ente et Essentia and the Commentaries
on Aristotle, including the Metaphysics, do not have the
flow and finish we find elsewhere in St. Thomas, above all
in the two Summas. This, of course, is to be expected; for
in De Ente et Essentia we have to do with an early work,
and in the Commentaries we have simply to reckon with
the method St. Thomas saw fit to follow, the line-by-line
exegesis of Aristotle. Nevertheless, precisely as commen­
taries the work on Aristotle shows as much the hand of the
master as do the two Summas, where St. Thomas was free
to give more rein to his own genius. The difficulties of
translation, however, have also to be traced to the short­
comings of the present editions of St. Thomas, especially
of the Commentaries; more than one passage, in its present
form, must be left hanging until better readings become
available. But for all that, the essential St. Thomas is never
in doubt, whether in the texts we have assembled or more
generally in the editions of his works.
[The texts are reprinted in English from individual
sources. These have been mentioned in the Acknowledg­
ments at the beginning of this volume and are again
identified and acknowledged in the course of the texts.—
Translator’s note.]
I. THE PREROGATIVES OF METAPHYSICS1

(In I Metaph. lect. 3, nos. 53-65)
Among the passages which reveal most clearly Aristotle’s
mind on the nature of the supreme science must be counted
1 The translation of Texts I-VIII is quoted from Commentary on
the Metaphysics of Aristotle, 2 Vols. Translated by John P. Rowan,

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239
chapters 1 and 2, Metaphysics, Book A. From St. Thomas’
Commentary in point we have drawn the part that treats of
the chief prerogatives of this science, namely that it is
speculative, free, suprahuman, and the most honorable of
all sciences. The first two prerogatives stem from the abso­
lutely disinterested character of metaphysics, from the fact
that it is not ordered to anything but itself; hence it is free
and merits the name of speculative science. Moreover, it is
not sought in view of the practical necessities of life, and
for this reason it cannot be regarded as a possession of the
human realm pure and simple; it transports us to the level
of the divine. Appreciations like these bear eloquent testi­
mony to the rare esteem in which Aristotle held meta­
physical wisdom. (Collate with supra, “Metaphysics As
Wisdom,” p. 5).
A. Metaphysics is a speculative science
53. No science in which knowledge itself is sought for its
own sake is a practical science, but a speculative one. But that
science which is wisdom, or philosophy as it is called, exists for
the sake of knowledge itself. Hence it is speculative and not
practical. He proves the minor premise in this way. Whoever
seeks as an end to escape from ignorance tends toward knowl­
edge for itself. But those who philosophize seek as an end to
escape from ignorance. Therefore they tend towards knowledge
for itself.
54. That they seek to escape from ignorance is made clear
from the fact that those who first philosophized and who now
philosophize did so from wonder about some cause, although
they did this at first differently than now. For at first they won­
dered about less important problems, which were more obvious,

Copyright Henry Regnery Company, 1961. The texts are reprinted
by permission of Henry Regnery Company, Publishers.—[Tr.]

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Philosophy of St. Thomas: Metaphysics
in order that they might know their cause; but later on, pro­
gressing little by little from the knowledge of more evident
matters to the investigation of obscure ones, they began to raise
questions about more important and hidden matters, such as
the changes undergone by the moon, namely, its eclipse, and
its change of shape, which seems to vary inasmuch as it stands
in different relations to the sun. And similarly they raised ques­
tions about the phenomena of the sun, such as its eclipse, its
movement and size; and about the phenomena of the stars, such
as their size, arrangement, and so forth; and about the origin
of the whole universe, which some said was produced by chance,
others by an intelligence, and others by love.
55. Now, it is evident that perplexity and wonder arise from
ignorance. For when we see certain obvious effects whose cause
we do not know, we wonder about their cause. And since won­
der was the motive which led men to philosophy, it is evident
that the philosopher is, in a sense, a philomyth, i.e. a lover of
myth, as is characteristic of the poets. Hence the first men to
deal with the principles of things in a mythical way, such as
Perseus and certain others who were the seven sages, were called
the theologizing poets. Now, the reason why the philosopher
is compared to the poet is that both are concerned with won­
ders. . . . And since wonder stems from ignorance, they were
obviously moved to philosophize in order to escape from ig­
norance. It is accordingly evident from this that “they pur­
sued’’ knowledge, or diligently sought it, only for itself and
not for any utility or usefulness.
56. Now we must note that, while this science was first desig­
nated by the name “wisdom,” this was later changed to the
name “philosophy,” since they mean the same thing. For while
the ancients who pursued the study of wisdom were called
sophists, i.e. wise men, Pythagoras, when asked what he pro­
fessed himself to be, refused to call himself a wise man as his
predecessors had done, because he thought this was presump-

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241
tuous, but called himself a philosopher, i.e. a lover of wisdom.
And from that time the name “wise man” was changed to
“philosopher,” and “wisdom” to “philosophy.” This name also
contributes something to the point under discussion, for that
man seems to be a lover of wisdom who seeks wisdom, not for
some other reason, but for itself alone. For he who seeks one
thing on account of something else, has greater love for that
on whose account he seeks than for that which he seeks.
57.............................................................................................

B. Metaphysics is a free science
58. Aristotle now proves the second attribution, namely, that
this science is free; and he uses the following argument: that
man is properly said to be free who does not exist for someone
else but for himself. For slaves exist for their masters, work for
them, and acquire for them whatever they acquire. But free men
exist for themselves inasmuch as they acquire things for them­
selves and work for themselves. But only this science exists for
itself; and therefore among all the sciences only this science is
free.
59. Now we must note that this can be understood in two
ways. In one way, the expression “only this” may indicate every
speculative science as a class. And then it is true that only this
class of science is sought for itself. Hence, only those arts which
are directed to knowing are called free [or liberal] arts, whereas
those which are directed to some useful end attained by action
are called mechanical or servile arts. Understood in another way,
the expression may specifically indicate this philosophy or wis­
dom which deals with the highest causes; for the final cause is
also one of the highest causes, as was stated above [no. 51].
Therefore this science must consider the highest and universal
end of all things. And in this way all the other sciences are
subordinated to it as an end. Hence only this science exists in
the highest degree for itself.

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Philosophy of St. Thomas: Metaphysics

C. Metaphysics is not a human science [possession]
60. Aristotle proves this thesis by the following argument.
A science which is free in the highest degree cannot be a pos­
session of that nature which is servile and subordinate in many
respects. But human nature is servile “in many respects,” i.e.
in many ways. Therefore this science is not a human possession.
. . . For man has as his possession what he can have at his com­
mand and use freely. But that science which is sought for itself
alone, man cannot use freely, since he is often kept from it be­
cause of the necessities of life. Nor again is it subject to man’s
command, because man cannot acquire it perfectly. Yet that
very small part of it which he does have outweighs all the things
known through the other sciences.
61. Next he rejects the error of a certain poet, Simonides,
who said that it is proper to God alone to have the honor of
desiring that knowledge which ought to be sought for its own
sake and not for the sake of something else. But it is not fitting
that man should not seek knowledge which is in keeping with
his own condition, namely, that which is directed to the neces­
sities of life required by man.
62. Now Simonides’ error came from that of certain poets
who said that the Deity is envious, and that since He is envious
He does not desire that the things which pertain to His honor
should be shared by all. And if God is envious of men in other
things, He is rightly more so in this case, i.e. in the case of the
science which is sought for its own sake, which is the most
honorable of all the sciences. . . .
63. But the basis of this opinion is most false, because it is
not fitting that any divine being should be envious. This is evi­
dent from the fact that envy is sadness at someone else’s pros­
perity. But this can occur only because the one who is envious
thinks that someone else’s good diminishes his own. Now it is

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245
impossible that God should be sad, because He is not subject
to evil of any kind. Nor can His goodness be diminished by
someone else’s goodness, since every good flows from His good­
ness as from an unfailing spring. Hence Plato also said that
there is no envy of any kind in God. But the poets have lied not
only in this matter but in many others, as is stated in the com­
mon proverb.

D. Metaphysics is the most honorable of all sciences
64. That science [he argues] which is most divine is most
honorable, just as God Himself is also the most honorable of
all things. But this science is the most divine, and is therefore
the most honorable. The minor premise is proved in this way:
a science is said to be divine in two ways, and only this science
is said to be divine in both ways. First, the science which God
has is said to be divine; and second, the science which is about
divine matters is said to be divine. But it is evident that only
this science meets both of these requirements, because, since
this science is about first causes and principles, it must be about
God; for God is understood in this way by all inasmuch as He
is one of the causes and a principle of things. Again, such a
science which is about God and first causes, either God alone
has or, if not He alone, at least He has it in the highest degree.
Indeed, He alone has it in a perfectly comprehensive way. And
He has it in the highest degree inasmuch as it is also had by
men in their own way, although it is not had by them as a
human possession, but as something borrowed from Him.
65. From these considerations he draws the further conclu­
sion that all other sciences are more necessary than this science
for use in practical life, for these sciences are sought least of
all for themselves. But none of the other sciences can be more
excellent than this one.

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Philosophy of St. Thomas: Metaphysics

II. THE “SUBJECT” OF METAPHYSICS

(In IV Metaph. lect. 4, nos. 529-547)
At the beginning of Book r Aristotle sets forth the object
—in the logic of science, the “subject”—of metaphysics:
being as being, and its basic properties; hence our interest in
the passage and its commentary, interest all the greater be­
cause to determine the object of metaphysics is at the same
time to consider the analogical structure of being. Only the
analogical notion of being can embrace being in its uni­
versality together with its diversity. Aristotle, it will be seen,
speaks only of the analogy of attribution, where substance
is the primary term or analogue. St. Thomas, though not in
the Commentary, views all things in relation to God, and
thus carries his thought beyond Aristotle. For all that,
however, his remarks herewith provide one of the basic
sources of his own teaching on the analogy of being. (Col­
late with supra, chapter 2, “Being,” p. 35).
A. The “subject” of metaphysics is being, as being

a) 529. First of all, Aristotle says there is a science which
studies being as being, as its subject, and studies also “the at­
tributes which necessarily belong to being,” i.e. its proper ac­
cidents.
530. He says “as being” because the other sciences, which
deal with particular beings, do indeed consider being (for all
the subjects of the sciences are beings), yet they do not consider
being as being, but as some particular kind of being, for example,
number or line or fire or the like.
531. He also says “and the attributes which necessarily be­

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245
long to being,” and not just those which belong to being, in
order to show that it is not the business of this science to con­
sider those attributes which belong accidentally to its subject,
but only those which belong to it necessarily. For geometry does
not consider whether a triangle is of bronze or of wood, but
only considers it in an absolute sense according as it has three
angles equal to two right angles. Hence a science of this kind,
whose subject is being, must not consider all the attributes
which belong accidentally to being, . . . Now the necessity of
this science, which considers being and its proper accidents,
is evident from this, that such things should not remain un­
known since the knowledge of other things depends on them,
just as the knowledge of proper objects depends on that of
common objects.
b) 532. Aristotle then shows that this science is not one
of the particular sciences, and he uses the following argument.
No particular science considers universal being as such, but
only some part of it separated from the others; and about this
part it studies the proper accidents. For example, the mathe­
matical sciences study one kind of being, quantitative being.
But the common science considers universal being as being, and
therefore it is not the same as any of the particular sciences.
533...........................................................................................
B. Metaphysics considers both substance
and the accidents

534. Here Aristotle uses this argument: those things which
have one term predicated of them in common, not univocally
but analogously, belong to the consideration of one science. But
the term being is thus predicated of all beings. Therefore all
beings, i.e. both substances and accidents, belong to the con­
sideration of one science which considers being as being.

Philosophy of St. Thomas: Metaphysics
Proof of the minor through the analogy of being
246

535. Aristotle accordingly says, first, that the term being, or
what is, has several meanings. But it must be noted that a term
is predicated of different things in various senses. Sometimes it
is predicated of them according to a meaning which is entirely
the same, and then it is said to be predicated of them univocally,
as animal is predicated of a horse and of an ox. Sometimes it
is predicated of them according to meanings which are entirely
different, and then it is said to be predicated of them equiv­
ocally, as dog is predicated of a star and of an animal. And some­
times it is predicated of them according to meanings which
are partly different and partly not (different inasmuch as they
imply different relationships, and the same inasmuch as these
different relationships are referred to one and the same thing),
and then it is said “to be predicated analogously,” i.e. propor­
tionally, according as each one by its own relationsnip is re­
ferred to that one same thing.
536. It must also be noted that the one thing to which the
different relationships are referred in the case of analogical
things is numerically one and not just one in meaning, which
is the kind of oneness designated by a univocal term. Hence
he says that, although the term being has several senses, still
it is not predicated equivocally but in reference to one thing;
not to one thing which is one merely in meaning, but to one
which is one as a single definite nature. This is evident in the
examples given in the text.
537. First, he gives the example of many things being related
to one thing as an end. This is clear in the case of the term
healthy or healthful. For the term healthy is not predicated
univocally of food, medicine, urine, and an animal; because
the concept healthy as applied to food means something that
preserves health; and as applied to medicine it means something
that causes health; and as applied to urine it means something

Texts
that is a sign of health; and as applied to an animal it means
something that is the recipient or subject of health. Hence every
use of the term healthy refers to one and the same health; for
it is the same health which the animal receives, which urine is
a sign of, which medicine causes, and which food preserves.
538. Aristotle then gives an example of many things being
related to one thing as an efficient principle [the example of
“medical”]. . . .
539. And just as the above-mentioned terms have many
senses, so also does the term being. Yet every being is called
such in relation to one first thing, and this first thing is not an
end or an efficient cause, as is the case in the foregoing ex­
amples, but a subject. For some things are called beings, or are
said to be, because they have being of themselves [per se], as
substances, which are called beings in the primary and proper
sense. Others are called beings because they are affections or
properties of substances, as the proper accidents of any sub­
stance. Others are called beings because they are processes to­
ward substance, as generation and motion. And others are called
beings because they are corruptions of substances; for corruption
is the process toward nonbeing just as generation is the process
toward substance. And since corruption terminates in privation
just as generation terminates in form, the very privations of
substantial forms are fittingly called beings. Again, certain quali­
ties or certain accidents are called beings because they are pro­
ductive or generative principles of substances or of those things
which are related to substance according to one of the foregoing
relationships or any other relationship. And similarly the nega­
tions of those things which are related to substances, or even of
substance itself, are also called beings. Hence we say that nonbeing is nonbeing. But this would not be possible unless a
negation possessed being in some way.
540. But it must be noted that the above-mentioned modes
of being can be reduced to four. For one of them, which is the

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Philosophy of St. Thomas: Metaphysics
most imperfect, i.e. negation and privation, exists only in the
mind. We say that these exist in the mind because the mind
busies itself with them as kinds of being, while it affirms or
denies something about them. In what respect negation and
privation differ will be treated below [nos. 564 ff.].
541. There is another mode of being inasmuch as generation
and corruption are called beings, and this mode by reason of
its imperfection comes close to the one given above. For gen­
eration and corruption have some admixture of privation and
negation, because motion is an imperfect kind of actuality, as
is stated in the Physics [III, 2, 201 b 31].
542. The third mode of being admits of no admixture of
nonbeing, yet it is still an imperfect kind of being, because it
does not exist of itself but in something else, for example, quali­
ties and quantities and the properties of substances.
543. The fourth mode of being is the one which is most
perfect, namely, what has being in reality without any admix­
ture of privation, and has firm and solid being inasmuch as it
exists of itself [per se]. This is the mode of being which sub­
stances have. Now all the others are reduced to this as the pri­
mary and principal mode of being; for qualities and quantities
are said to be inasmuch as they exist in substances; and motions
and generations are said to be inasmuch as they are processes
tending toward substance or toward some of the foregoing; and
negations and privations are said to be inasmuch as they re­
moved some part of the preceding three.
544 ..........................................................................................
545 ..........................................................................................
C. Metaphysics treats principally of substance

546. Aristotle then shows that this science, even though it
considers all beings, is chiefly concerned with substances. He
uses the following argument. Every science which deals with
many things that are referred to one primary thing is properly

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249
and principally concerned with that primary thing on which
other things depend for their being and from which they derive
their name; and this is true in every case. But substance is the
primary kind of being. Hence the philosopher who considers all
beings ought to consider primarily and chiefly the principles and
causes of substances. Therefore his consideration extends pri­
marily and chiefly to substances.
III. THE STUDY OF THE ONE
PERTAINS TO METAPHYSICS

(In IV Metaph. lect. 2, nos. 550-553, 559-560)
The lesson referred to here completes the preceding. If
metaphysics studies being it must study the one for the very
basic reason that between being and one the distinction is
not real but only of reason. Objectively, one and being are
the same thing. The paragraphs cited are of interest for the
general theory of transcendentals as well as, in particular,
for the relation of one to being. Clearly brought out, more­
over, is the distinction between the transcendental one and
the arithmetical (or predicamental) unit, the principle of
number. (Collate with supra, “The Transcendentals in
Particular,” p. 128).
A. One and being are really identical

but differ conceptually

550. That one and being are really identical Aristotle proves
by two arguments [of which the first runs as follows]. Any two
things which when added to some third thing cause no differ­
ence are wholly the same. But when one and being are added to
man or to anything at all, they cause no difference. Therefore
they are wholly the same. The truth of the minor premise is evi­
dent; for it is the same thing to say “man” and “one man.” And

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Philosophy of St. Thomas: Metaphysics
similarly it is the same thing to say “human being” and “the
thing that is man”; and nothing different is expressed when in
speaking we repeat the terms, saying, “This is a human being, a
man, and one man.” He proves this as follows.
551. It is the same thing for man and the thing that is man
to be generated and corrupted. This is evident from the fact
that generation is a process toward being, and corruption a
change from being to nonbeing. Hence a man is never gener­
ated without a human being being generated, nor is a man ever
corrupted without a human being being corrupted. Now, those
things which are generated and corrupted together are them­
selves one and the same.
552. And just as it has been said that being and man are not
separated either in generation or in corruption, so too this is evi­
dent of what is one; for when a man is generated, one man is
generated, and when a man is corrupted, one man is also cor­
rupted. It is clear, then, that the apposition of these [i.e. of
“one” or “being” to man] expresses the same thing, and that
just because the term one or being is added to man it is not to
be understood that some nature is added to man. And from this
it is clearly apparent that unity [unum] does not differ from
being, because any two things which are identical with some
third thing are identical with each other.
553. It is also evident from the foregoing argument that unity
and being are the same numerically [in re] but differ concep­
tually; for if they did not differ conceptually, they would be
wholly synonymous, and then it would be nonsense to say “a
human being” and “one man”. . . .

B. The transcendental one and one,
principle of number
559. Nor does it seem to be true that the one or unity which
is interchangeable with being and that which is the principle of

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251
number are the same; for nothing that pertains to some special
class of being seems to be characteristic of all beings. Hence the
unity which is limited to a special class of being—discrete quan­
tity—does not seem to be interchangeable with universal being.
For, if unity is a proper and essential accident of being, it must
be caused by the principles of being as being, just as any proper
accident is caused by the principles of its subject. But it is not
reasonable that something having a particular mode of being
should be adequately accounted for by the common principles
of being as being. It cannot be true, then, that something which
belongs to a definite genus and species is an accident of every
being.
560. Therefore the kind of unity which is the principle of
number differs from that which is interchangeable with being;
for the unity which is interchangeable with being signifies being
itself, adding to it the notion of undividedness, which, since it
is a negation or a privation, does not posit any reality added to
being. Thus, this unity differs from being in no way numerically
but only conceptually; for a negation or a privation is not a real
being but a being of reason, as has been stated [no. 540]. How­
ever, the kind of unity which is the principle of number adds to
substance the note of a measure, which is a special property of
quantity and is found first in the unit. And it is described as the
privation or negation of division which pertains to continuous
quantity; for number is produced by dividing the continuous.
Hence number belongs to mathematical science, whose subject
cannot exist apart from sensible matter but can be considered
apart from sensible matter. But this would not be so if the kind
of unity which is the principle of number were separate from
matter in being and existed among the immaterial substances,
as is true of the kind of unity which is interchangeable with
being.

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Philosophy of St. Thomas: Metaphysics

IV. CONCERNING THE FIRST PRINCIPLE
OF DEMONSTRATION

(In IV Metaph. lect. 6, nos. 597-608)
The critical study of first principles, truths on which
every demonstration ultimately rests, has become standard
procedure in philosophy. To Aristotle, it seems, must go the
credit for having introduced this criteriological chapter into
metaphysics, as well as for having brought the discussion
round to the principle which, for all practical purposes,
would thenceforth be honored as the very law of under­
standing, the principle of noncontradiction. We have
selected the more significant paragraphs of Lesson 6 in St.
Thomas’ Commentary on Metaphysics, Book IV, para­
graphs which form the natural introduction to the question
at hand. (Collate with supra, “First Principles,” p. 106).
A. Conditions which the most certain principle

must meet
597. Aristotle lays down three conditions for this principle.
The first is that no one can make a mistake or be in error regard­
ing it. And this is evident because, since men make mistakes
only about those things which they do not know, then that
principle about which no one can be mistaken must be the one
which is best known.
598. The second condition is that it must “not be hypotheti­
cal,” i.e. it must not be held as a supposition, as those things
which are maintained through some kind of common agree­
ment. . . . And this is true, because whatever is necessary for
understanding anything at all about being “is not hypothetical,”
i.e. it is not a supposition but must be self-evident. And this is

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253
true because whatever is necessary for understanding anything
at all must be known by anyone who knows other things.
599. The third condition is that it be not acquired by demon­
stration or by any similar method, but that it come, in a sense,
by nature to the one having it inasmuch as it is naturally known
and not acquired. For first principles become known through
the natural light of the agent intellect, and they are not acquired
by any process of reasoning but by having their terms become
known. This comes about by reason of the fact that memory is
derived from sensible things, experience from memory, and
knowledge of those terms from experience. And when they are
known, common propositions of this kind, which are the prin­
ciples of the arts and sciences, become known. Hence it is evi­
dent that the most certain or firmest principle should be such
that there can be no error regarding it; that it be not hypotheti­
cal; and that it come naturally to the one having it.

B. Which principle meets these conditions?
600. Then he indicates the principle that meets the above
conditions. And he says it is this principle, as the one which is
firmest, namely: that it is impossible for the same attribute both
to belong and not belong to the same subject at the same time.
And it is necessary to add “in the same respect”; and any other
qualifications that have to be given regarding this principle “to
meet dialectical difficulties” must be laid down, since without
these qualifications there would seem to be a contradiction when
there is none.
601. That this principle must meet the conditions given above
he shows as follows: it is impossible for anyone to think, or
hold as an opinion, that the same thing both is and is not at the
same time, although some believe that Heraclitus was of this
opinion. But while it is true that Heraclitus spoke in this way,
he could not think that this is true; for it is not necessary that

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everything that a person says he should accept mentally or hold
as an opinion.
602. But if one were to say that it is possible for someone to
think that the same thing both is and is not at the same time,
this absurd consequence follows: contraries could belong to the
same subject at the same time. And this is clear from a wellknown teaching in logic. For it is shown at the end of the
Perihermeneas [De Interpretatione, 14, 23 b 23] that contrary
opinions are not those which have to do with contraries but
those which have to do with contradictories, properly speaking.
For when one person thinks that Socrates is white and another
thinks that he is black, these are not contrary opinions in the
primary and proper sense; but contrary opinions are had when
one person thinks that Socrates is white and another thinks that
he is not white.
603. Therefore, if someone were to think that two contradic­
tories are true at the same time by thinking that the same thing
both is and is not at the same time, he will have contrary opin­
ions at the same time; and thus contraries will belong to the
same thing at the same time. But this is impossible. It is impos­
sible, then, for anyone to be mistaken in his own mind about
these things and to think that the same thing both is and is not
at the same time. And it is for this reason that all demonstrations
reduce their propositions to this proposition as the ultimate opin­
ion common to all; for this proposition is by nature the starting
point and “the axiom of all axioms.”
604. The other two conditions are therefore evident, because,
in so far as those making demonstrations reduce all their argu­
ments to this principle as the ultimate one by referring them to
it, evidently this principle is not based on an assumption. In­
deed, in so far as it is by nature a starting point, it clearly comes
as by nature to the one having it and is not acquired by his
own effort.

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605. Now for the purpose of making this evident it must be
noted that, since the intellect has two operations, one by which
it knows quiddities, which is called the understanding of indi­
visibles, and another by which it combines and separates, there
is something first in both operations. In the first operation the
first thing that the intellect conceives is being, and in this opera­
tion nothing else can be conceived unless being is understood.
And because this principle—it is impossible for a thing both to
be and not be at the same time—depends on the understanding
of being (just as the principle, every whole is greater than one
of its parts, depends on the understanding of whole and part),
therefore this principle is by nature also the first in the second
operation of the intellect, i.e. in the act of combining and sepa­
rating. And no one can understand anything by this second
intellectual operation unless this principle is understood. For
just as a whole and its parts are understood only by understand­
ing being, in a similar way the principle that every whole is
greater than one of its parts is understood only if the aforesaid
firmest or most certain principle is understood.
C. Errors committed in regard to this principle

a) Error of those who deny this principle (no. 606)
b) Error of those who want to demonstrate it (no. 607). There
are some, says Aristotle, who deem it fitting, i.e. who wish to
demonstrate this principle; and they do this “through want of
education,” i.e. through lack of learning or instruction. For there
is want of education when a man does not know what to seek
demonstration for and what not; for not all things can be
demonstrated. If all things were demonstrable, then, since a
thing is not demonstrated through itself but through something
else, demonstrations would either be circular (although this can­
not be true, because then the same thing would be both better
known and less well known, as is clear from Book I of the

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Posterior Analytics [I, 2, 72 a 30; 3, 72 b 5 ff.]), or they would
have to proceed to infinity. But if there were an infinite regress
in demonstrations, demonstration would be impossible, because
the conclusion of any demonstration is made certain by reducing
it to the first principle of demonstration. But this would not be
the case if demonstration proceeded to infinity. It is clear, then,
that not all things are demonstrable. And if some things are not
demonstrable, these men cannot say that any principle is more
indemonstrable than the above-mentioned one.
608. Aristotle then shows that the above-mentioned principle
can be demonstrated in a certain respect. He says that it may
be demonstrated by disproof. In Greek the word is ÈXc/ktikus,
which is better translated by refutation, for an ÈAeyx°« is a syl­
logism that establishes the contradictory of a proposition, and so
is introduced to refute some false position. And on these grounds
it can be shown that it is impossible for the same thing both to
be and not be. But this kind of argument can be employed only
if the one who denies that principle because of some doubt or
other “says something,” i.e. if he signifies something by a word.
But if he says nothing, it is ridiculous to look for a reason
against one who does not make use of reason in speaking; for in
this dispute anyone who signifies nothing will be like a plant,
since even brute animals signify something by certain signs.
V. PRINCIPAL MODES OF BEING

(In V Metaph. lect. 9, nos. 885-886, 889-892, 895-897)
Aristotle sets forth the principal modes of being on
numerous occasions. The classification presented in the
above reference is notable for its completeness and precise­
ness. Being is first of all divided into essential being (ens
per se) and accidental being (ens per accidens), the latter of
which is not to be confused with predicamental accident.
Essential being, in turn, bears the following subdivisions:

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i) the predicaments or categories, 2) the being which signi­
fies the truth of a proposition (ens verum), and 3) the being
of act and potency. Only predicamental being, however, and
the being of act and potency are real; hence only these,
properly speaking, pertain to the object of metaphysics.
Accidental being, which has no proper cause, and being as
the truth of a proposition (hence as existing in the mind
only) do not, in all strictness, come under its object.
A. EssenizuZ being and accidental being
(ens per se, ens per accidens)

885. Aristotle observes that things are said to be both essen­
tially and accidentally. It should be noted, however, that this
division of being is not the same as that whereby being is di­
vided into substance and accident. This is clear from the fact
that he later divides essential being into the ten predicaments,
nine of which belong to the class of accident [no. 880]. Hence
being is divided into substance and accident in so far as it is
considered in an absolute sense; for example, whiteness consid­
ered in itself is called an accident, and man a substance. But
accidental being, in the sense in which it is taken here, must be
understood by comparing an accident with a substance; and this
comparison is signified by the term is when, for example, it is
said that the man is white. Hence this totality, “the man is
white,” is an accidental being. It is clear, then, that the division
of being into essential being and accidental being is based on
the fact that one thing is predicated of another either essentially
or accidentally. But the division of being into substance and ac­
cident is based on the fact that a thing is in its own nature
either a substance or an accident.
886. Aristotle then states the various senses in which a thing
is said to be accidentally. He says that this occurs in three ways :
first, when an accident is predicated of an accident, as when it

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is said that someone just is musical; second, when an accident
is predicated of a subject, as when it is said that the man is
musical; and third, when a subject is predicated of an accident,
as when it is said that the musician is a man. . ..
B. The modes of essential being (ens per se)

a) Division, by the ten predicaments, of being which lies
outside the mind (no. 889). Aristotle explains here that all those
things which signify the figures of predication are said to be
essentially. For it must be noted that being cannot be nanowed
down to some definite thing in the way in which a genus is
narrowed down to a species by means of differences. For since a
difference does not participate in a genus, it lies outside the es­
sence of a genus. But there could be nothing outside the essence
of being which could constitute a particular species of being by
adding to being; for what is outside of being is nothing, and this
cannot be a difference. Hence in Book III of this work [B, 3, 998
b 23 ff.] the Philosopher proved that being cannot be a genus.
890. Being must then be narrowed down to diverse genera on
the basis of a different mode of predication, which flows from a
different mode of being; for “being is signified,” i.e. something
is signified to be “in just as many ways” (or in as many senses)
as we can make predications. And for this reason the classes
into which being is first divided are called predicaments, because
they are distinguished on the basis of different ways of predicat­
ing. Therefore, since some predicates signify “what” (i.e. sub­
stance), some, “of what kind” (quality), some, “how much”
(quantity), and so on, there must then be a mode of being
corresponding to each type of predication. For example, when
it is said that a man is an animal, is signifies substance; and
when it is said that a man is white, is signifies quality; and so on.
891-892. Text relative to the division into ten predicaments
[Cf. supra, p. 170t., for the text.]

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25g
b) Being which signifies the composition of a proposition
(no. 895). Aristotle then gives another sense in which the term
being is used, according as “being” and “is” signify the composi­
tion of a proposition, which the intellect makes when it com­
bines and separates. Hence he says that being signifies the truth
of a thing, or as another translation better expresses it, being
signifies that some statement is true. Tirus the truth of a thing
can be said to determine the truth of a proposition after the
manner of a cause; for by reason of the fact that a thing is or is
not, an assertion [oratio] is true or false. . . .
896. Now it must be noted that this second way in which
being is used is related to the first as an effect is to a cause. For
from the fact that something is in reality it follows that there is
truth and falsity in a proposition, and the intellect signifies this
by the term is, taken as a verb copula. But since the intellect
considers as a kind of being something which in itself is a nonbeing, such as a negation and the like, therefore sometimes be­
ing is predicated of something in this second way and not in the
first. For blindness is said to be in the second way on the grounds
that the proposition in which something is said to be blind is
true. However, it is not said to be true in the first way; for blind­
ness does not have any being in reality but is rather a privation
of some being. Now it is accidental to a thing that an attribute
should be affirmed of it truly in thought or in word, for reality
is not referred to knowledge but the reverse. But the act of being
which each thing has in its own nature is substantial; and there­
fore when it is said that Socrates is, if the is be taken in the first
way, it belongs to the class of substantial predicates; for being
is a higher predicate with reference to any particular being, as
animal with reference to man. But if it be taken in the second
way [as verb ccr ala], it belongs to the class of accidental predi­
cates.
c) Division of being into act and potency (no. 897). Aristotle

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then gives the division of being into the actual and the poten­
tial. He says that to be and being signify something which is
expressible or utterable potentially or actually. For in the case
of all the foregoing terms which signify the ten predicaments,
something is said to be actually and something potentially; and
from this it follows that each predicament is divided by actuality
and potentiality. And just as in the case of things which are out­
side the mind some are said to be actually and some potentially,
so also is this true in the case of the mind’s activities, and in
that of privations, which are only conceptual beings. For one is
said to know both because he is capable of using scientific
knowledge and because he is using it; and similarly a thing is
said to be at rest both because rest belongs to it already and
because it is capable of being at rest. And this is true not only
of accidents but also of substances. For “Mercury,” we say, i.e.
the image of Mercury is present potentially in the stone; and
half of a line is present potentially in a line, for every part of a
continuum is potentially in the whole. And line is included in
the class of substances according to the opinion of those who
hold that the objects of mathematics are substances—an opin­
ion which he has not yet disproved. Also grain, when it is not
yet ripe, as when it is still in blade, is said to be potentially. Just
when, however, something is potential and when it is no longer
such, this is established elsewhere, namely, in Book IX of this
work [®, 7,1048 b 35 ft.]

VI. METAPHYSICS AS THE SCIENCE
OF SUBSTANCE

(In VII Metaph. lect. 1, nos. 1248-1255, 1257-1259)
Having eliminated (in Book E) from the object of meta­
physics both accidental being (ens per accidens), which has
not a determinate cause, and being as truth, which exists as

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such in the intellect only, Aristotle turns his attention to
the study of essential being (ens per se~). His first division
here is, as we have seen (Text V), that of the ten predica­
ments. For all practical purposes, however, the study of
metaphysics is, for him, the study of substance. At the
beginning of Book Z Aristotle explains why it must be so,
and in the course of the discussion gives some interesting
clarifications on substance and accidents, and the relation
of these two modes of being to each other. Special notice
should be given that in this context, as for that matter in
many others, the designations quid, quale, and quantum
have a meaning that is both technical and precise, “quid”
corresponding to substance, “quale” to quality, and “quan­
tum” to quantity. (Collate with supra, “Substance,” p. 154).
A. Substance is first being

1248. In proof of this contention Aristotle argues as follows.
In every class of things that which exists of itself and is a being
in an unqualified sense is prior to that which exists by reason
of something else and is a being in a qualified sense. But sub­
stance is a being in an unqualified sense and exists of itself
[per se], whereas all classes of beings other than substance are
beings in a qualified sense and exist by reason of substance.
Therefore substance is the primary kind of being.
1249. Aristotle then elucidates the minor premise, in two
ways. First, by considering the way in which we speak, or make
predications. It is evident, he says, that substance is the primary
kind of being from the fact that when we state of what sort a
thing is we say that it is either good or evil; for this signifies
quality, which differs from substance and quantity. Three cubits
long, however, signifies quantity, and man signifies substance.
Therefore when we state of what sort a thing is, we do not say

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that it is three cubits long or a man. And when we state what
a thing is, we do not say that it is white or hot, which signify
quality, or three cubits long, which signifies quantity, but we say
that it is a man or a god, which signifies substance.
1250. From this it is clear that terms signifying substance
express what a thing is in an unqualified sense, whereas those
signifying quality do not express what a thing is in an unquali­
fied sense, but what sort of thing it is. The same is true of
quantity and the other genera.
1251. And thus it is also clear that substance itself is said to
be a being of itself [ratione suiipsius], because terms which sim­
ply signify substance designate what this thing is. But other
classes of things are said to be beings, not because they have a
quiddity of themselves (as though they were beings of them­
selves, since they do not express what a thing is an an unquali­
fied sense), but because “they belong to such a being,” i.e.
because they have some connection with substance, which is a
being of itself. For they do not signify quiddity, since some of
them are clearly qualities of such a being, i.e. of substance, oth­
ers quantities, others affections, or something of the sort sig­
nified by the other genera.
1252-1255. Proof by an example.
B. In what respects substance is first being,

1257. Here Aristotle shows in what respects substance is said
to be first. Since the term first is used in several senses, as has
been explained in Book V [A, 11, 1018 b 10 ff.], substance is of
all beings the first in three respects : in the order of knowing, in
definition, and in time. He proves that it is first in time by this
argument: none of the other predicaments is capable of existing
apart from substance, but substance alone is capable of existing
apart from the others; for no accident is found without a sub­

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stance, but some substance is found without an accident. Thus
it is clear that an accident does not exist whenever a substance
does, but the reverse is true; and for this reason substance is
prior in time.
1258. It is also evident that it is first in definition, because in
the definition of any accident it is necessary to include the
definition of substance; for just as nose is given in the definition
of snub, so too the proper subject of any accident is given in
the definition of that accident. Hence just as animal is prior to
man in definition, because the definition of animal is given in
that of man, in a similar fashion substance is prior to accidents
in definition.
1259. It is evident, too, that substance is first in the order of
knowing, for that is first in the order of knowing which is better
known and explains a thing better. Now each thing is better
known when its substance is known than when its quality or
quantity is known; for we think we know each thing best when
we know what it is, a man (say) or fire, rather than when we
know of what sort it is or how much it is or where it is or when
we know it according to any of the other categories. For this
reason too we think that we know each of the things contained
in the predicaments of accidents when we know what each is;
for example, when we know what being “this sort” of thing is
we know quality; and when we know what being “how much”
is we know quantity. For just as the other predicaments have
being only in so far as they inhere in a substance, in a similar
way they can be known only in so far as they share to some ex­
tent in the mode according to which substance is known, and
this is to know the whatness of a thing.
VII. POTENCY AND ACT
All of Book © (Book IX, in the Commentary of St.
Thomas) is given to act and potency, the second of the three

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main divisions under essential being (ens per se). True, the
division of being by act and potency had already been
introduced in the Physics, to serve in the definition of
motion, a limited application of the division. In the Meta­
physics, on the other hand, act and potency are studied in
their universality, i.e. as pertaining, one or both, to all
beings, to those which are immobile (unchanging) as well
as to those which are subject to motion (change of any
kind). The portions from the Commentary which follow
are basic to the division in question; in them St. Thomas
spells out the meaning of act and potency and declares
their principal modes. Worth noting is the procedure by
inductive analogy. It is almost always by this procedure,
and not by abstract analysis, that Aristotle arrives at his
definitions; and the same is to be said for his disciple St.
Thomas. (Collate with supra, chapter 6, “Act and Potency,”
p. 183).
A. Explication of potency

(In IX Metaph. lect. 1, nos. 1773-1780)

1773. Aristotle then says it has been shown elsewhere, i.e. in
Book V of this work [A, 12], that “potency” and “to be able”
have a multiplicity of meaning. But in some cases this multi­
plicity is a multiplicity of equivocation, and in others it is a
multiplicity of analogy. For some things are said to be capable
or incapable [possibilia vel impossibilia] because they have some
principle within themselves, and this refers to those senses in
which all potencies are said to be potencies not equivocally but
analogously. But other things are not said to be capable or able
because of some principle which they have within themselves;
and in their case the term potency is used equivocally.

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1774. Therefore, with regard to those senses in which the
term potency is used equivocally, he says that these must be
dismissed for the present. For the term potency is referred to
some things, not because of some principle which they have, but
in a figurative sense, as is done in geometry; for the square of a
line is called its power [potentia], and a line is said to be capable
of becoming its square. . . .
1775. [The figurative meaning of potency in logic]
1776. Passing over these senses of potency, then, we must
consider those potencies which are reduced to one species, be­
cause each of these is a principle. And all potencies spoken of
in this sense are reduced to some principle from which all the
others derive their meaning; and this is an active principle,
which is the source of change in some other thing in so far as it
is other. He says this because it is possible for an active principle
to be at the same time in the mobile or patient, as when some­
thing moves itself; however, it is not mover and moved, or agent
and patient, in the same respect. Hence the principle designated
as active potency is said to be a principle of change in some
other thing in so far as it is other; for, even though an active
principle can be found in the same thing as a passive principle,
this still does not happen in so far as it is the same, but in so far
as it is other.
1777. That the other potencies are reduced to this principle
which is called active potency is evident; for in one sense passive
potency means the principle by which one thing is moved by
some other thing in so far as it is other. He says this because,
even if the same thing might be acted upon by itself, this does
not happen in so far as it is the same, but in so far as it is other.
Now this potency is reduced to a first active potency, because
when anything undergoes change this is caused by an agent. . . .
1778. In another sense potency means a certain state of in­
susceptibility [habitus impassibilitatis] “to change for the

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worse,” i.e. a disposition whereby a thing is such that it cannot
undergo change for the worse; which is to say it cannot undergo
corruption as a result of some other thing “in so far as it is
other,” namely, by a principle of change which is an active
principle.
1779. Now it is evident that both of these senses of potency
imply something within us which is referred to the undergoing
of a change. For in the one sense the term designates a principle
by reason of which someone cannot be acted upon; and in the
other sense it designates a principle by reason of which someone
can be acted upon. Hence, since the state of being acted upon
depends on action, the definition “of the primary kind of po­
tency,” namely active potency, must be given in the definition
of both senses of potency. Thus these two potencies are reduced
to the first, i.e. to active potency, as to something prior.
1780. Again, in another sense potencies are spoken of not only
in relation to acting and being acted upon but in relation to
what is done well in both instances. For example, we say that
someone is capable of walking, not because he can walk in any
way at all, but because he can walk well; and in an opposite
sense we say of one who limps that he cannot walk. Similarly,
we say that wood is capable of being burned because it can be
burned easily; but we say that green wood is incapable of being
burned because it cannot be burned easily. Hence it is clear that
in the definitions of those potencies which are described as
potencies for acting and being acted upon well, there are in­
cluded the concepts of those primary potencies which were de­
scribed as potencies for acting and being acted upon without
qualification; for example, to act is included in to act well, and
to be acted upon is included in to be acted upon well. Hence
it is obvious that all of these senses of potency are reduced to
one primary sense, namely to active potency; and therefore it
is also evident that this multiplicity is not a multiplicity of
equivocation but of analogy.

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Texts
B. Explication of act

(In IX Metaph. lect. 5, nos. 1825-1831)
1825. Aristotle then shows what actuality (or act) is. He says
that a thing is actual when it exists but not in the way it exists
when it is potential. For we say that the image of Mercury is in
the wood potentially and not actually before the wood is carved;
but once it has been carved the image of Mercury is then said
to be in the wood actually. And in the same way we say that any
part of a continuous whole is in that whole, because any part
(for example, the middle one) is present potentially inasmuch
as it is possible for it to be separated from the whole by dividing
the whole; but after the whole has been divided, that part will
then be present actually. The same thing is true of one who has
a science and is not speculating, for he is capable of speculating
even when he is not doing so; but to be speculating or contem­
plating is to be in a state of actuality.
1826. And here he answers an implied question: for someone
could ask him to explain what actuality is by giving its defini­
tion. Aristotle answers that it is possible to show what we mean
by actuality inductively, i.e. by adducing individual examples,
“and we should not look for the boundaries of everything,” i.e.
the definition. For the first simple notions cannot be defined,
since an infinite regress in definitions is impossible. But actuality
is one of those first simple notions. Hence it cannot be defined.
1827. But we can see, he says, what actuality is by means of
the proportion existing between two things. For example, we
may take the proportion of one who is building to one capable
of building; and of one who is awake to one asleep; and of one
who sees to one whose eyes are closed although he has the power
of sight; and “of that which is separated out of matter,” i.e. of
what is formed by means of the operation of art or of nature and
thus is separated out of unformed matter, to what is not sepa-

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rated out of unformed matter. And similarly we may take the
proportion of what has been prepared to what has not been
prepared, or of what has been worked on to what has not been
worked on. But in each of these opposed pairs one member will
be actual and the other potential. And thus by proceeding from
particular cases we can come to an understanding, in a propor­
tional way, of what actuality and potentiality are.
1828. Aristotle then shows that the term actuality is used in
different senses; and he gives two different senses in which it is
used, a) First, actuality means action, or operation. And with a
view to introducing the different senses of actuality he says,
first, that we do not say that all things are actual in the same
way but in different ways; and this difference can be considered
according to different proportions. For a proportion can be
taken as meaning that just as one thing is in another, so a third
is in a fourth; for example, just as sight is in the eye, so hearing
is in the ear. And the relation of substance (i.e. form) to matter
is taken according to this kind of proportion; for form is said to
be in matter.
1829. There is another meaning of proportion inasmuch as
we say that, just as this is related to that, so another thing is
related to something else; for example, just as the power of
sight is related to the act of seeing, so the power of hearing is
related to the act of hearing. And the relation of motion to mo­
tive power or of any operation to an operative potency is taken
according to this kind of proportion.
1830. b) Secondly, he gives the other sense in which the word
actuality is used. He says that the infinite and the empty or the
void, and all things of this kind, are said to exist potentially
and actually in a different sense from many other beings; for
example, what sees and what walks and what is visible. For it
pertains to things of this kind that they sometimes exist in an
unqualified sense either only potentially or only actually; for

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example, the visible is only actual when it is seen, and it is only
potential when it is capable of being seen but is not being seen.
1831. But the infinite is not said to exist potentially in the
sense that it may sometimes have separate actual existence
alone; rather, actuality and potentiality in the infinite are dis­
tinguished only in thought and in knowledge. For example, in
the case of the infinite in the sense of the infinitely divisible,
actuality and potentiality are said to exist at the same time,
because the capacity of the infinite for being divided never
comes to an end; for when it is actually divided it is still poten­
tially further divisible. However, it is never actually separated
from potentiality in such a way that the whole is sometimes
actually divided and is incapable of any further division. And
the same thing is true of the void; for it is possible for a place to
be emptied of a particular body, but not so as to be a complete
void, for it continues to be filled by another body; and thus in
the void potentiality always continues to be joined to actuality.
The same is also true of motion and time and other things of
this kind which do not have complete being.

VIII. GOD IS LIFE

(In XII Metaph. lect. 8, no. 2544)
Book A marks the climax of the Metaphysics. To the
question, his own, whether there are separate substances,
Aristotle replies by establishing the existence of a first un­
moved mover, whose nature he then proceeds to expound.
St. Thomas, to be sure, when pursuing the subject of God
on his own, betters Aristotle by far, and thus we do not go
to the Commentary on the Metaphysics for his clearest and
closest presentations to the purpose. Just the same, Aris­
totle’s insights in the matter will have been truly profound
and penetrating, as witness his remarks concerning God’s

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life, here cited through the Commentary of St. Thomas.
And with the following passage we come to the last of our
excerpts from Aristotle the metaphysician as seen through
the eyes of his pre-eminent disciple.
2544. Aristotle says that God is life itself, and proves it as
follows. “Intellectual activity,” i.e. understanding [intelligere]
is a kind of life; and it is the most perfect kind of life that there
is. For according to what has been shown, actuality is more per­
fect than potentiality; and therefore an intellect which is actu­
ally understanding leads a more perfect life than one which is
potentially understanding, just as being awake is more perfect
than being asleep. But the first being, God, is actuality itself;
for His intellect is His intellectual activity; otherwise He would
be related to His intellectual activity as potentiality to actuality.
Moreover, it has been shown that His substance is actuality.
Thus it follows that the very substance of God is life; and that
His actuality is His life, and that it is the life which is best and
eternal and subsists of itself. This is why the popular opinion
holds that God is an animal which is eternal and best; for
around us life is clearly apparent only in animals, and therefore
God is called an animal because life belongs to Him. Hence,
from what has been said it is evident that life and continuous
and eternal duration belong to God, because God is identical
with His own eternal life; for He and His life are not different.
IX. ONE AS PRINCIPLE OF NUMBER AND
ONE AS TRANSCENDENTAL

(De Potentia, q.9, a.7)

In the Quaestiones Disputatae of St. Thomas there are
several presentations, all of them more or less ample and
incisive, concerning the transcendentals. One such passage
(De Verit. q.i, a.i) we had occasion to paraphrase in the

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271
fore part of our study (cf. supra, p. 124 f). In this pre-eminent
text the doctrine of transcendentals is treated in its entirety.
Given below, on the other hand, is an excerpt from De
Potentia, also made use of earlier (cf. supra, p. 129); what it
presents is St. Thomas’ concluding remarks on the meaning,
the twofold meaning of the notion one. St. Thomas, it will
be seen, is above all concerned with dispelling the confusion
that comes about by not distinguishing between one as
principle of number and one as transcendental. (Collate
with supra, “The Transcendentals in Particular,” p. 128).
Accordingly, the above opinions were based on the supposi­
tion that the one which is convertible with being is the same
with that which is the principle of number, and that there is no
plurality but number that is a species of quantity. Now this is
clearly false. For since division causes plurality and indivision
unity, we must judge of one and many according to the various
kinds of division. Now there is a kind of division which alto­
gether transcends the genus of quantity, and this is division
according to formal opposition which has nothing to do with
quantity. Hence the plurality resulting from such a division, and
the unity which excludes such a division, must needs be more
universal and comprehensive than the genus of quantity.
Again there is a division of quantity which does not transcend
the genus of quantity. Wherefore the plurality consequent to
this division and the unity which excludes it are in the genus
of quantity. This latter unity is an accidental addition to the
thing of which it is predicated, in that it measures it: otherwise
the number arising from this unity would not be an accident nor
the species of a genus. Whereas the unity that is convertible
with being adds nothing to being except the negation of division;
not that it signifies indivision only, but substance with indivi­
sion : for one is the same as individual being. In like manner the

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Philosophy of St. Thomas: Metaphysics
plurality that corresponds to this unity adds nothing to the
many things except distinction, which consists in each one not
being the other: and this they have not from anything added to
them but from their proper forms.
It is clear, then, that one which is convertible with being
posits being but adds nothing except the negation of division.
And the number corresponding to it adds this to the things
described as many, that each of them is one, and that each of
them is not the other, wherein is the essence of distinction.
Accordingly then, while one adds to being one negation inas­
much as a thing is undivided in itself; plurality adds two nega­
tions, inasmuch as a certain thing is undivided in itself, and
inasmuch as distinct from another; i.e. one of them is not the
other. (From On the Power of God, trans, by Laurence Chap­
eóte, O.P. Reprinted by permission of Tire Newman Press, Pub­
lishers.)
X. LOGICAL TRUTH AND ONTOLOGICAL TRUTH

(Summa theol. la, q. 16, a. 1 c)

Is truth in the intellect? Or is it in things? Aristotle’s view
was that it is primarily in the intellect. The Augustinian tra­
dition took more to the view of an objective or ontological
truth. In St. Thomas both positions are recognized. Truth,
he agrees with Aristotle, is primarily in the intellect, but
secondarily or derivatively it is also in things. Our excerpt,
from the Summa theologiae, shows how he goes about
reconciling the two points of view. (Collate with supra,
“The True,” p. 134).
As good names that towards which the appetite tends, so the
true names that towards which the intellect tends. Now there is
this difference between the appetite and the intellect, or any

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273
knowledge whatsoever, that knowledge is according as the thing
known is in the knower, while appetite is according as the desirer
tends towards the thing desired. Thus the term of the appetite,
namely good, is in the desirable thing, and the term of the intel­
lect, namely the true, is in the intellect itself.
Now as good exists in a thing so far as that thing is related
to the appetite—and hence the aspect of goodness passes on
from the desirable thing to the appetite, in so far as the appetite
is called good if its object is good; so, since the true is in the
intellect in so far as the intellect is conformed to the thing un­
derstood, the aspect of the true must needs pass from the intel­
lect to the thing understood, so that also the thing understood
is said to be true in so far as it has some relation to the intellect.
Now a thing understood may be in relation to an intellect
either essentially or accidentally. It is related essentially to an
intellect on which it depends as regards its being, but acciden­
tally to an intellect by which it is knowable; even as we may say
that a house is related essentially to the intellect of the archi­
tect, but accidentally to the intellect upon which it does not
depend. Now we do not judge of a thing by what is in it acci­
dentally, but by what is in it essentially. Hence, everything is
said to be true absolutely, in so far as it is related to the intellect
on which it depends; and thus it is that artificial things are said
to be true as being related to our intellect. For a house is said
to be true that fulfills the likeness of the form in the architect’s
mind; and words are said to be true so far as they are the signs
of truth in the intellect. In the same way, natural things are
said to be true in so far as they express the likeness of the species
that are in the divine mind. For a stone is called true which
possesses the nature proper to a stone, according to the precon­
ception in the divine intellect. Thus, then, truth resides pri­
marily in the intellect, and secondarily in things according as
they are related to the intellect as their source. (From Basic

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Writings of Saint Thomas Aquinas, edited by Anton C. Pegis.
Copyright Random House, Inc., 1945. Reprinted by permission
of Random House, Inc., Publishers.)
XI. WHETHER GOOD ADDS ANYTHING
TO BEING

(De Verit. q. 21, a.l)

The question which always seems uppermost in the mind
of St. Thomas when dealing with the transcendentals is
whether they add anything positive and real to being, or
differ from it only in concept. In the present selection the
question is treated with exceptional thoroughness. The
elucidations and resolutions set forth serve at the same time
to illuminate the general doctrine of transcendentals and
even, to some extent, the basic divisions of being—circum­
stances which lend the more interest to the piece. (Collate
with supra, “The Good,” p. 142).
Something can be added to something else in three ways:
1) It adds some reality which is outside the essence of the
thing to which it is said to be added. For instance, white adds
something to body, since the essence of whiteness is something
beyond that of body.
2) One thing is added to the other as limiting and determin­
ing it. Man, for instance, adds something to animal—not indeed
in such a way that there is in man some reality which is com­
pletely outside the essence of animal; otherwise it would be
necessary to say that it is not the whole of man which is animal
but only a part. Animal is limited by man because what is con­
tained in the notion of man determinately and actually, is only
implicitly and, as it were, potentially contained in the notion
of animal. It belongs to the notion of man that he have a ra-

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275
tional soul; to the notion of anima], that it have a soul, without
its being determined to rational or nonrational. And yet that
determination by reason of which man is said to add something
to animal is founded in reality.
3) Something is said to add to something else in concept only.
This occurs when something which is nothing in reality but
only in thought, belongs to the notion of one thing and not to
the notion of the other, whether that to which it is said to be
added is limited by it or not. Thus blind adds something to man,
namely blindness, which is not a being in nature but merely
a being in the thought of one who knows privations. By it man
is limited, for not every man is blind. But when we say “a blind
mole,” no limitation is placed by what is added.
It is not possible, however, for something to add anything
to being in general in the first way, though in that way there
can be an addition to some particular kind of being; for there
is no real being which is outside the essence of being in general,
though some reality may be outside the essence of this being.
But in the second way certain things are found to add to being,
since being is contracted by the ten categories, each of which
adds something to being—not, of course, an accident or differ­
ence which is outside the essence of being, but a definite man­
ner of being which is founded upon the very essence [Schmidt:
existence] of the thing. It is not in this way, however, that good
adds something to being, since good itself, like being, is divided
into the ten categories, as is made clear in the Ethics [I, 6, 1096 a
19-30].
Good must, accordingly, either add nothing to being or add
something merely in concept. For if it added something real,
being would have to be contracted by the character of good to
a special genus. But since being is what is first conceived by
the intellect, as Avicenna says [Metaph. I, 6, 72rb], every other
noun must either be a synonym of being or add something at

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least conceptually. The former cannot be said of good, since
it is not mere babble to call a being good. Thus good, by the
fact of its not limiting being, must add to it something merely
conceptual. . . . Accordingly, to being, the first conception of
the intellect, one adds what is merely conceptual—a negation;
for it means undivided being. As for true and good, which are
predicated positively, these too cannot add anything except a
relation which is merely conceptual. (From Truth, Vol. Ill,
Translated by Robert W. Schmidt, S.J., Copyright Henry Regnery Company, 1954. Reprinted by permission of Henry Regnery Company, Publishers.)

XII. CONCERNING BEING AND ESSENCE
St. Thomas was not the first to reduce being to essence
and existence, a reduction, as it were, to its ultimate com­
ponents. Several earlier commentators of Aristotle had
spoken in much the same terms, though their meaning
often left much to be desired. The fact of the matter is
that with St. Thomas the doctrine of essence and existence
finds a development it had not known before. His first fullscale presentation occurs in De Ente et Essentia, written at
the beginning of his teaching career. His intent in this
comparatively small work is far from simple. But, disregard­
ing the parts which are more properly expositions in logic,
we may say that the metaphysical content establishes a
hierarchical classification of beings on the basis of increasing
simplicity, going from material substances (composed of
matter and form) to spiritual substances (composed only of
essence and existence), and culminating in God (absolutely
simple, in whom essence is identical with existence). More­
over, despite certain peculiarities, mostly of style, which
betray the precocious author, De Ente et Essentia is already

Texts
completely representative of the teaching which
was to maintain on the subject throughout
(Collate with supra, chapter 7, “Essence and
p. 201).

277
St. Thomas
his career.
Existence/’

A. On the meaning of the words “being” and “essence”

(De Ente et Essentia, Introduction & chap. 1)
A small mistake in the beginning is a great one in the end,
according to the Philosopher in the first book of De Caelo et
Mundo [I, 5, 271 b 13]. Moreover, as Avicenna declares early
in his Metaphysics [I, 6, 72rb], what the intellect first conceives
is being and essence. Consequently, lest we fall into error
through ignorance of them, we ought to state, with a view to
disclosing the difficulty they involve: 1) what is meant by the
terms being and essence; 2) how they are found in diverse things;
and 3) how they are related to the intentions of logic, namely
genus, species, and difference. Moreover, we ought to acquire
knowledge of the simple from the composite, and arrive at what
is prior from what is posterior, so that beginning with easier
matters, we may advance more suitably in knowledge. For this
reason we ought to go from the meaning of being to the mean­
ing of essence.
It should be known, then, that being by itself [per se] is
spoken of in two ways, as the Philosopher says in the fifth book
of the Metaphysics [A, 7, 1017 a 22-35]. hi the first way it is
divided into the ten categories; in the second way it signifies
the truth of propositions. The difference between the two is that
in the second sense we can call everything being about which
we can form an affirmative proposition, even though it may posit
nothing in reality. Thus, we call even privations and negations
beings, for we say that affirmation is opposed to negation, and
that blindness is in the eye. But in the first sense, only that can

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Philosophy of St. Thomas: Metaphysics
be called being which posits something in reality. In this sense,
then, blindness and the like are not beings.
Accordingly, the term essence is not taken from being in the
second sense of the word. For, as is clear in the case of priva­
tions, in that sense we call some things beings which do not
have an essence. Essence is rather taken from being in the first
sense. That is the reason why the Commentator declares in the
same place [In V Metaph. 7, t. c. 14; 55v-aj6] that being in the
first sense of the word is that which signifies the essence of a
thing. And because, as we have said, being in this sense is di­
vided into the ten categories, essence must signify something
common to all natures through which different beings are placed
in different genera and species. For example, humanity is the
essence of man, and so with other things. Moreover, since that
by which a thing is constituted in its proper genus and species
is what is signified by the definition expressing what the thing
is, philosophers have taken to using the word quiddity for the
word essence. The Philosopher frequently calls this the what a
thing was to be [quod quid erat esse], in other words, that by
which a thing is a what.
B. Essence in composite substances

(De Ente et Essentia, chap. 2)

Form and matter are found in composite substances, for ex­
ample, soul and body in man. It cannot be said, however, that
either one of these alone is called the essence. That matter alone
is not the essence of a thing is evident, for through its essence a
thing is knowable and fixed in its species and genus. But matter
is not a principle of knowledge, nor does it determine anything
to a genus or species. Only that which is in act does this. Neither
can the form alone of a composite substance be called its es­
sence, although some would endeavor to assert it. For it is evi­

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279
dent from what has been said that essence is what the definition
of a thing signifies. Now, the definition of physical substances
includes not only form but also matter; otherwise there would be
no difference between physical and mathematical definitions.
Neither can it be said that the definition of a physical substance
includes matter as something added to its essence, or as a being
outside of its essence, because this manner of definition is more
proper to accidents, which do not have a perfect essence. That
is the reason why the definition of accidents must include their
subject, which is outside their genus. Evidently, then, essence
embraces both matter and form.
We cannot say, however, that essence signifies the relation
existing between matter and form, or something added to them.
This would of necessity be accidental or extraneous to the thing,
and it would not enable us to know the thing: none of which
characteristics fits essence. For, through form, which is the ac­
tuality of matter, matter is rendered being in act and a substance
[hoc aliquid]. What is added to it later, then, does not make
matter to be actual without qualification, but to be actually
such, as accidents likewise do. Whiteness, for instance, makes a
being actually white. Accordingly, when such a form is acquired,
we do not say something comes into being absolutely, but in a
certain respect [non simpliciter, sed secundum quid]. It remains,
then, that the word essence in composite substance signifies the
composite of matter and form.
C. Essence in separate substances

(De Ente et Essentia, chap. 4)
It remains for us to see in what way essence is in separated
substances, namely in the soul, in the intelligences, and in the
First Cause. Although everyone admits the simplicity of the
First Cause, some try to introduce the composition of matter

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Philosophy of St. Thomas: Metaphysics
and form in the intelligences and in souls. The originator of this
doctrine seems to have been Avicebron, the author of the Forts
Vitae. But it is not in accord with what philosophers generally
say, since they call these substances separated from matter, and
they prove that they are entirely immaterial.
The best demonstration of this is from their power of under­
standing. We see that forms are not actually intelligible unless
they are separated from matter and material conditions; nor are
they rendered actually intelligible except through the power of
an intelligent substance which receives them within itself and
actualizes them. Every intelligent substance, then, must be in
every way free from matter, neither having matter as part of
itself, nor being, like material forms, a form impressed on mat­
ter. Nor can it be asserted that not any matter whatsoever, but
only corporeal matter stands in the way of intelligibility. If cor­
poreal matter alone stood in the way of intelligibility, then
matter must impede intelligibility because of its corporeal form,
since matter is called corporeal only when it exists under a cor­
poreal form. But this is impossible, because a corporeal form
itself, like other forms, is actually intelligible when abstracted
from matter.
It follows that there is no composition of matter and form
in a soul or an intelligence, so that essence in these substances
would be like essence in corporeal substances. But there is in
them the composition of form and the act of existing [esse],
Tirus, in the commentary on the ninth proposition of the Liber
de Causis it is said that an intelligence is a being having form
and the act of existing; and form is understood here as the es­
sence itself or the simple nature.
It is easy to see how this is so. Whatever things are so related
to each other that one is the cause of the other’s existing, the
one which is the cause can exist without the other, but not con­
versely. Now, we find the relation of matter and form such that

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281
form makes matter exist. It is thus impossible that matter exist
without some form. On the other hand, it is not impossible that
some form exist without matter, for form as such does not de­
pend on matter. If we find some forms which can exist only in
matter, this happens to them because they are far removed from
the First Principle, which is primary and pure act. So, those
forms closest to the First Principle subsist in virtue of them­
selves without matter. For, as we have said, not every kind of
form requires matter, and the intelligences are forms of this
kind. It is not necessary, then, that the essences or quiddities
of these substances be other than form itself.

Although substances of this kind are forms only, and without
matter, they are not in every way simple, so as to be pure act.
They do have an admixture of potency, which is evident from
the following consideration. Whatever does not belong to the
notion of essence or quiddity comes from without and enters
into composition with the essence, for no essence is intelligible
without its essential parts. Now, every essence or quiddity can
be understood without anything being known of its existence.
I can know what a man or a phoenix is and still be ignorant
whether it exists in reality. From this it is clear that the act of
existing is other than essence or quiddity, unless perhaps there
be a being whose quiddity is its very act of existing [esse]. And
there can be only one such being, the First Being. For nothing
can be multiplied except: 1) through the addition of some dif­
ference, as the generic nature is multiplied into species; or 2) by
the form being received in different parts of matter, as the
specific nature is multiplied in different individuals; or 3) by
one thing being separate and another thing being received in
something—for instance, if there were a separated heat, by
reason of its very separation it would be different from heat
which is not separated. But, should there exist some being which

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is simply the act of existing, so that the act of existing be itself
subsistent, a difference cannot be added to this act of existing,
because then it would not be purely and simply the act of exist­
ing, but the act of existing plus a certain form. Much less can
matter be added to it, because then it would not be a subsistent,
but a material, act of existing. So we conclude that there can
only be one such being which is its very act of existing. With
this exception, in every other thing its act of existing is other
than its quiddity, nature, or form. In the pure intelligences,
therefore, the act of existing must be in addition to their form,
and for this reason it has been said that an intelligence is form
and the act of existing.
Now, whatever belongs to a being is either caused by the
principles of its nature, as the capability of laughter in man,
or it comes to it from some extrinsic principle, as light in the
air from the sun’s influence. But it is impossible that the act of
existing be caused by a thing’s form or its quiddity (I say caused
as by an efficient cause); for then something would be the cause
of itself and would bring itself into existence—which is impos­
sible. Everything, then, which is such that its act of existing is
other than its nature must needs have its act of existing from
something else. And since every being which exists through an­
other is reduced, as to its first cause, to one existing in virtue
of itself, there must be some being which is the cause of the
existing of all things because it itself is the act of existing alone.
If that were not so, we would proceed to infinity among causes,
since, as we have said, every being which is not the act of exist­
ing alone has a cause of its existence. Clearly, then, an intelli­
gence is form and act of existing, and it has its act of existing
from the First Being, which is simply act of existing. This is
the First Cause, God.
Now, every being receiving something from another is poten­
tial with respect to what it receives, and what is received in it is

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283
its act. The quiddity itself, then, or the form which is the in­
telligence must be potential with respect to the existence which
it receives from God, and that existence [esse] is received as an
act. Potency and act are thus found in the intelligences, but
not form and matter, except in an equivocal sense. So, too, as
the Commentator says in his exposition of the third book of
De Anima [III, 2, t. c. 14, fol. róSvbq], to suffer, to receive, to
be a subject of, and all characteristics of this sort which appear
to belong to things by reason of matter, belong equivocally to
intellectual and corporeal substances.
Furthermore, since the quiddity of an intelligence is, as we
have said, the intelligence itself, its quiddity or essence is that
which is, and the act of existing it receives from God is that
whereby it is or subsists in the world of things. For this reason
it is said by some that a substance of this kind is composed of
“that by which it is” [quo est] and “that which it is” [quod est];
or, as Boethius says [De Hebd. PL 64, 1311C], of “that which is”
[quod est] and its “act of existing” [esse]. Since, then, both
potency and act are in the intelligences, finding multitude
among them will not be difficult, whereas it would be impos­
sible if there were no potency in them. Thus, the Commentator
declares in his exposition of the third book of De Anima [III,
1, t. c. 5, fol. i66rai6] that, if we did not know the nature of
the possible intellect, we could not find multitude among sep­
arated substances.
Accordingly, these substances are distinct from one another
by reason of their degree of potency and act. A superior intel­
ligence, closer to the First Being, has more act and less potency,
and so with the others. This gradation terminates in the human
soul, which holds the lowest place among intellectual substances.
As the Commentator states in his exposition of the third book of
De Anima [ibid. fol. i6ovb43], the possible intellect of the hu­
man soul bears the same relation to intelligible forms as prime

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matter, holding the lowest position in sensible existence, bears
to sensible forms. That is why the Philosopher compares it to
a blank tablet on which nothing is written [De Anima, III, 4,
430 a i]. Having more potency than the other intellectual sub­
stances, the human soul is so close to matter that a material
thing is taken to share in its own act of existing, so that from
soul and body there results in the one composite one act of
existing, although in so far as it is the soul’s act of existing it
is not dependent on the body. After that form which is the soul,
other forms are found, having still more potency and still closer
to matter, to such a point that they do not exist without matter.
Among these forms, too, we find an order and hierarchy, until
we reach the primary forms of the elements, which are closest
to matter. Being so close to matter, they operate only according
to the exigencies of active and passive qualities and other dis­
positions which prepare matter to receive form.

D. Conclusion: Three ways essence is found
in substances
(De Ente et Essentia, chap. 5)

It is evident from the foregoing how essence is found in dif­
ferent beings. Indeed, we find in substances a threefold manner
of having essence.
1) First, there is a being, God, whose essence is His very act
of existing. That explains why we find some philosophers as­
serting that God does not have a quiddity or essence, because
His essence is not other than His act of existing. From this it
follows that He is not in a genus, for the quiddity of anything
in a genus must be other than its act of existing, since the dif­
ferent beings within a genus or species have the same generic
or specific quiddity or nature, whereas their act of existing is
different.

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285
If we say, moreover, that God is purely and simply the act
of existing, we need not fall into the mistake of those who assert
that God is that universal existence whereby each thing for­
mally exists. The act of existing which is God is such that no
addition can be made to it. Consequently, in virtue of its very
purity it is an act of existing distinct from every other, even as
a separated color, if there were one, would by its very separation
be distinct from a color that is not separated. That is why, in
the commentary on the ninth proposition of the Liber de Causis,
it is said that the First Cause, being purely and simply the act
of existing, is individualized by its unalloyed perfection. But
just as existing-in-general [esse commune] does not include in
its notion any addition, so neither does it imply any exclusion
of addition; otherwise, nothing could be understood to exist in
which something would be added over and above the act of
existing.
Similarly, although God is simply the act of existing, it is
not necessary that He lack the other perfections or excellences.
On the contrary, He possesses all perfections of all genera of
beings; so He is said to be unqualifiedly perfect, as the Philoso­
pher and the Commentator assert in the fifth book of the
Metaphysics [A, 16, 1021 b 30; In V Metaph. 16, t. c. 21, fol.
62310-13]. But He possesses these perfections in a more excel­
lent way than other things, for in Him they are one, while in
other things they are diversified. So, too, if someone through
one quality could perform the operations of all the qualities,
he would in that one quality possess all the qualities. In the
same way, God possesses all perfections in His very act of
existing.
2) In a second way, we find essence in created intellectual
substances. Their act of existing is other than their essence,
although their essence is immaterial. Thus, their act of existing
is not a separated, but a received one; and it is therefore lim-

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Philosophy of St. Thomas: Metaphysics
ited and restricted to the capacity of the receiving nature. Their
nature or quiddity, however, is separated and unreceived in any
matter. Thus the Liber de Causis states that the intelligences
are unlimited from below and limited from above. They are
limited as to their act of existing which they receive from above,
but they are unlimited from below because their forms are not
limited to the capacity of some matter receiving them.
Consequently, in these substances, as we have said, we do
not find many individuals in one species, except in the case of
the human soul because of the body to which it is united. Al­
though the soul’s individuation depends on the body for the
occasion of its beginning, since the soul comes into possession
of its individuated act of existing only in the body of which it
is the act, it is not necessary that the individuation come to an
end when the body is removed. Since its act of existing is in­
dependent, once it has acquired an individuated act of existing
from its being made the form of this particular body, that act
of existing always remains individuated. Hence, Avicenna states
[De Anima, V, 3, fol. 24rb] that the individuation and multi­
plication of souls depend on the body in the beginning but not
in the end.
What is more, because the quiddity in these substances is not
identical with their act of existing, they are able to be placed
in a category. So, we find in them genus, species, and difference,
although their proper differences are hidden from us. But even
in the case of sensible things the essential differences themselves
are unknown to us; hence we have to signify them by the ac­
cidental differences which arise from the essential ones, as we
designate a cause by its effect. Biped, for example, is given as
the difference of man. With regard to immaterial substances, we
do not know their proper accidents; hence we cannot designate
their differences either in themselves or through their accidental
differences.

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Texts

3) We find essence in a third way in substances composed
of matter and form. Their act of existing is received and lim­
ited because they have it from another; also, their nature or
quiddity is received in designated matter. Thus they are limited
both from above and from below. Moreover, because of the di­
vision of designated matter, the multiplication of individuals
in one species is possible in such substances. . . . (From On
Being and Essence, trans, by Armand A. Maurer, C. S. B. Copy­
right The Pontifical Institute of Mediaeval Studies, Publishers,
1949. Reprinted by permission of the Publishers.)
XIII. THAT IN GOD ESSENCE AND
EXISTENCE ARE THE SAME

(Summa Contra Gentiles, I, 22)

Whereas in creatures essence and existence are really
distinct, in God they are really one, identical. Indeed, the
identity of God’s essence with His existence is not only the
hallowed expression of God’s nature; it is also the ultimate
solution to the problem of being. In the text we have chosen,
St. Thomas develops his thought on this point more thor­
oughly than in the corresponding article of the Summa
theologiae (la, q.3, a.4). In a preceding chapter (I, 18) he
had declared that in God there is no composition whatever;
and, more immediately (I, 21), that He is His very essence.
Then follows the chapter which constitutes our present
reading. (Collate with supra, chapter 7, “Essence and Exist­
ence,” p. 201).
From what has been proved above, we can further prove that
in God essence or quiddity is not something other than His being
[esse: existence].

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Philosophy of St. Thomas: Metaphysics
i) For it was shown above (ch. 13) that there is some being
that must be through itself, and this is God. If, then, this being
that must be belongs to an essence that is not that which it is,
either it is incompatible with that essence or repugnant to it,
as to exist through itself is repugnant to the quiddity of white­
ness; or it is compatible with it or appropriate to it, as to be in
another is to whiteness. If the first alternative be the case, the
being that is through itself necessary will not befit that quiddity,
just as it does not befit whiteness to exist through itself. If the
second alternative be the case, either such being must depend
on the essence, or both must depend on another cause, or the
essence must depend on the being [esse]. Tire first two positions
are contrary to the nature of that which is through itself a neces­
sary being; for if it depends on another, it is no longer a neces­
sary being. From the third position it follows that that quiddity
is added accidentally to the thing that is through itself a neces­
sary being; for what follows upon a thing’s being is accidental
to it and hence not its quiddity. God, therefore, does not have
an essence that is not His being [esse].
But against this conclusion it can be objected that that being
does not absolutely depend on that essence, so as not to be
unless the essence existed; it depends, rather, on the essence as
regards the union by which it is joined to it. Thus, that being
is through itself necessary, but its union with the essence is not.
However, this reply does not escape the aforementioned dif­
ficulties. For, if that being can be understood without that
essence, it will follow that the essence is related to that being
in an accidental way. But that being is that which is through
itself a necessary being. Therefore, that essence is related in an
accidental way to that which is through itself a necessary being.
It is, therefore, not its essence. But that which is through itself
a necessary being is God. That essence, then, is not the essence
of God, but some essence below God. On the other hand, if

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28g
that being cannot be understood without that essence, it de­
pends absolutely on that on which its union to that essence
depends. We then reach the same impasse as before.
2) Another argument. Each thing is through its own being.
Hence, that which is not its own being is not through itself a
necessary being. But God is through Himself a necessary being.
He is, therefore, His own being.
3) Again, if God’s being is not His essence, and cannot be
part of that essence, since, as we have shown, the divine essence
is simple [ch. 18], such a being must be something outside the
divine essence. But whatever belongs to a thing and is yet not
of its essence belongs to it through some cause; for, if things
that are not through themselves one are joined, they must be
joined through some cause. Being, therefore, belongs to that
quiddity through some cause. This is either through something
that is part of the essence of that thing, or the essence itself, or
through something else. If we adopt the first alternative, and it
is a fact that the essence is through that being, it follows that
something is the cause of its own being. This is impossible, be­
cause, in their notions, the existence of the cause is prior to
that of the effect. If then, something were its own cause of being,
it would be understood to be before it had being—which is im­
possible, unless we understand that something is the cause of its
own being in an accidental order, which is being in an accidental
way. This is not impossible. It is possible that there be an acci­
dental being that is caused by the principles of its subject before
the substantial being of its subject is understood as given. Here,
however, we are speaking of substantial being, not accidental
being. On the other hand, if the being belongs to the essence
through some other cause, then this follows: given that what
acquires its being from another cause is something caused, and
is not the first cause, whereas God, as was demonstrated above
[ch. 13], is the first cause and has no cause, the quiddity that

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Philosophy of St. Thomas: Metaphysics
acquires its being from another is not the quiddity of God.
God’s being must, therefore, be His quiddity.
4) Being [esse], furthermore, is the name of an act, for a
thing is not said to be because it is in potency but because it
is in act. Everything, however, that has an act diverse from it
is related to that act as potency to act; for potency and act are
said relatively to one another. If, then, the divine essence is
something other than its being, the essence and the being are
thereby related as potency and act. But we have shown that in
God there is no potency, but that He is pure act [ch. 16]. God’s
essence, therefore, is not something other than His being.
5) Moreover, if something can exist only when several ele­
ments come together, it is composite. But no thing in which
the essence is other than the being can exist unless several
elements come together, namely the essence and the being.
Hence, every thing in which the essence is other than the being
is composite. But, as we have shown, God is not composite
[ch. 18]. Therefore, God’s being is His essence.
6) Every thing, furthermore, exists because it has being. A
thing whose essence is not its being, consequently, is not through
its essence but by participation in something, namely being
itself. But that which is through participation in something
cannot be the first being, because prior to it is the being in which
it participates in order to be. But God is the first being, with
nothing prior to Him. His essence is, therefore, His being.
7) This sublime truth Moses was taught by God. When
Moses asked the Lord: “If the children of Israel say to me:
what is His name? What shall I say to them?” The Lord re­
plied: “I AM WHO AM . . . Thou shalt say to the children
of Israel: HE WHO IS hath sent me to you” (Exod. 3:13, 14).
By this the Lord showed that His own proper name is HE
WHO IS. Now, names have been devised to signify the na­
tures or essences of things. It remains, then, that the divine
being is God’s essence or nature.

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291
8) Catholic teachers have likewise professed this truth. For
Hilary writes in his book De Trinitate [VII, n; PL. 10, 208B]:
“Being is not an accident in God but subsisting truth, the abid­
ing cause and the natural property of His nature.” Boethius
also says in his own work De Trinitate [II; PL. 64, 1250B] : “The
divine substance is being itself, and from it comes being.” (From
On the Truth of the Catholic Faith, by Anton Pegis. Copyright
1955 by Doubleday & Company, Inc. Reprinted by permission
of the Publisher.)
XIV. IS IT NECESSARY THAT EVERY BEING
BE CREATED BY GOD?

(Summa theol. la, q.44, a.i)

This article begins the treatise on creation in the Summa
theologiae. It is also an article in which, we might add, the
metaphysical structure of being, or being in its concrete
reality, is traced down to its ultimate feature. Arguing, by
causality, from the fact of contingent being, St. Thomas
had earlier made good the existence of a first being, identi­
cal, as we have seen, with its essence. It is similarly by
causality that the present article argues the creation of all
other beings. As in the Fourth Way, and in the capital
demonstration of identity of essence and existence in God,
so in the present instance St. Thomas, it is noteworthy,
bases the argument on the relation of participated being to
nonparticipated, or per se being. Without a doubt, then, it
is within the framework of participation that the meta­
physical cast of being acquires its most complete, indeed
its final delineation. (Collate with supra, “The First Cause,”
p. 229).
Objection 1. It would seem that it is not necessary that every
being be created by God. For there is nothing to prevent a thing

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Philosophy of St. Thomas: Metaphysics
from being without that which does not belong to its essence,
as a man can be found without whiteness. But the relation
of the thing caused to its cause does not appear to be essential
to beings, for some beings can be understood without it. There­
fore they can exist without it; and hence it is possible that some
beings should not be created by God.
Obj. 2. Further, a thing requires an efficient cause in order
to exist. Therefore whatever cannot not-be does not require an
efficient cause. But no necessary thing can not-be, because what­
ever necessarily exists cannot not-be. Therefore as there are many
necessary things in existence, it appears that not all beings are
from God.
Obj. 3. Further, among whatever things there is a cause, there
can be demonstration by that cause. But in mathematics dem­
onstration is not made by the efficient cause, as appears from
the Philosopher [Metaph. B, 2, 996 a 29]. Therefore not all
beings are from God as from their efficient cause.
On the contrary, It is said [Rom. xi. 36]: Of Him, and by
Him, and in Him are all things.
I answer that, It must be said that everything that in any way
is, is from God. For whatever is found in anything by participa­
tion must be caused in it by that to which it belongs essentially,
as iron becomes heated by fire. Now it has been shown above,
when treating of the divine simplicity, that God is self-subsist­
ing being itself [q. 3, a. 4], and also that subsisting being can
be only one [q. 7, a. 1, ad 3; a. 2]; just as, if whiteness were
self-subsisting, it would be one, since whiteness is multiplied
by its recipients. Therefore all beings other than God are not
their own being, but are beings by participation. Therefore, it
must be that all things which are diversified by the diverse par­
ticipation of being, so as to be more or less perfect, are caused by
one First Being, who possesses being most perfectly.
Hence Plato said that unity must come before multitude [cf.

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293
St. Augustine, De Civit. Dei, VIII, 4]; and Aristotle said that
whatever is greatest in being and greatest in truth is the cause
of every being and of every truth, just as whatever is the great­
est in heat is the cause of all heat [Metaph. a, 1, 993 b 25].
Reply Obj. 1. Though relation to its cause is not part of the
definition of a thing caused, still it follows as a result of what
belongs to its nature. For, from the fact that a thing is being
by participation, it follows that it is caused. Hence such a being
cannot be without being caused, just as man cannot be without
having the faculty of laughing. But, since to be caused does not
enter into the nature of being taken absolutely, that is why there
exists a being that is uncaused.
Reply Obj. 2. This objection has led some to say that what is
necessary has no cause [cf. Phys. VIII, 1, 252 a 35]. But this is
manifestly false in demonstrative sciences, where necessary prin­
ciples are the causes of necessary conclusions. And therefore
Aristotle says that there are some necessary things which have
a cause of their necessity [Metaph. A, 5, 1015 b 9]. But the
reason why an efficient cause is required is not merely because
the effect can not-be, but because the effect would not be if the
cause were not. For this conditional proposition is true, whether
the antecedent and consequent be possible or impossible.
Reply Obj. 3. Although they are not abstract in reality, mathematicals are considered in abstraction by the reason. Now, it
belongs to a thing to have an efficient cause according as it has
being. And so, although mathematicals do have an efficient
cause, it is not according to their relation to their efficient cause
that they fall under the consideration of the mathematician.
Therefore there is no demonstration by means of an efficient
cause in mathematics. (From Basic Writings of Saint Thomas
Aquinas, edited by Anton C. Pegis. Copyright Random House,
Inc., 1945. Reprinted by permission of Random House, Inc.,
Publishers.)

Glossary of Technical Terms

A

ABSTRACTION.—In general, the act whereby the intellect
segregates an aspect of a thing (from other aspects).
1. Basically, abstraction is the act whereby the intellect
educes the intelligible from the material conditions under
which it is given to the senses.
2. In total abstraction the intellect draws the universal (or
logical whole) from the individuals comprising its inferiors;
the concept thus obtained is that of a genus or species (ani­
mal, man). —In formal abstraction one of the formal aspects
of a thing is marked out; e.g. in mathematics, the quantita­
tive aspect of bodies.
3. Degrees of abstraction. Tire three principal levels of
intelligibility (physical, mathematical, metaphysical) which
the human intellect can consider in its object by progressive
relinquishment of the conditions of matter.
ACCIDENT.—1. Metaphysics: predicamental accident. That
to which it pertains to exist in another as in a subject of
inherence; e.g. color, magnitude. Opposed to substance. The

2g6
Glossary of Technical Terms
nine accidents, with substance, constitute the categories or
predicaments.
2. Logic: predicable accident. That which is said of a sub­
ject by way of quality and as not necessary; e.g. the quality
“learned” said of a man.
3. Accidental being [ens per accidens]. Being which does
not have proper (or essential) causality; e.g. that this man is
learned is accidental to him. Opposed to being which exists
essentially [ens per se],
ACT.—That which is complete or perfect in its order, as against
what is only in potency.
1. Entitative act (first act). The act through which a being
is simply and formally what it is.
2. Operative act (second act). Designates the activity or
operation of a being, which presupposes that it be in first act.
3. Pure act. Act which excludes all potentiality, namely
God.
ACTION [actio, actus]. —1. Designates the fact of activity in
a subject, its operation. One of the nine predicamental acci­
dents. Opposed to passion.
2. Transitive action. Action which terminates outside the
subject and perfects or modifies not the subject primarily, but
another; e.g. cutting, burning.
3. Immanent action. Action, which terminates in its sub­
ject and perfects the subject itself; e.g. thinking, willing.
AGENT.—The subject, whether person or thing, which exer­
cises an activity.
“AGIBILE” [the “do-able”]. —That which pertains to the
realm of immanent action, or of morality; more precisely
that which can be the object of a “human act” as such.
Opposed to factibile [the make-able], which designates the
object of material production.
ALTERATION.—In Aristotelian physics, a qualitative change;

Glossary of Technical Terms
297
e.g. variation of temperature. Alteration is one of the three
species of accidental motion distinguished by Aristotle.
ANALOGOUS.—Property of a concept or term which refers to
its inferiors, or the things it embraces, with a meaning in each
case partly the same and partly different. Opposed to uni­
vocal and equivocal. Principal division:
1. Analogy of attribution. Analogy of a term which applies
to several things in view of their relation to one other thing
(the primary analogate); e.g. “healthy,” which applies to med­
icine, complexion, diet, etc. because of the relation that exists
between these things and an animal, which alone is healthy
in the formal sense.
2. Analogy of proportionality. Analogy of a concept or term
which applies to several things by reason of an intrinsic simi­
larity, specifically a similarity of relations; e.g. vision, ocular
or intellectual.
ANTECEDENT.—The premises of a syllogism taken together
in reference to the conclusion, or consequent.
APPETITE.—1. In a very general sense, the inclination or
tendency which follows on the nature of a being.
2. Natural appetite (or innate). The purely passive dispo­
sition of a being toward its end as determined by its natural
form; e.g. in ancient physics, the downward tendency of a
stone. Noncognitive beings have only natural appetite. In
cognitive beings it designates the radical disposition of a
faculty to its end; e.g. of the intellect to truth, of the will to
good.
3. Animal appetite (or elicited). In cognitive beings, the
faculty or actual inclination which follows on the apprehen­
sion of a form: sensitive appetite, if the form or knowledge in
question is of the sensible order; intellectual appetite, or will,
when the presupposed knowledge is of the rational order.
APPREHENSION.—Act by which the intellect simply grasps

298
Glossary of Technical Terms
an object, neither affirming nor denying anything of it. Sim­
ple apprehension is the first of the three operations of the
human intellect.
ARGUMENTATION.—Verbal expression of an act of reason­
ing, third operation of the intellect.
ART.—i. Objectively or physically, designates the extrinsic
principle, rational in character, of an operational process; e.g.
the art of building as compared with the act of building. Op­
posed to nature, an immanent or intrinsic principle of activ­
ity. Art constitutes the domain of the fashioned and fabri­
cated, in contrast to the natural, the work of nature.
2. Considered in reference to the subject, art is a habitus
(first species of quality), a stable disposition perfecting the
subject relative to a given activity. In this respect it is one of
the five intellectual virtues, that which directs the activity of
production.
“ASEITY.”—Property of being which consists in self-existence,
or self-subsistence. Taken strictly, “aseity” belongs only to
God and is his most fundamental attribute.
ATOM.—Ultimate, indivisible physical element. In Aristotelian
philosophy atoms are, however, subject to generation and
corruption, and on this score are composed of prime matter
and substantial form.
ATTRIBUTE.—i. Logic. Term of a proposition telling what is
affirmed or denied of a subject. Synonym: predicate.
2. Metaphysics. The attributes of God, the different aspects
of his nature.
ATTRIBUTION.—i. Act of referring the predicate to the sub­
ject. Synonym: predication. In Scholastic Latin this act is also
designated by the verb “to say” (dicere). There are various
modes of attribution—essential (per se), accidental (per acci­
dens), etc.
2. One of the forms of analogy, that of attribution.

Glossary of Technical Terms
299
AUGMENTATION. —A quantitative change. Augmentation
(or diminution: decrementum) is one of the species of physi­
cal change distinguished by Aristotle. Refers only to living
things.
AXIOM.—A self-evident proposition governing a series of dem­
onstrations. Equivalent expressions: first principles, dignitates,
maximae propositiones, propositions “known in themselves”
(per se notae).

B
BEATITUDE.—1. Objectively, state of perfection of a rational
being that has attained its ultimate perfection.
2. Subjectively, the joy from conscious possession of the
supreme good.
BEING [ens, esse].—1. Expresses relation of essence to the act
of being, i.e. to existence.
2. Real being (actual or possible): what exists or can exist;
the being, considered as being, which is the formal object of
metaphysics.
3. Being of reason, or logical [ens rationis]: that which can
only exist in the intellect conceiving it.
“Being” is an analogical term, admitting of various accepta­
tions and divisions.
C
CATEGOREMATIC.—Property of terms which signify in
themselves; e.g. the term “man.” Opposed to syncategorematic terms, such as prepositions, which do not properly
signify except in conjunction with another; e.g. “they went to
Rome.”
CATEGORICAL.—1. Categorical proposition. One in which
there is simple or unqualified attribution of a predicate to a
subject; e.g. “Peter is a man.”

joo
Glossary of Technical Terms
2. Categorical syllogism. Common form of the syllogism,
in which only categorical propositions occur.
CATEGORIES (usually designated by the synonymous Latin
derivative, predicaments). —The supreme genera of being,
namely substance and the nine accidents: quantity, quality,
relation, action, passion, place, time, situation, possession.
CAUSALITY.—Properly, signifies the act itself of causing, i.e.
of actually producing something. There are as many types of
causality as there are types of causes.
CAUSE.—i. In the real order. That on which a thing depends
for its being or its becoming. The cause must be prior to the
effect, and really distinct from it, and the dependence of
the effect must be positive or real.
2. In the order of explanation. Cause is that which explains
or gives the reason of a thing. On this account science is said
to be: knowledge through causes.
3. Fourfold division (the basic types). Material cause: that
from which a thing is made and which remains in it. Formal
cause: that which determines a thing to a certain mode of
being. Efficient cause: that from which comes the first begin­
ning of change or of rest. Final cause: that for the sake of
which something is made or done.
4. Principal cause. That which produces its effect by its
own power or efficacy. Opposed to instrumental cause, which
acts only under motion from another.
CHANCE, [automaton, casus, fortuna].—1. In general, desig­
nates an accidental cause bearing on things which happen
rarely and are not intended by the agent, but could have been
sought as an end.
2. Chance, when it touches on tire activity of man, is called
fortune.
CHANGE [mutatio, motus],—1. In general, any transformation
or modification of a being of nature.

Glossary of Technical Terms
301
2. Substantial change (generation-corruption). Change
which terminates in a new substance.
3. Accidental change. Modification occurring in one and
the same substance. If the change falls under motion in the
strict sense, it is one of three: alteration, change of quality;
augmentation-diminution, change of quantity; local motion,
change of place.
COGITATIVE SENSE.—1. One of the four internal senses,
namely that through which the object perceived by the com­
mon sense is recognized as beneficial or harmful to the sub­
ject.
2. Corresponding to the cogitative, which is proper to man,
is the estimative sense in animals; e.g., it is in virtue of an in­
stinctive appraisal by this faculty that the sheep flees the wolf.
COMMON SENSE [sensus communis].—One of the internal
senses whose proper function is to perceive the activities of
the several external senses and to compare and discriminate
their presentations.
COMPREHENSION.—1. Logic. Sum of the notes comprising
a concept and distinguishing it from other concepts; e.g. the
comprehension of “man” includes the notes of substantiality,
life, animality, rationality. Opposed to extension.
2. Psychology. Act whereby the intellect grasps an object
all-inclusively.
CONCEPT.—That which represents a thing to the intellect.
Subjectively, what the intellect produces through its imma­
nent activity and in which it contemplates its object. Cor­
responding terms: “mental word,” “expressed species.”
CONCEPTION.—Tire act of forming a concept. Synonym:
the act of expression [dicere). The dicere is really distinct
from the act of grasping the object (the intelligere).
CONCUPISCIBLE APPETITE.—One of the two faculties of
the sensory appetite whose object is the good simply or easily

^02
Glossary of Technical Terms
attained, or the evil in like manner avoided. Distinguished
from irascible appetite, which bears on the difficult good or
evil, i.e. difficult of attainment or avoidance.
CONSEQUENCE.—Logical connection of propositions in de­
monstrative reasoning. The consequent designates the propo­
sition derived from the premises, called the antecedent.
CONTINGENT.—That which can not-be, or which does not
have in itself the sufficient reason of its existence. Opposed to
necessary, that which cannot not-be, or which cannot be other
than it is. All created beings are contingent.
CONTINUUM.—i. That which is composed of homogeneous
parts whose terms (limits) merge into one. Distinguished
from contiguous, which implies that the parts touch but their
limits remain distinct from each other.
2. Continuous quantity. That species of quantity which
results from continuous parts.
CONTRADICTORY.—i. Property of concepts which so ex­
clude each other as to admit of no middle ground between
them; e.g. white and not-white.
2. Contradictory propositions. Those of which one affirms
absolutely what the other denies. Such propositions differ
both in quantity and quality; e.g. “every man is just” and
“some man is not just.”
Contradiction constitutes the extreme mode of opposition.
The principle of noncontradiction is the supreme law of
thought.
CONTRARY.—i. Property of concepts which do not abso­
lutely exclude each other from the same subject, but admit of
a common genus; e.g. white and black (of the same genus:
color).
2. Contrary propositions. Those which are opposed in qual­
ity only; e.g. “every man is just” and “no man is just.”

Glossary of Technical Terms
303
CONVERSION.—Logic. Operation which interchanges the
subject and predicate of a proposition without destroying the
truth of the proposition; e.g. “no man is an angel” to “no
angel is a man.”
COPULA.—The verb “to be” as signifying the relation of sub­
ject and predicate in a proposition; e.g. “Peter is a man.”
CORRUPTION.—Change by which a substance is destroyed.
The correlative of generation, change which terminates in a
new substance. Every corruption necessarily involves a genera­
tion.

D
DEFINITION.—Complex term which makes explicit the na­
ture of a thing or the meaning of a concept. In the active
sense: the operation which results in the above.
DEMONSTRATION.—In strict Aristotelian logic, demonstra­
tion is a course of reasoning or a syllogism which begins with
premises that are true and leads to a conclusion that is certain,
or scientific (in the Aristotelian sense).
DIFFERENCE.—1. In general, that by which a thing is distin­
guished from another.
2. Specific difference. That which determines a genus to a
species distinct from other species of the same genus; e.g. the
difference “rational” determines the genus “animal” to the
species “man.”
DILEMMA.—Argument in which the antecedent states a dis­
junction from either member of which the same conclusion
will follow.
DISCRETE (QUANTITY).—One of the two species of quan­
tity, namely that which results from homogeneous parts which
are actually distinct (numerical quantity). Opposed to con­
tinuous (or concrete) quantity.

304
Glossary of Technical Terms
DISPOSITION.—Precise sense: state of being which, together
with habitus, constitutes the first species of quality but is less
stable than habitus.
DISTINCTION.—1. Difference by which two objects of
thought are distinguished or separated from each other.
2. Real distinction. That which is actually in the thing
itself; e.g. between substance and its accidents.
3. Distinction of reason (logical). That which is only in the
mind conceiving it, but may be founded in reality (rationis
ratiocinatae), e.g. distinction between genus and species; or
not founded (rationis ratiocinantis), e.g. two words designat­
ing the same thing.
DIVISION.—Complex term (or the operation) which distrib­
utes a whole (thing or name) into its parts.

E
ELECTION.—Designates the act by which the intellect, in the
course of the deliberate human act, chooses one of the means
presented to it.
ELEMENT.—1. Ultimate part of a complex whole.
2. Cosmology. First intrinsic component of a being of na­
ture, not divisible into specifically distinct parts. Ancient
cosmology acknowledged four elements: water, air, earth, fire.
END.—1. That for the sake of which something is made or
done. The end has the nature of cause, and stands at the
beginning of every causative process.
2. Divisions:
a) End as realized (in executions'), and as object of desire
(in intentione).
b) End to which a work or thing is appointed by its very
nature (finis operis), and end which the agent pursues
(finis operantis).

Glossary of Technical Terms
305
c) End or good desired (finis cujus gratin'), and for whom
this same good is desired (finis cui).
ENUNCIATION.—1. Mental or verbal expression correspond­
ing to the second operation of the mind.
2. Simple enunciation. Simple attribution of a predicate to
a subject.
3. Compound enunciation. Simple enunciations joined, as
the case may be, by the particles “if” (hypothetical), “or”
(disjunctive), “and” (conjunctive).
ENTELECHY [entelekeid].—Form or act considered as prin­
ciple of being (entitative act).
EQUALITY.—Relation of two identical quantities. Equality
is the mode of unity pertaining to the predicament of quan­
tity.
EQUIVOCAL.—Property of a term applied to various objects
according to meanings that differ absolutely in each case; ex.
“dog,” the animal and the constellation. Opposed to univocal
and analogous.
ESSENCE—That by which a thing is such and such and, in
consequence, differentiated from other things. (Or: that by
which a thing is what it is, as opposed to that by which it is.)
Essence enters into real composition with existence to consti­
tute a limited or contingent being. Corresponds to “second
substance,” which designates the intelligible content of sub­
stance.
ESTIMATIVE SENSE.—See Cogitative Sense.
EXEMPLAR.—Model according to which a thing is made.
The exemplary cause can be considered as an extrinsic formal
cause.
EXISTENCE [esse, existentia].—Ultimate act of a being which
causes it to be in reality.
EXTENSION.—Totality of subjects to which a concept ap­
plies. Opposed to comprehension.

jo6

Glossary of Technical Terms

F
FALSE.—Opposed to true. See Truth.
FIGURE.—i. Logic. Arrangement of the syllogism resulting
from the position of the middle term in the premises. There
are four figures of the syllogism.
2. Metaphysics. Qualitative mode which terminates quan­
tity. Comprises, with “form,” the fourth species of quality.
FORM.—In general, determinative principle of a being.
1. Physics. One of the three principles of physical being
(the two others: matter and privation).
a) Substantial form: that which, by determining prime
matter, constitutes a given nature.
b) Accidental form: determination supervening upon a
being already constituted as to its essence.
2. Metaphysics. By extension, any determination of being,
even a determination not received in matter; e.g. angels,
known as pure or separate forms.
3. Metaphysics. “Form,” together with “figure,” comprises
the fourth species of quality.
4. Logic. Form of reasoning (in syllogism): disposition of
premises considered independently of their intrinsic validity.
FORMAL.—1. That which stems from or relates to form. The
formal aspect always corresponds to what is determinate or
actual in a thing or a conception.
2. Formal object. Precise and determinate aspect attained
by a power or habitus. Opposed to material object.
FORTUNE.—See Chance.
FREE WILL [St. Thomas: liberum arbitrium, lit. “free judg­
ment”].—1. Basically, free will designates the power of will
whereby, in association with the intellect, it can choose one
thing rather than another.

Glossary of Technical Terms
307
2. Derivatively, the term “free will” can also be understood
of the act of the will, i.e. its act of choice or election. This
act, though in the will, always presupposes a judgment of the
intellect.
3. The intimate association between the specifying activ­
ity of the intellect and the exercise of will is precisely what
characterizes St. Thomas’ doctrine of freedom. For him, free
choice is a matter of intellective appetite, appetitus intellec­
tivus. Opposed to the free act is the act born of a necessitating
inclination.

G
GENERATION.—Substantial change terminating in a new
substance. [It is not improper, however, to speak of “acciden­
tal generation” as well]. See Corruption.
GENUS.—Universal expressing, though only in part, the essence
of its inferiors; ex. “animal.” One of the five predicables.
GOOD.—1. Being itself, considered as capable of fulfilling a
desire, or under the aspect of perfection. Good is what all
things desire. Like one and true, good is a transcendental
property of being.
2. Threefold division {honestum, utile, delectabile'). Right­
eous good: that which is sought for its own sake, or for its
own goodness. Useful good: that which is sought purely as a
means, or for the sake of something else. Pleasant good: the
enjoyment that attaches to the attainment of a good.
H
“HABITUS.”—1. Metaphysics. Possession: the fact that what
the subject is provided with is on the subject but wholly ex­
trinsic to it; ex. “to be clothed.” Habitus is the tenth, and last,
predicament given by Aristotle.

308
Glossary of Technical Terms
2. Psychology, Moral Philosophy. That by which a subject
is well- or ill-disposed with respect to its form or end. Habitus
and disposition make up the first species of quality.
3. Basic division. Entitative habitus: pertains to being; ex.
grace. Operative habitus: the more common type; that by
which the subject is immediately disposed to act; ex. the
virtues.
4. Note. The vernacular “habit” denotes rather the manner
of the act, necessarily implying, it would seem, a degree of
mechanicalness and repetition. It has therefore a more spe­
cialized and more restricted meaning than “habitus.”
HYLOMORPHISM.—Physical doctrine according to which
bodies are ultimately composed of the two principles of mat­
ter and form. Distinctive of Aristotelian cosmology and op­
posed, above all, to atomism.
HYPOTHETICAL.—1. Hypothetical propositions are com­
pound propositions formed from simple propositions joined
by copulas (“and,” “if,” “or”) other than the verb “to be.”
2. In the hypothetical syllogism the major is an hypotheti­
cal proposition, and the minor posits or sublates (denies) one
of the members of the major.
I
IDEA.—Exemplar (form) in the mind of the maker according
to which a thing is made. In St. Thomas the word “idea” is
reserved to the divine exemplar; thus its meaning is not the
same as in contemporary psychology.
IDENTITY.—1. In precise sense, the unity of substance.
2. Principle of identity. One of the first principles of
thought.
IMAGINATION.—Faculty which conserves and reproduces
images, i.e. presentations of the outer senses. One of the four
inner senses.

Glossary of Technical Terms
309
IMMANENT.—That which remains in the subject. Immanent
action terminates in the acting subject and perfects the sub­
ject itself. Immanence is the distinctive mark of vital opera­
tions. Opposed to transeunt action, which terminates in an­
other and perfects the other.
IMPOSSIBLE.—That which cannot be, or which involves
contradiction. Opposed to possible.
INDIVIDUAL.—1. Logic. Ultimate subject, in no way predi­
cable. The species comprises the individuals.
2. Metaphysics. In the sense of supposit: being as endowed
with its own incommunicable subsistence.
INDUCTION.—In general, reasoning from the particular to
the universal.
INSTRUMENTAL (CAUSE).—Cause which acts according
to the power of its own form but as moved by another (the
principal cause).
INTELLECT [intellectus, intelligentia],—1. Designates, most
often, the spiritual faculty of knowledge (in more modern
terminology, usually “intelligence”).
2. Agent intellect. Faculty which abstracts the intelligible
species from sense images.
3. Passive or possible intellect. Faculty which receives the
abstracted likeness (species).
4. Intellectus (understanding). The term for the intellec­
tual habitus (virtue) which perfects the intellect in its grasp
of first principles.
INTELLECTION.—The act by which the intellect apprehends
its object, or knows. Differentiated from diction (expression),
the act that produces the mental word in which the object
is known.
INTELLIGIBLE.—That which can be immediately appre­
hended by the intellect. In Aristotelian doctrine, intelligibility
is a function of immateriality.

jio
Glossary of Technical Terms
INTENTION.—i. Moral Philosophy. Orientation of a tend­
ency, and in particular of the will, towards its end.
2. Psychology. Tire concept as ordered to represent an ex­
ternal thing.
3. Logic. Second intentions (in contrast to first intentions):
the concept as a logical being of reason, or as emanating from
the activity of the mind only.
4. Intentional order. The order of representation, or of
objects as they exist in thought (and in knowledge generally).
INTUITION [intuitus, perceptio].—Designates, regularly, the
experimental grasp of a concrete object. Opposed to concep­
tion, which corresponds rather to the abstractive mode of
knowledge, or to the formation of a concept.
IRASCIBLE (APPETITE).—One of the two faculties of sensi­
ble appetition; its object is the difficult (to attain) good or
the difficult (to avoid) evil.
J
JUDGMENT.—1. In the general sense, act of the intellect
which corresponds to the second operation of the mind.
2. In the strict sense, judgment [judicium) in St. Thomas
is not any judgment whatever but one which serves to termi­
nate a deliberative state of affairs in the order of wisdom; e.g.
a decree handed down by a judge.
3. When referring to the second operation of the mind in
all its generality, St. Thomas regularly employs the expression
compositio vel divisio, the act of the intellect which composes
or divides, i.e. affirms or denies.
L
LIFE.—1. Spontaneous and immanent activity, proper to living
things.
2. Principal degrees of life: vegetative, sensitive, and intel­
lective.

Glossary of Technical Terms

311

M
MAJOR.—In the categorical syllogism, the premise containing
the major term.
MATTER.—1. That of which a thing is made as of an imma­
nent principle. Matter and form are the intrinsic principles
of physical being.
2. Prime (first) matter: first and absolutely undetermined
subject which, with substantial form, constitutes the substan­
tial nature of bodies.
3. Second matter: subject in which accidental forms or de­
terminations of corporeal substances are received.
4. Intelligible, sensible, individual matter: matter as ab­
stracted in varying degree (intelligible, sensible), or not at all
(individual).
MEMORY.—Faculty which evokes nonsensible perceptions so
far as they refer to the past. One of the four inner senses.
According to St. Thomas there is no intellectual memory that
would be distinct from the intellect itself.
“MENS” (MIND).—The human soul as principle of its spiri­
tual operations, namely intellection and volition.
MIDDLE TERM.—In the syllogism, the term common to both
premises.
MINOR.—In the syllogism, the premise containing the minor
term.
MIXTURE.—In Aristotelian cosmology, body resulting from
the composition of several elementary substances and con­
stituting a single new substance in place of the several original.
MODALITY. —1. Property of propositions expressing the man­
ner in which the predicate applies, or does not apply, to the
subject (in the manner: possible, impossible, necessary, or
contingent).
2. Modal proposition: one in which the mode is explicitly
stated.

312
Glossary of Technical Terms
3. Modal syllogism: one in which at least one premise is a
modal proposition.
MODE.—In general, anything that determines or modifies a
being.
MOOD.—Logic. Disposition of the syllogism resulting from the
quantity and the quality of each premise.
MOTION.—1. Metaphysical definition: the act of what is in
potency as such, or precisely as in potency.
2. Division. Besides substantial change, which is not strictly
a motion, Aristotle distinguishes three types of motion proper:
a) local motion, b) qualitative alteration, and c) quantitative
augmentation and diminution.
MOTIVITY.—Function in virtue of which animals move them­
selves locally. Presupposes a special faculty, the locomotive
power.
MOVABLE.—That which is moved. The movable is the sub­
ject of motion.
MOVER.—1. The active principle of motion. Opposed to
movable, the subject of motion.
2. Prime (first) mover. In Aristotelianism, ultimate prin­
ciple of physical motion, reductively pure act, God.
N
NATURE.—1. Physics. In a physical being, the intrinsic prin­
ciple of its motion and rest. Nature, as a principle of opera­
tion, is opposed to art, an extrinsic principle and, moreover,
of the rational order.
2. By extension, nature designates the sum total of physical
beings, the physical universe.
3. The meaning of nature is further enlarged to signify the
essence of any being, even of the purely spiritual.
4. From the standpoint of intelligible content, nature cor­
responds to form and essence.

Glossary of Technical Terms
313
NECESSARY.—That which cannot not-be. Opposed to con­
tingent, that which can not-be.
NOUN.—The noun is a term signifying nontemporally. Noun
and verb (the latter always connoting time) are the necessary
and sufficient elements of enunciation.
NUMBER.—A species of quantity. Definition: a multitude
measured by the unit. Numerical multitude and unit must be
distinguished from transcendental multitude and unit. See
One.
O
OBEDIENTIAL (POTENCY).—Designates the aptitude of a
nature to receive, by power of a superior agent, a determina­
tion surpassing its natural capacities. Creatures are in obedi­
ential potency with respect to God, the supreme agent.
OBJECT.—1. That which is directly attained by a power and
determines it.
2. Formal object: that aspect of a thing which constitutes
the specific attainment of a power or faculty.
3. Material object: the thing attained, considered in its
whole reality.
ONE.—1. Transcendental one. Designates the undividedness of
being as being. A transcendental property of being.
2. Predicamental one. The unit as principle and measure
of number.
3. Opposed, either sense, to the many.
OPPOSITION.—1. In general, the relation of exclusion be­
tween two things or two forms.
2. The four modes of opposition: opposition of relatives,
of contraries, of privation and possession, of contradiction.
3. Opposition of propositions. Relations of exclusion be­
tween propositions having the same subject and predicate but
varying as to quantity or quality or both.

314

Glossary of Technical Terms

P
PARTICIPATION.—i. The fact of having part in a form.
2. There are two basic types of participation. By composi­
tion: when a subject receives a form which in its source sub­
sists by itself. By similitude or likeness: when a form is only
imperfectly what another form on which it depends is per­
fectly or in fullness.
PARTICULAR.—i. A term taken only according to part of its
extension; e.g. “some man.”
2. Particular proposition. One in which the subject is a
particular term.
PASSION.—i. The fact of being modified or of undergoing a
change of some kind. One of the ten predicaments.
2. Moral philosophy. Passions, in this more special sense,
designate the various modifications of the sensible appetite.
PATIENT.—That which undergoes a modification. Motion is
founded in the patient (rather than the agent).
“PERSEITY.”—Property of that which exists by itself, namely
of substance. N.B. In this sense “per se” never has causative
implication.
PERSON [persona, hypostasis].—Rational, subsistent, individ­
ual substance; “supposit,” as understood of the rational being.
PHANTASMS [phantasmata].—Term regularly employed by
St. Thomas for sense images, especially as point of departure
for intellectual abstraction.
PLACE.—i. Physics. Terminus or limit of the containing body,
this terminus being immovable when considered in relation
to a first container which, as such, is necessarily immovable.
2. Local motion. Motion relative to place.
3. Natural place. In Aristotelian cosmology, the place to­
ward which a given element naturally tends and in which it
comes to rest; ex. the upper region for fire, etc.

Glossary of Technical Terms
315
4. Logic. The commonplaces (loci communes'): universally
accepted general principles which govern a course of argu­
mentation.
POSSIBLE.—That which can be, or which is free of intrinsic
contradiction. Opposed to impossible: that which cannot be.
POTENCY.—1. Any capacity for change or determination.
Typified by relation to act; hence is defined as “that which
can be but is not as what is in act.”
2. Principal divisions. Active potency: the potency to
change another as other. Passive potency: the potency to be
changed by another as other. Natural potency: such as is
found in a thing by reason of its nature. Obediential potency:
aptitude of a being to receive from a higher agent a determina­
tion surpassing its nature; e.g. supernatural grace.
3. Potency and act are primary divisions of real being.
PRACTICAL.—1. In precise psychological and logical termi­
nology, designates that which pertains to action as against
that which refers to pure contemplation; used in this sense in
practical intellect and practical sciences.
2. In more restrictive use, the term “practical” designates
the order of moral activity, the agibile, as distinct from the
order of making, the factibile.
PREDICABLES.—Logic. A group of universal concepts dis­
tinguished according to their relation to the inferiors of which
they can be predicated. There are five predicables: genus,
species, difference, property, accident.
PREDICAMENTS.—Synonymous with Categories, q.v.
PREDICATE.—See Attribute.
PREMISES.—The first two propositions of a syllogism. The
premises constitute the antecedent, from which is drawn the
consequent.
PRINCIPLE.—Id unde. . . . That from which a thing begins
to be made or to be known; hence, that from which some­

ji6
Glossary of Technical Terms
thing proceeds in any manner whatever. “Principle” is a wider
term than “cause,” which implies, additionally, real depend­
ence of being on the part of the thing made. Every cause is a
principle, but not every principle a cause.
PRIVATION.—i. Absence of a perfection which by nature a
being should have; e.g. blindness. The privation-possession
relation typifies one kind of opposition.
2. Cosmology. Privation is one of the principles of mobile
(physical) being.
PROPERTY [proprietas, proprium].—That which necessarily
flows from the essence of a thing. The property [proprium)
which denotes the characteristic quality or trait of a given
essence is one of the five predicables.
PROPORTIONALITY.—Analogy of proportionality: one kind
of analogy. See Analogous.
PROPOSITION.—i. Verbal expression of a judgment com­
prising essentially two terms, subject and predicate, joined by
a copula.
2. Principal divisions. As to quality: affirmative and nega­
tive; as to quantity: universal, particular, singular.
PRUDENCE.—A habitus or virtue whose function it is to
direct human action according to right reason in the realm of
the contingent. One of the five intellectual virtues.
Q
QUALITY.—i. Accident intrinsically modifying substance, or
disposing it in itself. One of the ten predicaments.
2. The four species of quality: a) disposition and habitus;
b) potency and impotency, c) passible qualities, d) figure and
form.
3. Logic. Property of propositions according to which they
are affirmative or negative.

Glossary of Technical Terms
317
“QUANDO” [lit. “when”].—Designates the predicament said
of time. Signifies the exact temporal circumstance; ex. yester­
day.
QUANTITY.—1. Accident consisting essentially in the internal
divisibility of a body and in the extension of its parts.
2. Division. Continuous or concrete, the quantity of mag­
nitude; discontinuous or discrete, the quantity of number.
3. Logic. Property of terms corresponding to their extension
(universal, particular, singular). By derivation, property of
propositions corresponding to the extension conferred on the
subject.
“QUIDDITAS.”—Translated “quiddity” (“whatness”). Liter­
ally, that which answers to the question quid sit, “what is it?”
Expresses the essence or the definition of a thing.

R
REASON.—1. Psychology. Intelligence considered in its dis­
cursive function; opposed to intellectus (understanding),
which is intelligence considered more specially as power of
intuition.
2. Being of reason. That which, as such, can only exist in
the mind. Opposed to real being.
3. “Ratio” (in the sense of such expressions as “ratio entis,”
“ratio veri,” etc.) designates a formal or objective principle
of a thing but as explaining or giving the reason of it. The
vernacular “reason,” though hard to better, is in this instance
a very inadequate rendition of the Latin.
4. Principle of sufficient reason. One of the prime laws of
thought.
REASONING [ratiocinatio, argumentatio].—Act of the intel­
lect which consists in going from one thing to another in such
a way that from knowledge of what is known we come to

318
Glossary of Technical Terms
knowledge of what was unknown. Constitutes the third oper­
ation of the mind.
RELATION [relatio, ad aliquid].—i. In general, how one thing
stands in regard to another: ad aliud.
2. Transcendental relation. Essential order of one thing to
another; ex. order of the intellect to the true.
3. Predicamental relation. Accident of which the whole
reality consists in “towardness” or reference to another; e.g.
relation of likeness. One of the ten predicaments.
S
SCIENCE.—1. In strict Aristotelian doctrine, signifies knowl­
edge through causes. Subjectively, science is one of the five
speculative virtues (habitus).
2. Division. Speculative science: whose only end is knowl­
edge. Practical science: which is ordered to action.
SENSE.—1. Power or faculty of knowledge whose act is sensa­
tion and which utilizes a corporeal organ.
2. Division. Five outer senses; four inner senses (common
sense, imagination, memory, cogitative or, in the animal,
estimative).
SENSIBLE.—1. The object of sensory powers.
2. Distinctions. Proper object (or sensible): that which is
apprehended immediately and as such (color, by sight). Com­
mon object: apprehended by more than one sense (magni­
tude). Accidental [per accidens) object: perceived indirectly
only, by medium of a proper object (a man, by sight).
SIGN.—1. That through which another thing becomes known.
2. Natural sign. Based on a natural connection between
sign and signified.
3. Conventional sign. When the connection with the thing
signified comes from human choice or agreement.

Glossary of Technical Terms
319
SIMILITUDE [similitudo, species],—1. The similar designates
the mode of unity pertaining to quality.
2. Psychology. Similitude, likeness, or “species”: represen­
tation whereby an external thing is rendered present to intel­
lect or sense.
SINGULAR.—1. Term whose extension is reduced to a single
individual.
2. Singular proposition. A proposition with a singular term
as subject.
SITUATION [situs].—Disposition as to place of the parts of
a body. One of the ten predicaments.
SOUL.—1. The first immaterial principle of life. In Aristotelian
doctrine, the soul is the substantial form of the body it
animates.
2. Vegetative, sensitive soul. Principles, respectively, of
plant and animal life.
3. Rational soul. Principle of rational or spiritual life,
proper to man. Also exercises the functions of the vegetative
and sensitive soul, whose place it takes.
“SPECIES.”—See Similitude.
SUBJECT.—1. Logic. That of which something is affirmed or
denied in a proposition. Opposed to predicate.
2. In science, the thing of which the properties are deter­
minded; e.g. number, subject of arithmetic.
3. Psychology. That which knows, as against that which is
known, the object.
4. Metaphysics. In general, that which receives form. On
this score, matter is subject.
SUBSISTENCE.—Substantial mode terminating the essence
and rendering it incommunicable. According to the foremost
commentators of St. Thomas, subsistence is really distinct
from essence and from existence.

^20
Glossary of Technical Terms
SUBSTANCE.—i. That which has the aptitude to exist in
itself and not in another. One of the ten predicaments. Op­
posed to accident.
2. First substance. The concrete, individual subject; e.g.
Peter.
3. Second substance. Abstract essence of the subject; e.g.
“man.”
SUPPOSIT.—The substantial, subsistent individual. If a ra­
tional being, supposit is called “person.”
SYLLOGISM.—1. Logical form of deductive reasoning. A dis­
course in which, certain things being given, something other
than the given necessarily follows from the given.
2. Division. Categorical, hypothetical syllogism. See Cate­
gorical, Hypothetical.
T
TERM.—1. Verbal expression of a concept; corresponds to the
first operation of the mind.
2. Physics. End point of a motion.
THEORETICAL.—That which is purely an object of specula­
tion (i.e. contemplation). Opposed to practical. In phrase:
theoretical (speculative) sciences.
TIME.—The measure of motion according to before and after.
Differs from eternity and eviternity or the aevum. Eternity:
perfect and simultaneous possession of life without beginning
or end. Eviternity: the ceaseless, nonsuccessive duration of
spiritual substances.
“TOPICS” [TOPICA].—One of the books of the Organon of
Aristotle; treats in particular of “commonplaces,” i.e. com­
monly acknowledged propositions which govern probable
reasoning or argumentation.
TRANSCENDENTALS.—1. In Aristotelian use, that which is
above (in the sense of not restricted to) any genus.

Glossary of Technical Terms
321
2. Transcendental properties. Those which pertain to being
as being, hence are found in all its modes. Basically three: the
one, the true, the good.
TRUTH.—1. In general, conformity between intellect and
thing.
2. Logical truth. Conformity of the intellect to the thing it
knows. Occurs, formally speaking, in the second operation of
the mind only, i.e. in judgment.
3. Ontological (transcendental) truth. Property of every
being, namely its conformity to the intellect that is its prin­
ciple, the creative intellect.

U
“UBI” [lit. “where”].—Term designating the predicament place.
See Place.
UNIVERSAL.—1. Term or concept taken in all its extension.
2. Controversy about Universals. Specifically, the discus­
sion among medieval Scholastics concerning the validity of
universal concepts.
UNIVOCAL.—Property of a term or concept which is said of
its inferiors according to a meaning absolutely identical in
each case; e.g. “man.” Opposed to analogous and equivocal,
q.v.
V
VEGETATIVE (LIFE).—Totality of lower vital functions
common to all living things in nature; namely nutrition,
growth, reproduction.
VERB.—Logic. Word in a proposition signifying action or pas­
sion with a necessary reference to time.
VIOLENT.—1. That which is counter to the natural inclina­
tions of a being.

■^22
Glossary of Technical Terms
2. Violent motion. That which goes contrary to such nat­
ural inclinations.
W
WILL.—Rational appetite, or appetite which follows on intel­
lectual knowledge. Its object is the good apprehended by the
intellect. See also Free Will.
WISDOM.—Knowledge of things by their highest and most
universal causes. Subjectively, one of the five intellectual vir­
tues (habitus). In the natural order, pre-eminently meta­
physics.
WORD (MENTAL).—The concept (or interior term of the
intellectual act) in which the intellect contemplates its object.
Synonym: “expressed species.”

t

Index

three degrees of, 1821
Accidents
in metaphysics, 245-248 (Text
Il B)
meaning of, 169-170
schematic presentations of, 170!73
Act
divisions of, 192-195
entative, 192, 193
explication of, 267-269
immanent, 193
in Aristotle, 191
in Thomas Aquinas, 191
meaning of, 191—192
mixed, 192-193
operative, 192, 193
pure, 192, 193
transeunt, 193
Act and potency
as the cardinal principles of
Thomistic metaphysics, 198200
in Aristotle, 183-185
in Heraclitus, 184-186
in Parmenides, 184-186
relation of, 193-198

abstraction,

Ambrose, St., and the kinds of
good, 145
Analogous concept, unity and ab­
straction of, 57-61
Analogy
division of, 52-56
in Aristotle, 63
in Cajetan, 48, 52
in Duns Scotus, 48-49
in John of St. Tilomas, 48
in Suárez, 49
in Sylvester of Ferrara, 61
in Tliomas Aquinas, 50-51, 6264
of attribution, 52-54, 66-67
of being, 64-71
of proportionality, 54, 66-67
order and principle in, 61—64
the doctrine of, 47-64
the meaning of, 49-52
Anaxagoras, and the doctrine of
separation, 16
Anaximenes, and the primordial
element, 22
Andronicus of Rhodes, and meta­
physics, 1
Aquinas, St. Thomas; see Thomas
Aquinas, St.

Index

324
Aristotle
and accidents, 170
and act and potency, 185-185
and metaphysics of being, 24
and order and principle in anal­
ogy, 63
and quality, 173
and realism, 103
and skepticism, 83
and the division of act, 192
and the division of potency,
189-190
and the doctrine of separation,
16-17
and the first principles, 106-107
and the individuation of material
substance, 167
and the one, 128, 130
and the real distinction, 203
and the true, 134
and transcendentals, 122
and wisdom, 5-6, 13, 15
on act, 191
on causality, 216-218
on substance, 157, 161-163
on the nature of good, 142-143
schematic presentation of the ac­
cidents, 173
the metaphysical work of, 29—33
Augustine, St., and the true, 134-

Averroes, and the real distinction,
212
Avicenna, and the real distinction,
212
BEING

accidental, 257-258 (TextV A)
analogy of, 64-71
essential, 257-260 (Text V A B)
in Duns Scotus, 64
in metaphysics, 244-249 (Text
II)

(continued)
in Thomas Aquinas, 73, 120-121
meaning of, 277-278 (Text XII
A)
metaphysical notion of, 38-44
necessity of God’s creating every,
291-293 (Text IV)
notion of and the metaphysical
method, 67-72
principle modes of, 256-260
(Text V)
the structure of the notion of,
44-47
Bergson, and the starting point of
metaphysics, 35
Boethius, and the real distinction,
204
British Empiricists, and realism, 95
Brunschvieg, and realism, 81
being

CAJETAN

and the division of analogy, 52
and the doctrine of analogy, 48
and the problem of subsistence,
168
Causality
and Thomas Aquinas, 228-229,
critical justification of, 223-229
Five Ways of Thomas Aquinas,
218-223
in Aristotle, 216-218
in Kant, 224
in scientific explanation, 216-218
in the British Empiricists, 223
in the Cartesians, 223
in the Nominalists, 223
in theology, 218—233
in Thomas Aquinas, 217-218
principle of, 117, 225-229
the experience of, 224-225
the First Cause, 229-233

Index
Cogito
and realism, 87, 90
and reality, 97-99
“Copernican Revolution,” 28

Democritus, and realism, 79
Descartes
and indubitable knowledge, 27
and realism, 74, 76-77, 87, 88,
95’ 97-99
and the metaphysical method, 69,
71
and the real distinction, 212
Distinctions
logical, 127
verbal, 127
Doctrine of separation
in Plato, 17
origins of, 16-18
Duns Scotus
and the doctrine of analogy, 4849
and the metaphysical method, 69
and the notion of being, 64
and the real distinction, 205

see also essence and ex­
istence
in composite substances, 278279 (Text XII B)
in God, 287-291 (Text XIII)
in separate substances, 279-284
(Text XII C)
meaning of, 277-278 (Text XII
A)
three ways found in substances,
284-287 (Text XII D)
Essence and existence
Aristotle on the real distinction,
203
Boethius on the real distinction,
204
composition of created substances

essence;

325
Essence and existence (continuad)
and the simplicity of uncreated
being, 209-211
Duns Scotus and the real distine
tion, 205
Giles of Rome and the real dis
tinction, 205
Henry of Ghent and the real dis
tinction, 205
historical sketch of the problems
of distinction, 203-205
originality of Thomas Aquinas’
doctrine, 211-213
problem of the real distinction,
201—203
proofs of the real distinction,
203—207
Suárez and the real distinction,
205
Thomas Aquinas on the real dis­
tinction, 205—206
true sense of the real distinction,
207-209
Excluded middle, law of, 117
Existence; see also essence and ex­
istence
in God, 287-291 (Text XIII)
Epicurus, and realism, 79
Epistomology, Thomist, 82—96
Evil
as an opposite of good, 146-147
in Thomas Aquinas, 146

the, 138-139
Fichte, and realism, 80, 96
Finality, the principle of, 117, 147149
First principle of demonstration,
252-254 (Text IV)
First principles
and Aristotle, 106-107
definition, 107-108
order of, 108-109, 116-117

false,

Index

326
First principles (continued)
origin and formation of, 117-118

on the princi­
ple of identity, 115, 116
Giles of Rome, and the real dis­
tinction, 205
Gilson
and realism, 90-91, 93
and the real distinction, 211
God is life, 269-270 (Text VIII)
Good
and St. Ambrose, 145
as adding to being, 274-276
(Text XI)
as final cause, 144-145
in Aristotle, 142-143
in Thomas Aquinas, 143, 144
kinds of, 145-146
nature of, 142-144

garrigou-lagrange,

John of st. thomas, and the doc­
trine of analogy, 48
Judgment
elements of, 99-103
the realist import of, 103-106
KANT, IMMANUEL

and causality, 224
and realism, 80, 81, 88, 96
and the real distinction, 212
Knowledge
activity of, 85-86
immanence of, 83-85

Leibnitz, and sufficient reason, 139
Logical truth, in Thomas Aquinas,
136-137
Lombard, Peter, and the transcendentalists, 123
MARITAIN, JACQUES

Hamelin, and realism, 78-80
Hegel
and realism, 80, 96
and the metaphysical method,
69,72
and the real distinction, 212
Henry of Ghent, and the real dis­
tinction, 205
Heraclitus
and act and potency, 184-186
and the primordial element, 22

see realism
Identity
the principle of, 113-118
the principle of and Thomas
Aquinas, 113-114
the principle of in GarrigouLagrange, 115, 116
the principle of in Maritain, 115116

idealism;

and realism, 90
on the principle of identity, 115116
Measure, as a property of the unit,
1 31
Metaphysical method
in Descartes, 69, 71
in Duns Scotus, 69
in Hegel, 69, 72
in Plato, 69, 71
in Spinoza, 72
in Suárez, 69
in Thomas Aquinas, 69, 71
Metaphysics
and critique of knowledge, 25-29
as a science, 238-243 (Text I)
historical derivation, 22-24
in Bergson, 35
in Parmenides, 36-37
in the Physicists, 37
in Plato, 37

Index
Metaphysics (continued)
of being, 21-25
of being in Aristotle, 24
of being in Plato, 23-24
the starting point of, 35-38
Thomas Aquinas on, 35-36
Multiplicity, 133-134
and realism, 88
Noncontradiction
formulation of the principle, 109110
steps by which the mind becomes
cognizant of, 110-111
the principle of, 109—113
validity of, 111-113

noel,

ONE, THE

and Aristotle, 128, 130
and Parmenides, 128
and Plato, 128
as principle of number, 270-272
(Text IX)
as transcendental, 270-272 (Text

. IX>

in Thomas Aquinas, 129—131
Pythagorean theory on, 128
study of in metaphysics, 249-251
(Text HI)
PARMENIDES

and act and potency, 184-186
and the notion of being, 22, 23
and the one, 128
and the starting point of meta­
physics, 36-37
Physicists, and the starting point of
metaphysics, 37
Plato
and the doctrine of separation, 17
and realism, 95
and the metaphysical method,
69,71

327
Plato (continued)
and the metaphysics of being,
23-24
and the one, 128
and the starting point of meta­
physics, 37
and wisdom, 6
Plotinus, and wisdom, 6
Potency
active, 189-190
division of, 189-190
explication of, 264-267 (Text
VII A)
meaning of, 187-188
natural, 189-190
nonrational, 189-190
obediential, 189-190
passive, 189-190
rational, 189-190
Proportionality
metaphorical, 55-56
proper, 55-56
Pythagoras, and the first principle, 23
QUALITY

Aristotle on, 173
nature of, 173-175
the species of, 175-177
Quantity, in contrast to quality,
Í74-Í75

see essence and
existence
Realism
and Aristotle, 103
and Brunschvieg, 81
and Descartes, 74, 7^“77> ®7> 88,

real distinction;

95’ 97-99
and Democritus, 79
and Epicurus, 79
and Fichte, 80, 96
and Gilson, 90-91, 9 3

Index

328
Realism (continued)
and Hamelin, 78-80
and Hegel, 80, 96
and Kant, 80, 81, 88, 96
and Maritain, 90
and Noël, 88
and Plato, 95
and Roland-Gosselin, 87-88, 99,
101, 103
and Schelling, 96
and the British Empiricists, 95
and the Skeptics, 74
and the Sophists, 74
and Thomas Aquinas, 89, 103
authentic function of, 96-105
critique of, 74-82
Thomist, 86-94
Relation
predicamental, 178-181
transcendental, 177-178
Roland-Gosselin, and realism, 8788, 99, 101, 103

Schelling, and realism, 96
Skepticism, and Aristotle, 83
Skeptics, and realism, 74
Sophists, and realism, 74
Spinoza, and the metaphysical
method, 72
Suárez
and the doctrine of analogy, 49
and the metaphysical method, 69
and the real distinction, 205
Subsistence, the problem of, 168—
169
Substance-accident composite, unity
of, 165-166
Substance
divisions of, 163-165
existence of, 154-159
first, 163
immaterial, 163, 164-165

Substance (continued)
in metaphysics, 245-249 (Text
II AB), 260-263 (TextVI)
individuation of material sub­
stance, 166-167
material, 163-164
principle of, 117
problems regarding, 165-169
second, 163
six marks of, 161-163
Sufficient reason
and Leibnitz, 139
in Thomas Aquinas, 139-142
principle of, 117, 139-142
Sylvester of Ferrara, and order and
principle in analogy, 61
THOMAS AQUINAS, ST.

and being, 73
and order and principle in anal­
ogy, 62-64
and realism, 89, 103
and the definition of analogy,
50-51
and the distinction of act and
potency, 195, 197
and the false, 138
and the metaphysical method,
69,71
and the modes of unity, 131
and the principle of identity, 113114
on act, 191
on causality, 217-218, 228-229,
233
on evil, 146
on logical truth, 136-137
on metaphysics, 2-4, 28
on multiplicity, 134
on sufficient reason, 139-142
on the derivation of being, 120121

Index
Thomas AguiNAS, st. (continued)
on the individuation of material
substance, 167-168
on the nature of good, 143
on the one, 129-131
on the principle of finality, 148
on the real distinction, 205-206
on the starting point of meta­
physics, 35-36
on the transcendentals, 124-125,
126-127, 150-152
on wisdom, 13, 15-16
schematic presentation of the ac­
cidents, 170-171
the metaphysical work of, 29-33
Thomas, John of St.; see John of
St. Thomas
Transcendentals
and Aristotle, 122
and Peter Lombard, 123
as a system, 149-151
derivation of, 121—126
in Thomas Aquinas, 124-125,
126-127, 150-152
nature of, 126-128

329
Transcendentals (continued)
the one, 128-134
Tree of Porphyry, 40, 163
True, the
and Aristotle, 134
and St. Augustine, 134-135
Truth
logical, 135-137, 272-274 (Text
X)
ontological, 135, 137-138, 272274 (Text X)

the modes of and Thomas
Aquinas, 131

unity,

WISDOM

in Aristotle, 5-6, 13, 15
in Plato, 6
in Plotinus, 6
in relation to science and under­
standing, 9-14
metaphysics as, 5-16
the excellence of, 14-16
the several kinds of, 5-9
Wolff, and the real distinction, 212