BT THE SAME AUTHOR
THREE REFORMERS
LUTHER—DESCARTES'—ROUSSEAU

PRAYER AND INTELLIGENCE
TRANSLATED BY ALGAR THOROLD

ART AND SCHOLASTICISM
TRANSLATED BY J. F. SCANLAN

AN INTRODUCTION TO
PHILOSOPHY

BY

JACQUES MARITAIN

TRANSLATED BY

E. I. WATKIN

LONGMANS, GREEN AND CO.
55 FIFTH AVENUE • NEW YORK

I931

Mt. Angel Abbey Library
St. Benedict, Oregon 97373

0L>
3 It

Made and Printed in Great Britain by
Haxellt Watson & Viney, Ltd,, London and Aylesbury.

PUBLISHER’S NOTE
The French edition of this work, under the title Introduction
Générale à la Philosophie, appears as the first volume of
seven, which deal with Formal Logic, Theories of Knowledge,
Cosmology, Psychology, Metaphysics, Ethics, Æsthetics, and the
History of Philosophy. But, since six out of the seven volumes
remain to be written, it has been thought better to issue the present
volume quite independently.
The series as a whole is intended to provide text-books for a
regular university course as it is found in France, and with that
particular end in view prints in larger type those paragraphs
which the student should read first, and in smaller type those
paragraphs which are merely explanatory or expansive of them.
This schematising has been abandoned to make the volume serve
for general readers, no university course being envisaged in England
or America.
The translation has been made from the eleventh French edition.

5

PREFACE
My chief aim in composing an Elements of
Philosophy series, to which this book may serve as
an introduction, is to give a faithful presentation of
the system of Aristotle and St. Thomas, and in its
light to judge the important systems which have
followed each other during the last three centuries
and the principal problems discussed by modern
philosophy. I have tried to adapt the method of
exposition to contemporary conditions, and in parti­
cular have followed of set purpose a progressive order
of exposition—as far as possible the order of intellectual
discovery—never appealing to any truth not already
known and understood, and never introducing a
new notion or proposition for which the way has not
been prepared by those which have gone before it
and led up to it. The method has obliged me to
depart on several points from the procedure of the
traditional text-books—above all, considerably to
magnify the importance and extend the scope of this
Introduction. Yet, thus, I have but returned to the
method followed by Aristotle himself. The first three
books of his Metaphysics are, in fact, nothing but an
extensive introduction.
A work of this kind, if it is to be thorough, demands
the detailed discussion of certain points, without which
the study it seeks to promote would lose all its value
as a mental discipline. I should be untrue to tradi­
7

PREFACE

tional philosophy if I reduced it to a few main theses
which have lost their freshness, and a few common­
places of a spiritualist metaphysic, and neglected to
bring out its fine intellectual contours and display its
power of penetrating analysis.
The present work is intended for beginners. It
can therefore make no attempt to reproduce the
depth or the wealth of subtle dialectic to be found in
treatises written for specialists, and remains strictly
elementary. It must, however, preserve the scientific
character proper to a philosophical exposition.
Some readers may take alarm at scholastic termino­
logy. Yet no science, no discipline, no form of sport,
even, or industry, can dispense with a special termino­
logy—often far more arid and artificial than the
vocabulary of philosophy. To require that philo­
sophers should use everyday language implies that
their science is just an enterprising topic of conversa­
tion, idle arm-chair speculation for after dinner. On
the other hand, it may legitimately be demanded
that no technical term be used until it has been
clearly defined.
Finally, I would say that, if the philosophy of
Aristotle, as revived and enriched by St. Thomas
and his school, may rightly be called the Christian
philosophy, both because the Church is never weary
of putting it forward as the only true philosophy
and because it harmonises perfectly with the truths of
faith, nevertheless it is not proposed here for the
reader’s acceptance because it is Christian, but because
it is demonstrably true. This agreement between a
8

PREFACE

philosophic system founded by a pagan and the dogmas
of revelation is no doubt an external sign, an extraphilosophic guarantee of its truth ; but it is not from
its agreement with the Faith, but from its own
rational evidence, that it derives its authority as a
philosophy.
Nevertheless, reason and faith, while distinct, are
not separate, and, since I am writing principally for
Christian readers, I have not denied myself an occa­
sional reference to knowledge familiar to every
Catholic, or to certain theological applications of
philosophic principles, the better to put philosophy
in its proper place in Christian minds, or to help them
to maintain the unity of their thought. The fact
remains that in our arguments and in the very structure
of our exposition of philosophy, it is not faith, but
reason, and reason alone, which occupies the entire
ground and holds undivided sway.

9

CONTENTS
PAGE

INTRODUCTORY .

.

.17

PART ONE
THE NATURE OF PHILOSOPHY
PHILOSOPHIC THOUGHT BEFORE PHILOSOPHY IN
THE STRICT SENSE .

Introduction
Primitive tradition
The Semites and the Egyptians
The Indo-Europeans :
(a) The Persians .
(è) The Indians : .
(i) Brahmanism .
(ii) Buddhism
(iii) Other schools
(c) The Chinese
Limitations of human wisdom
The Greeks the chosen people of reason
II.

46

THE PRE-SOCRATIC PHILOSOPHERS

The Sages
The lonians : .
(a) Thales and his successors
(è) The great physicists :
(i) Heraclitus
(ii) Democritus .
(iii) Anaxagoras .
The Italians : Pythagoras .
The Eleatics : Parmenides .
II

23

23
24
25
26
26
27
28
33
36
38
42
44
46
47
48

50

50
52
54
55
60

CONTENTS
III.

THE SOPHISTS AND SOCRATES ....

Introduction ....
The sophists
....
Socrates .....
(a) Ethics and knowledge
(IP) Irony, maieutic, dialectic .
(c) Moderate intellectualism .
IV.

DEFINITION OF PHILOSOPHY

•
•
•
•
.
.
•
•
•
•
•

74
75
75
78
81
82
83
87
92
97
99

74

102

.

Scientific knowledge .
Its material object
Its formal object
Conclusion I
Further considerations
VI.

64
65
68
69
70
72

PLATO AND ARISTOTLE .

The minor Socratics .
Plato
.....
(a) His theory of ideas .
(¿) His system of philosophy .
(c) Its limitations .
Aristotle .....
(a) Corrections of Plato .
(¿) The Aristotelian system
(c) Aristotle’s works
Aristotle and St. Thomas .
Philosophia perennis
V.

•
.
•
■
•

•

PHILOSOPHY AND THE SPECIAL SCIENCES .

102
103
107
108
108
.

Philosophy judges the special sciences . 111
It governs them
.
.
.
.113
It defends them
.
.
.
.117
It is pre-eminently free
.
.
.118
Further observations .
.
.
.118
Conclusion II
.123
12

PAGE
64

Ill

CONTENTS

PACE
VII.

PHILOSOPHY AND THEOLOGY

.

.

.

124

Nature of theology .
.
.
.124
Theology judges philosophy
.
.126
Philosophy submits to theology its
conclusions, not its premises . 126
Philosophia ancilla theologiae .
.
.129
Further considerations
.
.
.129
Conclusion III .
.132
VIII.

PHILOSOPHY AND COMMON SENSE

.

133

.

Unscientific knowledge
.
.
133
Philosophy is derived from common
sense, understood as the natural
apprehension of first principles . 136
Common sense may accidentally judge
philosophy . .
.
.
.138
Conclusion IV .
. 141
The method of philosophy
.
. 141

PART TWO
THE CLASSIFICATION OF PHILOSOPHY
I.

THE MAIN DIVISIONS OF PHILOSOPHY

.

.

Logic. Theoretical philosophy. Prac­
tical philosophy .
.
.
147
Their objects .
.
.
.
-151
Conclusion V
153
II.

logic

.

.

.

.

.

Correct reasoning .
.
.
Ideas and images
.
.
.
Conclusion VI .
Individual and universal .
.
Conclusion VII
IS

-154

154
.154
.156
157
. 159

147

CONTENTS
FACE

The problem of universals :
.
.159
(a) Nominalism .
.
.
159
(¿) Realism ..... 160
(c) Moderate Realism .
.
.160

III.

THE

PHILOSOPHY OF MATHEMATICS
PHILOSOPHY OF NATURE
.

The term body .
.
.
The philosophy of mathematics
The philosophy of nature .
(a) Mechanism
.
.
(Z>) Dynamism
.
.
(c) Hylomorphism
.
Psychology
.
.
.
Problem of the origin of ideas

AND
.

THE

.

172

.
.163
.163
.164
-165
.166
.166
-169
.170

.
.
.
.
.

.
.

.

Conclusion VIII

163

Abstraction: Problem of human nature 172
Conflicting schools .
.
.
. 174

IV.

CRITICISM (EPISTEMOLOGY)

Being qua being.
Criticism .
.
Problem of truth

.

.

.

.
.

.

.

.
.

.
.

.
.178
.178
.178
• 179

Conclusion IX .

Conflicting schools : .
.
.
(а) Scepticism
.
.
.
(б) Rationalism .
.
.
(c) Moderate intellectualism .
Problem of the object of the intellect
intelligibility

..

Conclusion XI .
H

181

.181
.182
.182
.183
. 185

.187

Conclusion X

Being and

.

.187
.

187

CONTENTS
FAGE

V.

ONTOLOGY : ESSENCE....................................................... 189

Problems of ontology.
.
Essence .
.
.
.
(a) In the wide sense .
(¿) In the strict sense .
Characteristics of this essence

.
.

.
.
.

Conclusion XII .

-189
-191
-191
.194
.197

.

201

Further observations .
.
.
.201
Our intellect can apprehend essence . 203

Conclusion XIII

203

.

Further observations ....
Essence is universal in the mind .
.
Conclusion XIV

.

203
205
207

Individual nature and matter :
.
207
(a) Individual nature .
.
. 208
(Z>) First matter .... 209
(c) Archetypal being .
.
.210
(d) Nature, essence, and quiddity . 213

VI.

ONTOLOGY :

.
.217
.222

SUBSTANCE AND ACCIDENT .

Origin of these notions
Substance
.
.

.
.

.
.

Conclusion XV

Further observations
Accident .
.
.

.
.

.
.
.

Conclusion XVI

224

.224
.227
.

227

Further observations .
.
.
.228
Conflicting schools .... 230
The individuality of substance .
. 233
(a) Substantia prima, substantia secunda 233
(¿) Per se, a se, in se
..
. 236
x5

217

C ONTENTS
PAGE

VII.

ONTOLOGY :

ACT AND POTENTIALITY

Origin of these notions
(a) Identity and change .
(Z>) Their apparent incompatibility .
(c) Solved by the concept potentiality
Potency or potentiality
Act .......
Conclusion XVII
The nature of change
Act and potentiality in things
Axioms i-vii .....
Conflicting schools ....
Terminology : .
(a) Material and formal
(¿) Virtual and formal (actual)
(c) Implicit and explicit
(d) In express act, in accomplished
act
....
VIII.

THEODICY (NATURAL THEOLOGY)

Subsistent being itself
IX.

THE PHILOSOPHY OF ART.

ETHICS

Introduction .....
The philosophy of art
Ethics
......
Divisions of ethics ....
Conflicting schools ....
CONCLUSION

......

Classification of philosophy

16

•
239
239
241
242
242
244
245
246
246
248
250
251
252
254
255

239

255
•
257

257

.
261
261
264
267
268

261

.
271

271

INTRODUCTORY
Philosophers were once called wise men. It was
Pythagoras who first invented the term philosophy
(cptXia
<rocptá£, love of wisdom),1 observing that
wisdom belongs in the strict sense to God alone, and
for that reason not wishing to be called a wise man,
but simply a friend or lover of wisdom. His modesty
was itself a mark of great wisdom, for the sublimity
and difficulty of the highest truths, and the weakness
of our nature “ in so many respects enslaved,” forbid
man to acquire “ a property right in wisdom ”1
2
such that he can employ it in entire freedom. As a
result of the many necessities to which he is subject,
he holds it only by an insecure title, so that he may
be termed not wise, but far more truly a beggar at
wisdom’s door. Nevertheless philosophy is nothing
other than wisdom itself so far as it is accessible to
human nature.
It is not a wisdom supernaturally infused into our
souls which man possesses in virtue of a superhuman
illumination. Neither is it a wisdom wholly sponta­
neous and unconscious (such as within its limits is
the prudence of animals, and even the wisdom of
simple souls), which he possesses in virtue of a natural
instinct. It is the wisdom of man as man, which he
1 Cicero, Tuse., v. 8 ; cf. Diogenes Laertius, i, 12.
2 Aristotle, Metaph. i, 2, 982 b. St. Thomas, In I Metaph., 1. 3.
De Veritate, q., 7, a. 7.
B

17

Cf.

AN

INTRODUCTION

TO

PHILOSOPHY

acquires by the labour of his intellect, and it is for
that very reason that his wisdom is gained with
such difficulty and held so insecurely, and that those
who seek it should be called philosophers rather than
wise men.
Such is the nature of philosophy derived from the
etymology of the term and its employment in ordinary
speech. A philosopher is a man humanly wise.
And the man who devotes himself to philosophy, by
so doing undertakes to show his fellows the sublimest
views at which man’s understanding can arrive of
the great problems which solicit the mind of the race.
The definition of philosophy as “ human wisdom ”
is still a superficial definition, and a nominal definition,
which simply renders agreement possible as to the
sense of the term. To attain a more profound defini­
tion, a real definition which reveals the nature of the
object, we shall study in the sequence of concrete
history the formation or genesis of what men have
agreed to call philosophy.
In so doing we shall follow, so far as it is possible
in an explanatory text-book, the actual method of
Aristotle, too often neglected by books which teach
his conclusions, but apparently ignore his spirit.
That great realist advanced nothing a priori and always
studied the historical development of a problem before
he proposed his own solution, which thus appeared
as the natural goal of a process of discovery. Such a
method will no doubt compel us to undertake a
considerable digression into the field of history, but
it is, nevertheless, in our opinion indispensable.
On the one hand, from the practical and educational
standpoint, an account of the historical origins of
18

INTRODUCTORY

philosophic thought is the best method of acquainting
beginners with the problems of philosophy, introducing
them into the world, entirely new to them, of rational
speculation, and furnishing them, incidentally, with
much extremely useful knowledge. Their first requisite
is to know what they are studying, and to possess a
sufficiently live and accurate notion of the problems
of philosophy presented in their simplest form.
On the other hand, in justice to our subject itself,
to state straight away, with no previous examination
or concrete justification, conclusions relating to the
nature of philosophy, its object, dignity, and so forth,
would be to present the traditional conception of
philosophy under an arbitrary and a priori aspect
wholly alien to it, and to risk enslaving our pupils to
empty formulae. By beginning, on the contrary, with
a brief outline of the history of ancient philosophy up
to Aristotle, that is to say until the conclusion of its
formative period, we display philosophy in its origin
and construction, and thereby show how the transition
was effected between the teaching of common sense
and the scientific knowledge of philosophers, how the
great philosophic problems arose of themselves, and
how a particular conception of philosophy, which will
be put later to the test of discussion, results inevitably
from this historical inquiry, and naturally forces itself
upon the mind. We need not fear to insist upon these
preliminary questions, which we shall have to consider
again from another angle in criticism. They concern
the very existence, the nature, and the value of
philosophy.

PART ONE
THE NATURE OF PHILOSOPHY

I
PHILOSOPHIC THOUGHT BEFORE PHILOSOPHY IN

THE STRICT SENSE

Philosophic speculation, precisely because it is
the supreme achievement of reason, is unknown to all
the so-called primitive races. Indeed, even of the
civilisations of antiquity the greater part either have
possessed no philosophy or have failed to discover
its true nature and distinctive character. In any
case, philosophy only began to exist at a very
late period about the eighth and especially the sixth
century b.c., and then found the right path to truth
by a success which must be regarded as extra­
ordinary when we consider the multitude of wrong
roads taken by so many philosophers and philo­
sophic schools.
Nevertheless, some of the most elementary truths
with which philosophy deals were known long before
philosophy itself had come to birth, and the more
important of these are to be found in a more or less
rudimentary form and more or less seriously cor­
rupted among all the peoples of antiquity, even at
the most remote epochs. But it was not from the
philosophers that these peoples had learned them ;
their knowledge was derived in part from that wholly
spontaneous and instinctive exercise of reason which
we call common sense, but above all from primitive
tradition.

23

AN

INTRODUCTION

TO

PHILOSOPHY

The most reliable inductions of history combine with
the conclusions of theology1 to prove the existence of
a primitive tradition, common to the different branches
of the human race and going back to the origin of
mankind. And even in default of any positive sources
of information, it is a very reasonable conjecture that
the first man received from God knowledge together
with existence, that by education he might complete
the work of procreation.
But was it possible that this knowledge, together
with the primitive religion in which it was incorporated,
could be transmitted in its integrity by the human
race ? We have, on the one hand, truths of the
loftiest sublimity to be handed down from one
generation to another, yet, on the other, an intelligence
dominated by the senses and imagination. A dis­
proportion so extreme inevitably deteriorated the
tradition received at the outset, as little by little the
rust of oblivion gathered upon it, error defiled it,
and it fell a prey to the corruptions of polytheism and
the more degraded forms of religion (animism,
totemism, idolatry, magic, etc.). Nevertheless, in
spite of the changes which it underwent, the primitive
tradition has preserved for mankind throughout the
ages a deposit, progressively diminishing no doubt, of
fundamental truths. In this deposit were included
many philosophic conceptions—that is to say, concep­
tions which concerned the most sublime problems
within the scope of reason. But since they were
taught only by a religious tradition which corroborated
the instinctive teachings of common sense, they were
1 P. Lemonnyer, O.P. (following Schmidt), La Révélation primitive
et les données actuelles de la science. Paris, 1914.

24

PRE-PHILOSOPHIC

THOUGHT

known in a pre-philosophic fashion and existed in a
pre-philosophic state.

It is not surprising that all peoples in the primitive1
stage of history were ignorant of philosophic speculation.
But it is more astonishing that even certain civilisations
were devoid of philosophy—for example, the Semitic,
and the Egyptian, which is, in this respect, in the same
category as the Semitic. Despite the high level of
scientific culture reached by the intellectual aristocracy
of these races, the sole philosophic conceptions, it would
seem, which the Egyptians and Chaldeans possessed
were a few very general ideas, implicit in their religion,
concerning the Deity, the human soul and its state
after death, and the precepts of morality. These
truths, which, moreover (as in the case of every race),
are purer the further back we follow their history, were
never made the subject of rational study and specula­
tion, but were simply accepted, as also were their
scientific beliefs, as part of a sacred tradition.
Religion took the place of philosophy, and from
religion these races received certain philosophic truths ;
philosophy they had none. In this matter the Jews
did not differ from their fellow Semites. Scornful
of human wisdom and the achievements of pure
reason, and, indeed, without aptitude for such
investigations, they produced no philosophers (at
least not before Philo, who was a contemporary of
1 Primitive in respect of a particular branch of the great human
tree and so far as our knowledge of the past extends, but not primitive
in the absolute sense. Far behind what we term the primitive state
of the peoples known to us lies a long stretch of human history of which
we know nothing.

25

AN

INTRODUCTION

TO

PHILOSOPHY

Jesus Christ), but they possessed the prophets and the
Law.
All the great Indo-European civilisations, on the other
hand, manifest an impulse, which no doubt took
widely different forms, towards rational and, in the
strict sense, philosophic speculation. But, except in
Greece (and to a very partial extent in India), this
impulse nowhere succeeded in achieving an indepen­
dent scientific discipline distinct from religion. A
traditional religion did not in this case take the place
of philosophy, but philosophy, or, we should rather
say, human wisdom, penetrated religion and was
confused with it. The wise man fulfilled a sacred
function. He was not the head of a philosophic
school, but the founder of a religious sect, if not of a
new religion.

(a) Among the Persians,1 whose original religion, so
far as we know it from inscriptions, was a fairly pure
monotheism, Zoroaster or Zarathustra founded Mazdeism
or Zoroastrianism (about the eighth or sixth century
B.c. ?), a powerful achievement of speculation which
systematised (and incidentally distorted) certain funda­
mental truths derived from the primitive tradition,
1 In this summary review of the great Aryan religions, we have been
obliged not only to isolate by a process of abstraction the intellectual
aspects of those religions with which the philosopher is concerned,
but, moreover, to simplify considerably and reduce to an artificial
classification doctrines whose vast and fluctuating complexity (this
is especially true of Brahmanism and Buddhism), and occasional
inconsistency, dismay historians. It should be added that the explana­
tions of Oriental thought given by scholars are still largely conjectural
and, in all probability, especially as far as philosophy is concerned,
in many cases extremely inadequate.

26

P R E - P HI L O S O P HI C

THOUGHT

in the attempt to give a rational explanation of the
vast problem which has faced human thought from
the outset, the problem of evil. By his failure to
perceive that God is the sole supreme principle and
the source of everything which exists, so far as it
partakes of being, and that evil is mere privation of
being without positive existence, and therefore that
no creature is evil by nature, Zoroaster ended in
dualism and taught the existence of two principles
uncreated and co-eternal, the principle of Good
(Ormuzd) and the principle of Evil (Ahriman), who
share the dominion of the universe and whose un­
relenting struggle constitutes its history. So far as
Ahriman is to be identified with the rebel angel of
primitive tradition, Zoroastrianism tended to make
the devil a god striving against God.

(b) Among the peoples of India, whose intellectual
and religious history is far more complex (since in
this field no certainty has yet been reached, we
present the interpretation of their beliefs which seems
to us most probable), we witness a remarkable pheno­
menon. When the original religion—the primitive
refigion of the Vedas1—no longer proved sufficient to
satisfy the intellectual demands or social needs of a
more advanced civilisation, philosophic notions, which
seem to have originated as interpretations of sacrifice
and other sacred ritual, but developed in a spirit
hostile to the ancient traditions and the cult of the
1 The most ancient among the religious books of the Hindus {Veda
means knowledge), the Rig-Veda, is apparently not older than the
twelfth century B.a. Vedic religion seems to have been an incoherent
polytheism coloured by a vague pantheism.

27

AN

INTRODUCTION

TO

PHILOSOPHY

gods, found a home among the sacerdotal caste and
took possession of the priesthood. To reconcile the
perpetuation of their office with their new opinions,
the priests, while continuing to perform the traditional
ceremonies, directed their worship no longer to the old
gods, but to the undefined and secret forces of the
universe.
(i) This resulted, after a period of confusion, in
the formation of a new system, Brahmanism (or Hindu­
ism), which is essentially a philosophy, a metaphysic,
a work of human speculation, but being, so to speak,
clothed in the ornaments of the sanctuary, was invested
from the outset with the sanctions and attributes of a
religion. A divine origin was ascribed to the books
in which it was taught (the Brahmanas and Upanishads'),
and they could be obtained only from the priests.
Hence Brahmanism may be called a sacred, hieratic
or theological metaphysic, and already in the eighth
century b.c. the supremacy of the priestly caste among
the Hindus seems to have realised in its fashion that
social and spiritual sovereignty of the philosopher­
priest and the religion of science which was the dream
of certain nineteenth-century thinkers.
It is true that the science which those thinkers wished
to invest with a sacred character was the science of
phenomena, or, as it was termed, positive science, which
is not wisdom, even human, and, as Auguste Comte
justly observed, is incapable of producing order in
any department. The human science to which
Brahmanism gave a divine character was, on the
contrary, the science of ultimate realities, metaphysics,
human wisdom in the strict sense : a powerful effort
of metaphysical thought (so far as we can judge of it
28

PRE-PHILOSOPHIC

THOUGHT

from documents whose interpretation is still far from
certain), but the product of reason still untrained,
incapable of making the necessary distinctions and of
avoiding internal contradictions, seduced by the
dream of an intuitive knowledge of the All, angelic
rather than human, and doomed by its very ambition.
This system, at least when we consider its pre­
dominant tendencies, taught that the First Principle
of the world, named Brahma 1 or Atman* constitutes
in himself the intimate reality of everything which
truly exists, whence logically follows pantheism, or the
identification of God with his creation.3 Nevertheless,
1 From the name of the occult and sacred force which gave ritual
its efficacy and pervaded all things. Originally regarded as the first
emanation of the supreme God, it became for the Brahmans the
unique source of being. The masculine noun, Brahma, designates
the First Principle as God and Lord, the neuter, Brahman, as the one
impersonal substance.
2 From the name of the principle of life (the “ self” transcending
the phenomenal individual), which was regarded as animating man
and the universe.
a The term pantheism is relatively recent, having been introduced
into the vocabulary of philosophy by Toland in the eighteenth century.
But the doctrine it designates is as ancient as the earliest philosophical
errors.
For a system to be pantheistic, it need not explicitly identify God
and creatures (very few pantheists fulfil this condition). It is sufficient
that its teachings are logically irreconcilable with an absolute distinction
between God and creatures.
This observation is particularly important for the study of Oriental
philosophies, of which pantheism is the original sin. Indeed, it arises
in their case from the very method of thought they employ, which
appears to consist primarily in the treatment of analogous concepts
(realised differently in different objects) as though they existed as
such outside the mind, which led them to conclude that things which re­
main the same become on different planes of reality essentially different.
For example, Atman is both the supreme principle of the universe,
transcending all multiplicity, and the principle which distinguishes
and constitutes every personality. Like the Schoolmen, but for

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an attempt was made to avoid this conclusion. The
Supreme Principle, which possesses neither personality
nor knowledge, to which no attribute can be applied,
which is absolutely unknowable by any concept,
however universal, not even by the concept of being,
so that it must be called Nothing or Non-Being, is
the sole true reality. Therefore the existence of
everything multiple or limited, everything we can
know by our senses or even by our concepts, is as
such illusion, mere appearance. This is idealism, the
denial of the reality of the world and of things. But
the bare existence of this appearance or illusion is an
evil, indeed evil pure and simple. The existence of
individual objects and of this cosmic delusion which
is called Nature (Maya), and which keeps us captives
of the manifold and the transitory, is essentially evil
and the source of all suffering.
The problem of evil, therefore, seems to dominate
the entire speculation of the Indian metaphysicians,
as also of the Persian sages. But the Persians, whose
bent was practical, always considered evil under the
aspect of sin, and, obsessed with the differences between
moral good and evil, which they attempted to use
as a criterion to divide beings into two metaphysical
categories, ended in dualism. The Hindus, on the
different reasons, the Indians distinguish between the personality
(which is for us the spiritual subsistence of the soul) and the material
individuality (which arises from the dispositions of the body).
This mode of thought, which we meet again more or less emphasized
in every doctrine of theosophic orientation, makes it possible to avoid
the appearance of pantheism, because its inherent self-contradiction
permits the affirmation of essential differences between terms which
should logically be identified. But, precisely because these affirmations
are only possible in virtue of a fundamental self-contradiction, it
inevitably involves a real pantheism.
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contrary, exclusively occupied with contemplation,
regarded evil pre-eminently under the aspect of
suffering, or rather privation, in the sense in which
metaphysicians understand the term.1 Led astray
by a profound realisation of a great truth which they
were unable to apprehend clearly (for while it is
very true that it were better for us not to exist than
to exist without being united to God, they believed
it were better for all things not to exist than to exist
without being God), they ended in a pessimism
which, though undoubtedly very different from the
romantic pessimism of a Schopenhauer, was primarily
the barren renunciation of a proud intellect, and
attempted to be self-sufficient.
What, then, in their conception did wisdom teach
man ? It taught him to free himself from suffering
and illusion, and with that object to rid himself of all
individual existence. The Brahmans held the doctrine
of the transmigration of souls, or metempsychosis ; they
believed that souls, on the death of the organism which
1 From this point of view Indian speculation may be said to afford
a prominent example of pure metaphysical intellectualism. Regarding
things solely from the standpoint of intellectual speculation and the
universal order, and not from the standpoint of the rectitude of the
human will and that particular order by which man is ordered to his
last end, it quickly came to lose sight almost entirely of the notion of
moral good and evil, and its ethics consists primarily in a metaphysical
purification, directed exclusively to a particular ideal of intellectual
knowledge.
An analogous tendency is observable in every system which confuses
by an exaggerated intellectualism the moral with the metaphysical
order (a confusion which is glaring in Spinoza’s Ethics, for example)
and, failing to recognise that God is not only the provisor universalis
of creation, but also the provisor particularis of the moral life (cf. St.
Thomas, Sum. Theol. i, q. 103, a. 8, with Cajetan’s Commentary), ends by
claiming to transcend the distinction of good and evil and denying
the existence of moral evil.

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they had animated, passed into another organism,
thus living successively in different bodies of men,
animals, or plants.1 The punishment of the wicked
and foolish consisted accordingly in continuing to
undergo in a series of reincarnations the pain of
individual existence. The soul of the wise man, on
the contrary, was delivered from the yoke of transmi­
gration ; absorbed or reabsorbed in Atman, it escaped
the sufferings of the world by losing all distinctive
individuality.
The ethics of Brahmanism teaches the means
whereby this deliverance can be achieved ; the
wise man progresses towards that goal in this life by
means of contemplation. Brahmanism understands
that contemplation is a beginning of beatitude in
this life ; but, as it mistakes the nature of beatitude, so
it mistakes the nature of contemplation. The con­
templation which it claims to teach is, in fact, only
a metaphysical contemplation, or rather a species of
supra-rational vision, which it expects to achieve by
the merely natural powers of the created intellect ;
unlike Christian contemplation, it is the product of
the intellect alone, not of supernatural charity and the
1 So, at least, metempsychosis is currently understood. It is not
unlikely that this interpretation of the doctrine is the popular translation
of a doctrine less crude, according to which every being passes through
an indefinite series of states or cycles of existence, each of which is only
lived once, and our earthly existence is simply one particular state
among many others. If this be the case, the doctrine of successive
reincarnations originated in an unintelligent distortion of this theory,
still further corrupted when it was introduced into the West. (The
possibility, however, remains that originally the Pythagoreans and
Orphies understood the transmigration of souls in a symbolic sense.)
It is also possible, on the contrary, that the theory in question was
a learned interpretation, elaborated by the Indian metaphysicians, of
a popular belief in transmigration.

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infused wisdom which accompanies it. Its aim is
union with God by knowledge, not by love. Instead
of admitting an activity overflowing from its own
superabundance, it withdraws from activity of any
kind, which it abandons wholly to the inferior powers.
By this metaphysical contemplation, Brahmanism
proposes to put us gradually in possession of our last
end and initiate us into the blessed state of the
delivered. Since it thus strives to reach by man’s
unaided powers heights which grace alone can attain,
it results in a pseudo-mysticism of a purely intellectual
character (in contrast to other, purely emotional, forms
of false mysticism) in which the wise man, hoping
not only to be united with God, but to blend with him,
intoxicates himself not with God, but with his own self­
annihilation. Hence (apart from those instances of
genuine spirituality which grace is always free to
produce) a host of counterfeits of supernatural
mysticism, also of ascetic exercises and methods,
including among their baser forms (with the fakirs)
those tours de force of exaggerated asceticism which
prove that the mortification of the flesh, when not
regulated by reason and dictated by love, can be as
fallacious as pleasure. Naturalism is thus the final
characteristic and the capital vice of Brahmanism,1 as
indeed of philosophic mysticism in general, whether
it be the product of Brahmanism, Buddhism, neo­
Platonism, or Islam.
(ii) From the sixth century onwards new schools
1 We do not mean that Brahmanism descends to the adoration of
sensible nature, above which,’on the contrary it claims to rise completely.
By the term “ naturalism ” we here mean the claim to arrive at union
with God and perfection without the supernatural assistance of grace.
G

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arose in India, some orthodox, others heterodox. Of
these the principal was that founded by Çakya-Muni,
surnamed the Buddha 1 (the enlightened, the sage).
Buddhism, a doctrine essentially negative and solvent,
directed, moreover, to practice rather than to specu­
lation, may be regarded as the corruption and dis­
solution of the Brahman philosophy.
Substituting for that which is that which passes away,
refusing to say that anything does or does not exist,
and admitting only a succession of impermanent
forms without fixed foundation or absolute principle­
in other words subordinating being to what is known
as becoming or fieri—it showed, at the very time at
which in Greece Heraclitus formulated the philosophy
of flux, all the characteristics of a perfect evolutionary
system, and, if it declared the existence of God, as
of a substantial self and an immortal soul, unknow­
able (agnosticism), its real tendency was to deny the
existence of God (atheism), and to substitute for
substance of any kind a stream or flux, regarded
indeed1
2 as itself real, of forms or phenomena
(phenomenalism).3 Hence for Buddhism metempsy­
chosis consists in a continuous chain of thoughts and
feelings (a stream of consciousness, as we should term
it to-day) passing from one mode of existence to
another in virtue of a sort of urge towards life, due
itself to the desire to live : it is desire which is the
1 His actual name was Gautama. The name Gakya-Muni means
the ascetic or hermit (muni) of the race or clan of the Çakya. Buddha
lived during the second half of the sixth century B.c. ’ He would seem
to have died about the year 477.
2 At least by Buddha’s original disciples.
3 “ Everything is empty, everything unsubstantial ” was a saying
of Buddha’s.

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cause of existence and “ we are what we have
thought.”
At the same time, the teaching of deliverance from
suffering, which in Buddhism, even more than in
Brahmanism, dominates the entire system, assumes a
different and even more radical form. Evil is no
longer merely the possession of individual or personal
existence ; it is existence itself : it is evil to be, and the
desire of existence is the root of all suffering. The
wise man must therefore destroy in himself man’s
natural longing for existence and for beatitude, the
fullness of being ; he must abandon all hope and
extinguish every desire. He will thus attain the state
of emptiness or total indetermination called nirvana
(literally nakedness, metaphorically immortality, refresh­
ment, the farther bank—the term, in itself indefinite, was
never defined by Buddha), which will deliver him
from the evil of existence and the yoke of trans­
migration, and which, in the logical consequence of
Buddhist principles, must be regarded as the annihila­
tion of the soul itself. For since the soul is only the
chain or current of thoughts and feelings which derive
their existence from the desire to be, to extinguish that
desire is to extinguish the soul.
This nirvana is the goal for whose attainment
Buddhism made use of the ascetic practices which it
took over with considerable mitigation from Brahman­
ism, also of its moral code 1 which is thus directed,
not to God, but to a species of mystical nothingness
1 We here understand moral code in a very wide sense as meaning
a code of behaviour. If the expression be taken as implying moral
obligation, whose ultimate basis is the Christian doctrine of God
the transcendent Creator, we must conclude that Buddhism, as indeed
all the Oriental religions, Indian or Chinese, has no moral code.

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as its last end. Moreover, the source and ultimate
measure of Buddhist ethics is man, not God. If it
rejected the system of castes which exaggerated
the demands of social order and divided man almost
into distinct species, it was only to dissolve social
order of any kind in an absolute equality and
individualism. And though it prescribed a universal
benevolence (which extended even to prohibiting
the slaughter of animals and to a compulsory
vegetarianism), almsgiving, pardon of injuries, and
non-resistance to the wicked, its motive was not love
of one’s neighbour as such, whose positive good and
(by implication) existence we are bound to will, but
to escape suffering to oneself by extinguishing all
action and energy in a kind of humanitarian ecstasy.
Buddhism is, therefore, a proof that gentleness and pity,
when they are not regulated by reason and dictated
by love, can deform human nature as much as
violence, since they are then manifestations of
cowardice, not of charity.
This doctrine of despair is not only a heresy from
the point of view of Brahmanism ; it is an intellectual
plague to humanity, because it proceeds from the
negation of reason. It is not, therefore, surprising
that we find in it the majority of the fundamental
errors by which contemporary attacks on reason are
inspired. If at the present day it has found a warm
welcome among certain circles in Europe, it is because
all those who hope to derive from humanitarianism a
moral code of human kindness for the acceptance of an
atheistic society are already implicitly Buddhists.
(iii) Buddhism is a philosophy, agnostic and
atheistic, which nevertheless usurps the social and
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ritual functions of a religion. It is as a religion that
it has won the allegiance of so many millions? In
certain other schools to which Brahmanism gave
birth—schools recognised as “ orthodox ”—we find,
on the other hand, a tendency towards the normal
distinction between philosophy and religion.
These darshanas, it is true, would seem to be not so
much distinct systems as complementary aspects of
one and the same doctrine, the Brahmanist meta­
physics. Here we may pass over the Vedanta, the
most complete statement of that metaphysics and its
doctrine of deliverance ; the Mimamsa, a species of
commentary on the ritual and an explanation of the
unseen forces set in motion by every act ; the Sankhya,
founded, it is said, by Kapila (fifth or sixth century
B.c. ?), which treats of the emanation of all things from
their source, and seems to have taught, like Plato, a
psychological dualism which explains suffering by
the union souls contract with matter ; and also Yoga,
which teaches the practical methods which lead to
contemplation, that is to say, the total loss of conscious­
ness and identification with the universal Being
(Ishvard) by a supra-rational knowledge. But the
darshana Vaisesika, ascribed to Kanada (about the fourth
century b.c. ?), which includes a rough outline of
cosmology, and divides everything which exists into a
number of fundamental classes or categories, sub­
stance, quality, movement, association, difference, and
1 However, in proportion as it has secured wide acceptance, Buddhism
has ceased to be atheistic, only to fall into the most degraded concep­
tions of deity. Popular Buddhism as practised to-day in many parts
of Asia, where, to adapt itself to existing beliefs, it has assumed the
most varied shapes, is nothing more than a form of idolatry, totally
different from philosophic Buddhism.

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inherence, and explains the four elements of ponder­
able matter, earth, water, air, and fire, by the union
of indivisible and indestructible particles, “ atoms ” in
the language of philosophy,1 and the darshana Nyaya,
founded by Gotama, which attempts to construct a
theory of reasoning and proof—that is to say a logic,
though a logic extremely confused and incomplete—
are clearly the rough sketches of a work strictly and
solely philosophical. But these crude attempts did
not lead to a completed system, and Indian thought
never achieved a rational and autonomous philosophy.

(c) When we turn to the Far East and consider the
very ancient civilisation of China,1 we find that when
the primitive religion of the Chinese, which seems to
havebeen fairly pure,123 had from the twelfth century b.c.
undergone gross corruption and materialisation,
substituting the sky for God,4 worshipping the sun and
moon, paying divine worship to the souls of ancestors
and to spirits, and allowing itself to become tainted
by magic and sorcery, wise men were compelled here
1 Ranada, however, to explain this union, attributed real qualities
to his atoms. Observe that Brahmanism, which rejects atomism,
admits five elements (ether being the fifth) ; Buddhism on the contrary,
which has welcomed atomism, only four.
2 Whatever be the racial appurtenance of the Chinese, their history
undoubtedly shows closer connections with the Aryans than with the
Semites. It is for this reason that Chinese philosophy is discussed
in the present section.
3 It taught the existence of one sole God—Shang-ti—personal,
intelligent, distinct from the world, Sovereign Ruler of the races of
mankind ; also the immateriality and immortality of the human soul,
and even offered to the spirits of ancestors the same sacrifices and
marks of reverence as to the good spirits who are guardians of men.
4 In all probability Heaven (Tien) was in origin simply a meta­
phorical synonym of the Sovereign Ruler (Shang-ti).

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also to seek a remedy for a decadence which about
the sixth century b.g. threatened their civilisation with
utter ruin.
It has long been believed that the Chinese sages
were simply moralists wholly occupied with laying
down rules of conduct and completely indifferent to
metaphysical speculation. This is a true account
only of Confucius and his followers ; it does not seem
to be applicable to Lao-Tse, though we can only
accept with considerable reserve the interpretations
of his teaching offered by certain modern Taoists.
According to their account, Lao-Tse (born 604 b.g.)
was himself the disciple of a tradition whose oldest
monument is the Yi-King, a book which consists
essentially of sixty-four graphic symbols (hexagrams or
double trigrams) arranged in a series of mechanical
groups,1 formed by combining simpler signs and
susceptible of very many interpretations (metaphysical,
logical, mathematical, moral, political, astronomic), each
number corresponding analogically with the others.
The metaphysical speculation of the Yi-King appears
to have been primarily concerned with the question,
How can the Absolute, being wholly self-sufficient, act
and manifest itself? It distinguishes in the supreme
and sole First Principle or Perfection two different
aspects, Chien, the unmoving and unknowable source
of all activity, and Chuen, knowable activity, which
eternally manifests perfection in a process of spiral
evolution and an endless flux of forms. But these
two aspects merge in one single and self-identical
being, and all things, after passing through all the forms
1 Raymond Lull, in his attempts to create an ideographic algebra,
employed an analogous procedure.

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of evolution (of which the human cycle is but one
curve), must return to Chien. This metaphysic may
therefore be described as a species of evolutionary
pantheism. It constitutes the foundation of Lao-Tse’s
system (Taoism), his chief contribution being an
element of occultism and asceticism.1 Tao (the Way),
the eternal goal and process of evolution, is the road
by which all things must pass to arrive finally at the
complete cessation of activity {Nibban, the Chinese
nirvana}, in which they are reabsorbed in nothingness
and become one with the first principle of all activity.
The wise man will imitate the Tao by cutting himself
off from all things, for the Way, though it has pro­
duced beings, does not partake of their movements.
“ Having built this house, it dwelleth not therein.”
Detached from wealth, passions, and sensible experi­
ence, and knowing that evil is mere appearance, he
trains himself in solitude, secrecy, and humility (a
humility which has nothing in common with the
Christian virtue of that name, being nothing more
than prudence and contempt for one’s fellow men),
until he reaches a state of perfect knowledge in which
he no longer acts except by the pure intelligence.
The wisdom, the illusory wisdom, to which Taoist
asceticism leads its disciples, an asceticism which
makes use of opium, as Buddhist asceticism of hypnosis,
is for man a principle of revolt, therefore the adept
1 It may be added that in the twelfth century a.d. Chu-Hi, who
has been regarded, mistakenly it would seem, as a materialist,
formulated, in the tradition of Lao-Tse, a system which in the Chinese
system of education has become, practically speaking, the official
philosophy. It explains the constitution of things by a dual principle
(ZZ and ki) which is not without resemblance to the duality of form
and matter in Aristotle and the Alexandrians.

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must keep it a secret for himself and a narrow circle
of initiates.1
No doubt Confucius (Kung-fu-tse, 551-479 b.c.),
who, unlike Lao-Tse, represents for the Chinese a
moderate and practical wisdom (which, from its place
in their system of education and its own active
character, is generally accessible), preserved many
truths of the primitive wisdom. He avoided, however,
every ultimate question, and confined himself to an
ethic purely human, social, earthly, and even
commonplace. Opportunism, he observes, is the
distinctive mark of the wise man. Every predeter­
mined line of action, every preconception is a mistake.
In all matters one should pursue a middle course,
live unfettered by one fixed purpose, embrace no
opinion with enthusiasm, reject nothing because it is
antipathetic, do whatever seems best in the circum­
stances of the moment and as the situation demands.
Confucianism, a system intended for the multitude,
ended in pure materialism. Taoism, which claimed
to address a small circle, and which, if the interpreta­
tion given above be correct, constitutes, together with
Brahmanism, one of the most singular attempts ever
made by man to attain, in that ignorance of love
which seems an aboriginal characteristic of Oriental
thought, a wisdom exclusively of the intellect, by
which he could deify himself in metaphysics, has
experienced in China alternate periods of triumph
and persecution, and has organised, apparently ever
since the opening centuries of our era, secret societies
1 “ Empty their heads, and fill their bellies,” was Lao-Tse’s advice
to a statesman ; “ weaken their minds and strengthen their sinews.
To teach the people is to ruin the State.”

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in which it has definitively taken refuge since the
seventeenth century and in which it has degenerated
into a philosophic and political occultism of the most
pernicious type.
This brief historical sketch has shown the important
part in the life of humanity played by sages and their
wisdom. All these nations, situated on the frontiers
of darkness, and lacking a divine revelation of truth,
were obliged, when their religions proved incapable
of satisfying the needs of the individual soul or of
society, to have recourse to the wisdom supplied by
human reason. This wisdom, in the civilisations of
which we have spoken hitherto, was never differentiated
from religion, but, on the contrary, encroached on
the domain of the latter and claimed to conduct men
to their last end, until in India we actually find that
Brahmanism successfully achieved that canonisation
of metaphysics which threatened the Greco-Roman
world in the reign of the neo-Platonic emperor,
Julian the Apostate. It achieved also that transfusion
into religion of a human philosophy attempted by
Kantian metaphysics in the nineteenth century
{Modernism').
It has also shown how this human wisdom has
everywhere proved bankrupt, and how, even before
philosophy took shape as an independent discipline,
most of the great philosophic errors had been already
formulated. From the very first, the most arduous
problems tower like mountains before the intellect
of man ; the problem of evil, the problem of being,
the problem of the becoming and flux of things.
It is not, therefore, surprising that a reason liable to
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THOUGHT

error the moment it transcended the elementary
truths within the range of common sense, a reason
still unstable and undisciplined, and therefore all the
more ambitious, went astray from the outset and
opened the history of metaphysics with the dualism
of Zoroaster and the pessimism of the Hindu, the
pantheism and idealism of the Brahmans, the atheistic
evolutionism of Buddha, and the illusory wisdom of
Lao-Tse. When it became more modest, it was only
to fall into the ethical positivism of Confucius, re­
nouncing all sublimity and even denying its own
raison d'etre. Nor should it surprise us to find the
same errors reappearing at a later stage, when philo­
sophy had been fully elaborated. Error, at whatever
period of human history it may arise, is due to a failure
of man’s reasoning power—is, so to speak, a return of
its primitive weakness, and therefore of its very nature
retrograde.
A further fact, however, calls for remark here, a
fact only too well established by this prehistory, so
to term it, of philosophy : namely, that these funda­
mental errors are not unsubstantial and insignificant
dangers ; they may succeed, to the bane of those
diseased cultures which they condemn to sterility.
Truth (in all matters which transcend the data of
common sense) is not, as those are apt to believe who
have had the good fortune to be born into a culture
formed by it, given to man ready made, like a natural
endowment. It is difficult to attain, and hard to
keep, and only by a fortunate exception is it possessed
uncontaminated by error and in the totality of its
various complementary aspects. We have therefore
the most urgent cause to be grateful for the possession
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of a revelation, by which God has given us from on
high, besides a knowledge of supernatural truth
inaccessible to reason, a sure and easy access to the
essential elements of the same truth which, so far as it
falls within the natural order, is indeed accessible to
our speculation, but can be so easily missed by it.
Those also have the strongest claim on our gratitude
who from below, by the strenuous exercise of their
reason and unaided by revelation, succeeded in
bringing to light the principles and laying the perma­
nent foundation of this natural truth, and in con­
structing a true and progressive human wisdom, in
other words a philosophy, which, when met later
and raised by the truth revealed from heaven, would
be incorporated into the fabric of a higher wisdom,
theology, the wisdom of man deified by grace, wisdom
in the highest sense of the term. How highly there­
fore ought we to prize the sacred heritage of Greek
thought !
In Greece, alone in the ancient world, the wisdom of
man found the right path, and as the result of a
fortunate harmony of the soul’s powers and of a long
effort to achieve mental order and discipline human
reason attained its full vigour and maturity. In con­
sequence, the small Hellenic race appears among the
great empires of the East like a man amidst gigantic
children, and may be truly termed the organ of the
reason and word of man as the Jewish people was the
organ of the revelation and word of God.
It was in Greece alone that philosophy achieved
her autonomy and was explicitly distinguished from
religion. At least during the purest and most glorious
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age of the Hellenic mind, it recognised its own
boundaries and was content to claim a strictly limited
territory—the scientific study of purely rational truths
—whereas Greek religion, already very much degraded
in the time of Homer, became increasingly incapable
of satisfying the needs of the intelligence, and grew
more corrupt every day. True, the time would come
when the Greeks, arrogantly abusing philosophy and
reason, would attempt to embrace the things of God
within the limits of their wisdom, “ would become
vain in their thoughts ” and deserve the condemnation
pronounced by St. Paul on the wisdom of this world,
“ which is foolishness in the sight of God.” But their
philosophy, though born of their mind, is undefiled
by their corruptions, and its sole object is the truth.

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II
the pre-socratig philosophers

I he earliest thinkers of Hellas were the poets, the
interpreters of traditional religion. Myth-makers, like
Hesiod or Homer, sometimes prophets, such as that
Epimenides of Cnossos who purified Athens from
pestilence by erecting altars to unnamed divinities,
they have no place in the history of philosophy in the
strict sense. Greek philosophy, as Aristotle shows,
only began with Thales of Miletus, one of the Sages
or Gnomics, who lived in the seventh or sixth cen­
turies B.G.1
The primary aim of these Sages, traditionally seven
in number (their names are variously handed down
by ancient writers), was to improve the conduct of
their fellow citizens. Their aphorisms, some of which
Plato quotes in the Protagoras, do no more than embody
the practical lessons they had learned from their
experience of life. They were men of action, legisla­
tors, or moralists, men of prudence, but not yet
philosophers. Alone among them Thales embarked
on scientific speculation. Geometrician and astrono­
mer, he demonstrated that all the angles inscribed in
a semicircle are right angles, and appears to have
predicted—no doubt owing to his acquaintance with
1 For the fragments from the early philosophers quoted in this
chapter Professor Burnet’s translation {Early Greek Philosophy) has been
used ; for Aristotle’s Metaphysics Professor W. D. Ross’s translation.

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Babylonian science—the total eclipse of the sun which
occurred on May 28th, 585.
The philosophers who succeeded him were still for
the most part men who played an active part in public
affairs, ardent politicians of the city state ; but, in
spite of this practical activity, they were more or less
clearly conscious from the beginning of the true nature
of their wisdom. Moreover, save in the case of a few
exceptional individuals (for instance, Empedocles,
the miracle worker, and Pythagoras, who founded a
religious sect), Greek philosophy was from the very first
distinct from refigion—indeed it took shape as a critic
and foe of the popular mythology and was manifestly
the product of pure reasoning.
In this work we are concerned only with the
progressive development of Greek philosophy from
Thales to Aristotle, for it was during this period that
philosophy, with its absolute validity for mankind as
a whole, took definite shape. The process occupied
some three centuries and is divisible into three great
epochs—the period of formation (the pre-Socratic
philosophers), the period of crisis (the Sophists and
Socrates), the period of fruitful maturity (Plato and
Aristotle).
THE IONIANS

(«) Human reason now set out with its unaided
powers in search of the principles and causes of things.
What first strikes man’s intelligence is what he sees
and touches, what he knows by his senses, and when he
attempts to understand anything, he begins by asking
what it is made of. Therefore the first thinkers of
Hellas only considered in things the material of which
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they are made, their matter (what we shall learn to
call the material cause), which they naively took to
be a complete explanation of the object. Moreover,
since the most universal and most important
phenomenon of nature is change, especially the change
by which one body becomes another (e.g. bread
becomes flesh, wood fire), they concluded that the
original matter of which all things are fashioned must
be identical in all, the common subject of all corporeal
changes. But since they were still unable to conceive
any impalpable or invisible principle, they thought
they had discovered this matter in some one of the
elements perceived by the senses.
Thales, for example (624-546), influenced by
traditional myths which derived all things from the
primordial waters, and arguing from the fact that
plants and animals “ are nourished by moisture ”
and that the germ of animal life is moist, concluded
that water is the sole substance, preserving its identity
through all the transformations of bodies. For
Anaximenes (588-524) this substance was air, for
Heraclitus (540-475 ?) fire, for Anaximander (610547) the boundless (by which he understood the
indeterminate, arcsipov), a fusion of all the contraries.
Moreover, water, air, fire, and the boundless were
regarded as something active, living, and animate,
endowed by an internal force with a manifold and
unlimited fecundity. This was the meaning of Thales’s
dictum, all things “ are full of gods,” rexv-ra tcXtjpt)
OsóSv.1 From the history of this extremely primitive
Ionian school, whose philosophy is termed hylozoist
because it ascribed life (Çwrç) to matter (ÛXtj), we learn
1 Aristotle, De Anima, i, 5, 411 a 7.

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to regard as the most elementary and crude of
philosophic doctrines the materialistic monism which
teaches the existence of a one single substance of a
material nature, and evolutionism, which attempts to
explain everything by an historic process of unfolding,
development, or evolution of something pre-existent.
Evolutionism, which, owing, on the one hand, to
German metaphysics, on the other to Darwin and
Spencer, became so popular in the nineteenth century,
was already taught in Greece by the physicists of
the sixth and fifth centuries b.c.1 Anaximander in
particular taught the eternal evolution of worlds
“ which rise and set at long intervals,” and held that
animals sprang from the mud of the sea floor, clothed
at first, as with a species of shell, in a prickly bark
which they shed on dry land,2 and that man arose from
animals of another species,3 having been originally
formed within the bodies of fishes, where he developed,
being ejected as soon as he had become sufficiently
large to provide for himself.4
Later Empedocles of Agrigentum (493-433 ?), whose
speculation in other respects marks an advance on that
of the lonians,5 explained the origin of living beings
1 In India about the same date Buddhism was formulating, as we
have seen, the religion of evolutionism.
2 Plac. Philos., v, 19, I. Dox. 430, 15.
3 Pseudo-Plut., Strom., frag. 2, Dox. 579, 17.
4 Plut., Symp., q. viii. 579, 17.
3 For a single corporeal substance Empedocles substituted four
elements specifically different, the four which became later the four
classical elements of ancient chemistry—earth, water, air, fire. His
dominant interest was to discover the efficient cause of the evolution
of things, which he believed to consist in the two great motive forces,
love and hate. Empedocles was not only a philosopher : he was also
a magician, doctor, poet, orator, and statesman. Aristotle ascribes to
him the invention of rhetoric.

D

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by the separate production of the individual organs
and members, e.g. the head, eyes, arms, which were
subsequently joined by chance in every possible
combination, of which only those have survived which
were fitted to live (cf. the Darwinian principle of
the survival of the fittest).
It is also worth remark that, before Democritus,
Anaximander and Empedocles also sought, like the
pseudo-scientific evolutionism of modern times, to
explain all things mechanically, that is to say—as the
result of a simple aggregation of material elements
effected by local motion.

(¿) Among these physicists, as Aristotle termed them,
or philosophers of sensible nature, must be reckoned
three great thinkers, Heraclitus, Democritus, and
Anaxagoras.
(i) Heraclitus of Ephesus,1 a lonely and proud genius
who despised the multitude and popular religion,
drew heroically from the thought of the Ionian
philosophers its ultimate metaphysical presuppositions,
and thereby fixed for all succeeding ages one of
the possible extremes of speculation and error. A
particular reality perceived in things had taken hold
of his intellect with such force that he became its
hopeless slave. That reality was change or becoming.
His vision was so fixed on the change which all things
undergo that he declared that change alone is real.
üávTcc psi, all things are in flux ; and men are fools to
trust in the stability of their false happiness, “ when
they are born, they wish to live and to meet their
1 The dates of Heraclitus’s birth and death are uncertain. He was
in his àKfj.71, the prime of his age, about 500 b.c.
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doom—or rather to rest—and they leave children
behind them to meet their doom in turn.” We do
not touch the same thing twice nor bathe twice
in the same river. The very moment we touch an
object, it has already ceased to be what it was before.
Whatever exists changes from the very fact of its
existence.
That is to say change has no abiding and permanent
subject identical with itself, like an ivory billiard ball
which remains an ivory billiard ball while it is in
motion. We are therefore compelled to pronounce
boldly that that which is (the thing which changes)
at the same time is not (because there is nothing which
persists throughout the change). “We step and do
not step into the same river ; we are and are not.”
Moreover, contraries must be pronounced identical.
The sea is the purest and the impurest water. Good
and ill are one. “ No one,” writes Aristotle in a
famous passage, “ can possibly conceive that the same
thing does and does not exist. According to some,
Heraclitus was of a different opinion, but we are not
obliged to believe that a man really thinks whatever
he says. The reason of the opinion held by these
philosophers was that the only realities they admitted
were sensible objects, and, since they perceived that
sensible nature is in perpetual motion, some have held
with Cratylus1 that no statement can be made about
it ; he was content to wag his finger.”1
2 This
scepticism was the inevitable consequence of Heraclitus’s
philosophy of pure flux, despite his personal conviction,
1 One of Heraclitus’s most famous disciples. He was Plato’s first
teacher. (Aristotle, Metaph., i, 6.)
2 Metaph., iv, 5, 1010 a 13.
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passionately held, of the reality and value of truth.
“ If you do not expect the unexpected,” he said, “ you
will not find truth, for it is hard to be sought out and
difficult.”
Heraclitus is thus the philosopher of evolution and
becoming. In his view, all things are differentiations
produced by discord or strife (îcôXefxoç' raxvrip tocvtcov)
of a single mobile principle which he conceives in
the form of fire, a fire ethereal, living, and divine.
So from the outset stands out in the clearest light
that fatal necessity which chains every philosophy
of pure becoming to monism1 or to pantheism} “ If,”
wrote Aristotle,123 “ you maintain that all beings are
one, you simply return to Heraclitus’s opinion. All
things are then confused, good and evil become
identical, man and the horse are one and the same
thing. But this is really to maintain not that beings
are one, but that they are nothing.”
(ii) Born within a few years of Heraclitus’s death,
Democritus of Abdera (470-361 ?), who had a more
superficial intellect and a predilection for ideas easily
comprehensible, attempted to discover in the flux of
sensible phenomena a permanent and unchanging
element ; but in his search for this unchanging
element he made use of his imagination rather than
his understanding. Therefore the sole reality he
would recognise was something which, though it is
inaccessible to the senses, can nevertheless be appre­
hended by the imagination—namely, pure geometrical
quantity as such, stripped of all qualities (colourless,
1 The doctrine that all things are one single being.
2 The doctrine which identifies the world with God.
3 Phys., i, 2, 185 b 19.

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scentless, tasteless, etc.),and possessed solely of extension
in the three dimensions of space. Democritus found
the explanation of everything in the plenum, which he
identified with being, and the void, identified with
nonentity. The plenum was divided into indivisible
parts of extension (“ atoms ”), which were separated
one from another by the void and in a state of ever­
lasting motion, and differed only in shape,1 order,12
and position.3 The order of the universe and the
structure of individual beings he attributed to the
blind necessity of chance. Thus Democritus 4 intro­
duced into Greek philosophy during the lifetime of
Socrates the doctrine of atomism and more generally
the philosophy termed mechanical, which raises
geometry to the position of metaphysics, reduces
everything to extension and motion, and professes to
explain the organisation of the universe by a host of
fortuitous coincidences. In this fashion the Parthenon
could be “ explained ” as the result of throwing
stones one on another during an indefinite term of
1 As, for example, A differs from N.
2 As AN differs from NA.
3 As N differs from the same letter placed differently : Z.
4 As also his master Leucippus. Had Leucippus and Democritus
comein anyway under the influence of the Indian philosopher Kanada?
The more likely hypothesis is a coincidence due to similarity of intellec­
tual outlook, particularly if Kanada, whose date is very uncertain, was
contemporary with or even posterior to Democritus. Speaking
generally, there seems no reason to believe that Oriental speculation
so influenced Greek thought as to teach it in the strict sense or transmit
any particular system. That, on the other hand, it influenced the
Greeks by arousing a spirit of speculative inquiry and providing in­
tellectual material (which they alone were able to treat scientifically)
is the obvious conclusion from the simple fact that Greek philosophy
originated in those provinces of the Hellenic world which were in
contact with the East.

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years, the tragedies of Racine as due to the in­
discriminate shuffling of type for a sufficient length
of time.
(iii) Finally Anaxagoras of Clazomenae (500-428),
who was a friend of Pericles, and in the maturity
of his powers when Democritus was born and
Heraclitus had just died, turned Greek philosophy
towards a higher source of illumination, and cor­
rected rather than continued the speculation of the
lonians by the aid of ideas which, it must be con­
fessed, he either worked out badly or was unable
to use.
On the one hand, he perceived that the material
principle of which all bodies are formed, and which the
lonians had identified with one particular element,
must already somehow contain in itself the entire
diversity to which it will give birth : unless everything
were in everything, nothing could come from nothing.1
He therefore concluded that the principle in question
consisted of an endless mixture of all natures and
qualities in such fashion that each corporeal particle
contained within itself the elements (homoeomeries')
of all the rest ; for example, each particle of the bread
we eat contains invisible elements of the bone, blood,
flesh, etc., which will be discovered later, changed
only in their relative proportions, in each particle of
bone, blood, flesh, etc. It was a bizarre conception,
and, as taught by Anaxagoras, not worth serious
discussion, but nevertheless a crude adumbration of
Aristotle’s great conception of first matter {materia
prima} which is nothing in act, but all bodies in
potentiality.
1 Cf Aristotle, Phys., i, 4, 187 a 26. Simplicius, Phys., 155, 23.

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On the other hand—and it is his chief claim to
distinction—he realised that the material principle,
that of which all things are made, is insufficient to
explain them. We must also discover the agent
that produces them (the efficient or motor cause) and
the end for which the agent acts (the final cause).
Is it, as Plato was to ask later, a sufficient explana­
tion of the fact that Socrates is sitting in prison
to say that he has bone, joints, and muscles arranged
in a particular fashion? We must also know who
brought about that disposition of these bones and
muscles—namely, Socrates himself by his will—and
why he willed it.
Because Anaxagoras arrived at the recognition that
there must necessarily exist, besides the material
elements of the world, a separate Intelligence (vouç1)
to which the ordering of the universe is due, he alone,
as Aristotle remarks “ kept sober ” when all the other
philosophers of his period, drunk with the wine of
sensible appearances, “ spoke at random.” 1
THE ITALIANS

Besides the school of Ionian philosophy, there
existed in the Hellenic world of the sixth and fifth
centuries b.g. two other great philosophic schools—
the Pythagorean and the Eleatic.
Pythagoras of Samos (572-500 ; according to other
authorities, 582-497), the founder of a philosophic
society of a religious and political character, which
held the reins of government in several cities of Magna
Graecia (Southern Italy), and was later dissolved by
1 Metaph., i, 3, 984 b 18.

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violence,1 understood that there existed realities of a
higher order than those perceptible by the senses.
But it was by the study of numbers that he had arrived
at the knowledge of these invisible realities, whose
immutable order dominated and determined the
process of becoming ; and henceforward he had
understanding only for numbers. Not content with
teaching that there is present in all objects and in the
universe as a whole a hidden principle of measure and
harmony, he taught that numbers—by which this
harmony is revealed to our senses—are the sole true
reality, and regarded them as the very essence of
things. Pythagoras was not only conversant with the
important observations of Oriental astronomy, but,
by his fundamental discovery of the relationship
between the pitch of sounds and the length of vibrating
strings, had reduced to the rigidity of numerical law
so fugitive a phenomenon as sound. Imagine the
awed astonishment with which he must have dis­
covered behind the flux of sensible phenomena the
intelligible constant and immaterial proportions which
explain to the mathematician the regularities we
observe. Consider, moreover, the mysterious symbolic
value of numbers attested alike by the sacred traditions
of mankind and the most positive of philosophers (from
Aristotle, who paid homage to the holiness of the
number 3, to Auguste Comte, who will construct an
entire mythology of the prime numbers), and it is easy
to understand how naturally the thought of Pythagoras
1 In this society absolute obedience prevailed even in the speculative
sphere. It was in the Pythagorean brotherhood, not in the schools of
the Christian Middle Ages, that everything yielded to the Magister
dixit, airbs tya.

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and his disciples passed from the sign to the cause and
made the symbol a principle of reality.
Consequently, numerical principles were regarded
as the principles of everything that exists ; from the
opposition between the determinate and the indeter­
minate (infinite) are derived all the fundamental
pairs of opposites—odd and even, the elements of
number, the one and the many, right and left, male
and female, rest and motion, straight and crooked,
light and darkness, good and evil, the square and
the quadrilateral with unequal sides—which determine
the nature and activity of things. Every essence has
its number and every essence is a number. The
number 4, for example, is not simply a figure ofjustice,
it constitutes the essence of justice ; similarly the
number 3 constitutes holiness, the number 7 time,
the number 8 harmony, the number 5 the union of the
sexes, the number 10 perfection. When numbers
which in themselves are not localised receive a position
in space, bodies come into existence. Thus all
speculation on the origin or nature of things resolves
itself into speculation on the genesis and properties
of numbers.
Pythagoras, therefore, and his school, to whom
mathematics, music and astronomy owe so much,
never arrived at the true conception of the first
philosophy or metaphysics. They achieved, it is true,
a degree of abstraction superior to that at which the
lonians had halted, and did not, like them, confuse
metaphysics with physics. But they confused it
with the science of number, into which, moreover,
they imported qualitative interpretations ; and, con­
sequently, in spite of their effort to reach the object
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of pure intelligence, they were held fast in the bonds
of imagination. And if, on the other hand, they
perceived that the nature of things is intrinsically
determined by immaterial principles more real and
truer than that which is tangible and visible, they
were not yet able to attain the notion of the formal
cause, whose full elucidation was reserved to Aristotle
alone.
It is to Pythagoras, as we have already remarked,
that we owe the term philosophy. A passage of Diogenes
Laertius (viii, 8) shows that for him the dignity of
science consisted in its purely speculative and dis­
interested character, a point on which Aristotle,
at the beginning of his Metaphysics, was to insist strongly.
“ Human life,” he said, “ may be compared to the
public games, which attract diverse sorts of men.
Some come to compete for honours and the crowns of
victory, others to trade, others, the more noble sort,
solely for the enjoyment of the spectacle. Similarly
in life some work for honour, others for profit, a few
for truth alone ; they are the philosophers. ...”
Pythagoras appears to have taught the unity of God,
whom he regarded as one omnipresent Spirit from
whom our spirits emanated. He was the first to give
the universe the name xóct[xo£, which, like the Latin
mundus, conveys the idea of beauty and harmony.
The most famous and the most derided of his tenets
was the doctrine of the transmigration of souls, or
metempsychosis, which he probably derived not from
Egypt, as Herodotus suggests, but from Hinduism
(by way of Persia) ;1 a doctrine which very early
1 As Gomperz observes, “ the Asiatic Greeks and a portion of the
population of India were already subject, when Pythagoras left his

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obtained in Greece the adhesion of the Orphies and
the Pythagoreans. “ Coming one day upon a puppy
which was being cruelly beaten,” the aged Xenophanes
wrote of Pythagoras in mordant verse, “ he lamented
its fate and cried out in pity ‘ Stop ! Don’t beat him.
That is the soul of one of my friends ; I recognise him
by his voice.’ ”
The Pythagoreans also believed that the revolution
of cosmic cycles must produce the everlasting recur­
rence at enormous intervals of all things, reproduced
identically even in the most insignificant details.
“ According to the Pythagoreans,” Eudemus told his
disciples, “ a day will come when you will be all
gathered again, sitting in the very same places to
listen, and I shall be telling you the same story once
more.” 1
Astronomy was among the sciences which the
Pythagorean school cultivated most successfully. Philo­
laus, who taught that the earth, the sun, and all the
stars revolved around a mysterious centre of the
universe filled with fire, may be regarded as a distant
precursor of Copernicus. But even in this sphere the
Pythagoreans betrayed in the most flagrant fashion
the vices of the exclusively mathematical mind.
native Ionia, to the same ruler, Cyrus, the founder of the Persian
Empire” [Thinkers of Greece, i, 3).
Speaking more generally, it was, it would appear, by way of the
Pythagorean school that certain distinctively Oriental conceptions and
modes of thought first entered Greece, to pass from Pythagoreanism to
Platonism and neo-Platonism, and thence, swollen by further additions,
into Gnosticism and the more or less underground stream of heterodox
speculation.
1 Simplicius, Phys., 732, 30 D. Nietzsche, who was obsessed and
driven to despair by the thought “ of the everlasting recurrence of
things,” derived this singular conception from Greek philosophy.

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“ The Pythagoreans,” wrote Aristotle,1 “ having been
brought up in the study of mathematics . . . suppose
the whole heaven to be a musical scale and a number.
All the properties of numbers and scales which they
could show to agree with the attributes and parts,
and the whole arrangement of the heavens, they col­
lected and fitted into their scheme ; if there was a
gap anywhere, they readily made additions so as to
make their whole theory coherent. For example, as
the number io is thought to be perfect and to comprise
the whole nature of numbers, they say that the bodies
which move through the heavens are ten ; but as
the visible bodies are only nine, to meet this they
invent a tenth—the counter-earth—not studying the
phenomena to discover their causes and test their
hypotheses, but imposing upon the phenomena their
hypotheses and preconceived beliefs, thereby claiming
to assist God to fashion the universe.”
THE ELEATICS

Though it cannot, strictly speaking, be said that the
school of Elea founded metaphysics, since it failed to
keep a firm grasp of the truth, it must receive the
credit of having raised Greek thought to the meta­
physical level and attained the necessary degree of
abstraction. The oldest of the Eleatics was Xeno­
phanes, a wandering rhapsodist, born about the year
57° at Colophon, whence he migrated to Elea in
southern Italy—banished, no doubt, by the Persian
invasions. Xenophanes poured scorn upon the mytho­
logy of the poets and the opinions of the common
1 Metaph., i, 5, 986 a. De Caelo, ii, 13, 293 a.

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people. “ Far better,” he said, in slighting reference
to the honours paid to athletes, “ is our art than the
strength of men and horses.” He taught the absolute
unity of God, but confounded him with the universe,
declaring in a pantheistic sense that God is one and
all, sv xat Tcav.
But the most profound thinker, indeed the true
founder of this school, was his disciple Parmenides of
Elea (born 540), the Great Parmenides, as Plato
called him. Transcending the world of sensible
phenomena and even that of mathematical forms or
essences and numbers, he attained to that in things
which is purely and strictly the object of the intellect.
For it can scarcely be denied that the first truth about
things which the intellect perceives is that they exist,
their being. The notion of being, thus abstracted,
impressed Parmenides so powerfully that it fascinated
him. As his contemporary Heraclitus was the slave
of change, Parmenides was the slave of being. He
had eyes for one thing alone : what is is, and cannot
not be ; being is, non-being is not. Parmenides was
thus the first philosopher who abstracted and formu­
lated the principle of identity or non-contradiction, the
first principle of all thought.
And as he contemplated pure being, he perceived
that this being is completely one, absolute, immutable,
eternal, without becoming, incorruptible, indivisible,
whole and entire in its unity, in everything equal to
itself, infinite1 and containing in itself every perfec­
tion.2 But while he thus discovered the attributes of
him who is, he refused to admit that any other being
1 Simplicius, Phys., 144, 25-145, 23.
2 Aristotle, Phys., i, 3.

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could exist, and rejected as a scandal to the reason
the being mingled with non-entity, because produced
from nothingness, of every creature.
He was thus led so far astray that he ascribed to
the being of the world that which belongs only to
uncreated being. And rather than be false to what
he believed were the exigencies of being and reason,
he preferred to refuse heroically the witness of the
senses and deny the existence in the universe of change
or multiplicity. Change, motion, becoming, as also
the diversity of things, are but an illusory appearance.
There exists only being, the one.
Does not change imply that an object both was
and was not (what it becomes), and at the same time
continues and ceases to be (what it was) ? Does not
multiplicity imply that what is (this) is not (that) ?
Do not, therefore, multiplicity and change contradict
the fundamental principle that what is possesses in
itself being and not non-being ?
It was in defence of Parmenides’s doctrine of the
impossibility of change that his disciple Zeno of Elea 1
(born 487) composed his famous arguments, by which
he claimed to prove that the very concept of movement
is self-contradictory : arguments fallacious, no doubt,
but of singular force and refutable only by the doctrine
of Aristotle.
Thus Parmenides, reaching the opposite pole to
Heraclitus, fixed, as he did, once for all one of the
extreme limits of speculation and error, and proved
that every philosophy of pure being, for the very
reason that it denies that kind of non-being which
1 Not to be confused with Zeno the Stoic, who lived much later
(350-264) and was born at Cittium in Cyprus.

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Aristotle termed potentiality and which necessarily
belongs to everything created, is obliged to absorb all
being in absolute being, and leads therefore to monism
or pantheism no less inevitably than the philosophy
of pure becoming.

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THE SOPHISTS AND SOCRATES

The long effort of these speculative pioneers which
we have briefly recapitulated had equipped human
thought with a number of fundamental truths. But
if, looking backwards with a knowledge of the mighty
synthesis in which all those truths, then partially per­
ceived, have been harmonised and balanced, we can
contemplate with admiration the gradual formation
of the vital centres and arteries of philosophy, at
the time, in fifth-century Hellas, these good results
were concealed not only by the medley of con­
tradictory theories, but by the number and gravity
of prevalent errors, and it seemed as though the
entire movement had achieved nothing but disorder
and chaos.
The Greek thinkers had set out with high hopes of
knowing everything, and climbing the sky of wisdom
in a single step. As a result of this immoderate
ambition, and because they lacked discipline and
restraint in handling ideas, their concepts were
embroiled in a confused strife, an interminable battle
of opposing probabilities. The immediate and obvious
result of these attempts at philosophising seemed the
bankruptcy of speculative thought. It is not, therefore,
surprising that this period of elaboration produced a
crisis in the history of thought, at which an intellectual
disease imperilled the very existence of philosophic
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speculation. This intellectual disease was sophistry,
that is to say, the corruption of philosophy.
THE SOPHISTS

Sophistry is not a system of ideas, but a vicious
attitude of the mind. Superficially the sophists were
the successors and disciples of the thinkers of an earlier
generation—even the word sophist originally bore no
derogatory significance—in reality they differed from
them completely. For the aim and rule of their
knowledge was no longer that which is, that is to say,
the object of knowledge, but the interest of the knowing
subject.
At once wandering professors accumulating honours
and wealth, lecturers, teachers of every branch of
learning, journalists, if one may so call them, supermen,
or dilettanti, the sophists were anything in the world
but wise men. Hippias, who achieved equal eminence
in astronomy, geometry, arithmetic, phonetics, pro­
sody, music, painting, ethnology, mnemotechnics, epic
poetry, tragedy, epigram, dithyramb, and moral
exhortation, ambassador of Elis, and jack-of-all-trades
(he attended the Olympic Games in clothes made
entirely by himself), reminds us of some hero of the
Italian Renaissance. Others resemble the philosophes
of the eighteenth or the “ scientists ” of the nineteenth
century. But the most characteristic feature of all
alike was that they sought the advantages conferred
by knowledge without seeking truth.
They sought the advantages conferred by knowledge
so far as knowledge brings its possessor power, pre­
eminence, or intellectual pleasure. With this in view,
e
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they put themselves forward as rationalists and
walking encyclopaedias ; to every question they had
an answer ready, deceptively convincing ;1 and they
claimed to reform everything, even the rules of
grammar and the gender of nouns.8 But their
favourite study was man, of all the most complex and
uncertain, but one in which knowledge is easiest
coined into power and reputation ; and they culti­
vated most assiduously law, history, casuistry,3 politics,
and rhetoric. They professed to be teachers of virtue.
They did not seek truth. Since the sole aim of
their intellectual activity was to convince themselves
and others of their own superiority, they inevitably
came to consider as the most desirable form of know­
ledge the art of refuting and disproving by skilful
arguments, for with men and children alike destruction
is the easiest method of displaying their strength, and
the art of arguing with equal probability the pros
and cons of every question—another proof of acumen
and skill. That is to say, in their hands knowledge
altogether lost sight of its true purpose, and what
with their predecessors was simply a lack of intellectual
discipline became with them the deliberate intention
to employ concepts without the least regard for that
delicate precision which they demand, but for the pure
1 Critias, for example, considered belief in the gods as the invention
of an astute statesman who sought to keep the citizens obedient by
clothing the truth in a garment of fiction.
2 It was Protagoras who attempted to rationalise the genders of
nouns : desiring, for example, that fiyvis (anger) should be given the
masculine gender, also
(helmet), etc.
3 Recall, for example, the celebrated discussion between Protagoras
and Pericles after an accidental homicide in the course of an athletic
contest, on the question who ought to be punished : the man who
arranged the contest, the unskilful player, or the javelin itself.

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pleasure of playing them off one against the other—
an intellectual game of conceptual counters devoid
of solid significance. Hence their sophisms or quibbles.
Their ethics were of a piece. Every law imposed
upon man they declared to be an arbitrary convention,
and the virtue they taught was in the last resort either
the art of success, or what our modern Nietzscheans
call the will to power.
Thus, of the spirit which had inspired the lofty
intellectual ambitions of the preceding age, the sophists
retained only the pride of knowledge ; the love of
truth they had lost. More ardently than their pre­
decessors they desired to achieve greatness through
knowledge, but they no longer sought reality. If we
may use the expression, they believed in knowledge
without believing in truth. A similar phenomenon
has recurred since in the history of thought and on a
far larger scale.
Under these conditions the sole conclusion which
sophism could reach was what is termed relativism or
scepticism. Protagoras of Abdera (480-410), for ex­
ample, maintained that “ man is the measure of all
things—of what is, that it is, and of what is not, that
it is not,” by which he meant that everything is
relative to the dispositions of the subject and the
truth is what appears true to the individual. And his
contemporary, Gorgias of Leontini (died 375), a famous
orator, in his book entitled Of Nature or the NonExistent, taught (i) that being is not, in other words,
that nothing exists : non-existence is non-existence,
and therefore it is—a quibble on the word is which
one day would be Hegel’s grand metaphysical game—
hence being, its contrary, is not ; (ii) that if anything
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existed we could not know it ; (iii) that if anyone
could know anything, he could not communicate his
knowledge to another.
SOCRATES

It was Socrates (469-399) who saved Greek thought
from the mortal danger into which the sophists had
brought it. Except for the fact that he took no fees
for his instruction, his manner of life was externally
the same as theirs. Like them, he spent his time in
discussions with young men, and it is not surprising
that a superficial observer, such as Aristophanes,
confused him with the sophists. In reality, he waged
against them an unrelenting war and opposed them
at every point. The sophists claimed to know
everything and did not believe in truth ; Socrates pro­
fessed ignorance and taught his hearers to seek nothing
but the truth. Thus his entire work was a work of
conversion. He reformed philosophic reasoning and
directed it to the truth, which is its proper goal.
This work was of such importance for the future of
the human intellect that it is not strange that Socrates
accomplished it as a mission divinely imposed. He
possessed not only an extraordinary power of philo­
sophic contemplation (we are informed by Aulus
Gellius and Plato that he sometimes passed entire
days and nights motionless, absorbed in meditation)
but also something which he himself regarded as
daimonic or inspired, a winged fervour, a free but
measured force, even perhaps at times an interior
instinct of a higher order, gifts suggestive of that
extraordinary assistance in regard to which Aristotle
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said that those who are moved by a divine impulse
need no guidance of human reason, since they possess
in themselves a better principle.1 He compared him­
self to a gadfly sent to sting the Athenians awake
and force upon their reason a constant examination
of conscience, a service which they repaid with hem­
lock, thus affording the aged Socrates, already on the
verge of the grave, opportunity for the most sublime
death to which merely human wisdom can lead.
(a) Socrates was not a metaphysician, but a prac­
titioner, a physician of souls. His business was not to
construct a system, but to make men think. This
was the method by which he could best conquer a
sophistry whose radical vice was not so much an error
of doctrine as a deformity of the soul.
For the chief topic of Socrates’s discussions was the
problem of the conduct of human life, the moral
problem. His ethics, as far as we can judge it by the
reports of Plato and Xenophon, seems at first sight to
have been dictated by narrowly utilitarian motives.
What I ought to do is what is good for me, and what
is good for me is what is useful to me—really useful.
But at once the need becomes evident of discovering
what is really useful to man ; and at this point
Socrates compelled his hearers to acknowledge that
man’s true utility can only be determined by reference
to a good, absolute, and incorruptible. By thus
constantly raising the question of man’s last end,2
and directing men towards their sovereign good, he
went beyond utilitarianism of every description, and,
1 Magn. Moral., vii, 8. Cf. Eth., vii, i.
2 A question which he himself seems to have answered some­
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with the full force of a sane common sense, vindicated
the supremacy of moral good and our great eternal
interests ; his ethics thus passed over into the meta­
physical sphere. In the second place Socrates proved
by every method of argument that in order to behave
rightly man’s first requisite is knowledge ; he even went
so far as to maintain that virtue is identical with
knowledge and therefore that the sinner is simply
an ignorant man. Whatever we think of this mistake,
the fact remains that for Socrates ethics was nothing
if not a collection of truths established by demonstra­
tion, a real and a genuine science. In this two­
fold character, metaphysical and scientific, of his
moral teaching, he stood in radical opposition to the
sophists, and may be regarded as the founder of ethics.
(V) But it was impossible to found scientific ethics
without defining at the same time the laws which
determine scientific knowledge of every description.
Here we reach the essence of the Socratic reform.
By returning to reason itself to study the conditions
and value of its progress towards truth, that is to say,
by the use of logical and critical reflection, Socrates
disciplined the philosophic intelligence, showed it the
attitude to adopt and the methods to employ in order
to attain truth.
The first requisite was to cleanse the mind of the
false knowledge which pretends to get to the bottom
of things with a few facile ideas. That is why he
always began by leading those whom he entangled in
the net of his questions to confess their ignorance of
that which they had been certain they knew best
(Socratic irony). But this was merely the preliminary
stage of his method. Soon the questioning began

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afresh, but its object now was to lead Socrates’s inter­
locutor, whose thought it guided in the direction
desired, to discover for himself the truth of which he
had admitted his ignorance. This was the essence
of the Socratic method, his maieutic, the art of intel­
lectual midwifery. Moreover, Socrates realised so
thoroughly that the attainment of truth is a vital
and personal activity, in which the teacher can only
assist his pupil’s intelligence, as a doctor assists nature,
but the latter is the principal agent,1 that he compared
the acquisition of knowledge to the awakening of a
memory dormant in the soul, a comparison from which
Plato was to derive his famous theory of reminiscence
(àva[xv7]<n<i).
How, then, did this maieutic form the philosophic
intellect ? By determining its proper object, teaching
it to seek the essences and definitions of things.2 Socrates
was never weary of recalling reason to this one object :
that which the subject of discussion is, what is courage,
piety, virtue, the art of ship-building or cobbling, etc.
All these have a being peculiar to themselves, an
essence or nature which the human understanding
can discover and express by a definition which dis­
tinguishes it from everything else. Because Socrates
thus required that the essential should in all cases
be distinguished from the accidental, and because he
persistently employed his intellect in the search for
essences, his philosophy may be termed the philosophy
of essences. It was no longer a question of reducing
everything to water, fire, numbers, or even absolute
being, nor yet of finding some indeterminate concept
1 Cf. St. Thomas, Sum. Theol., i, q. 117, a. I.
2 Cf. Aristotle, Metaph., xi, 4, 1078 b 17-32.

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sufficiently elastic to enfold everything like a shapeless
mantle. On the contrary, Socrates’s aim was to attain
the proper intellectual expression of everything—to
define and determine its essence by a concept applicable
only to itself.
At the same time Socrates taught the reason, if not
by a finished theory of ratiocination, or by construct­
ing, as Aristotle would construct later, a logic of
syllogism and demonstration, at least practically and
of set purpose, to employ concepts, not, as in the
barbarous word-play of the sophists, as weapons to
deliver strokes at haphazard, but in such a fashion
that they fitted exactly the outline and structure of
reality. He thus created dialectic, an instrument of
knowledge, as yet no doubt defective, but which
paved the way for the correct notion of scientific
knowledge, and was compared by Plato to the art of
the expert chef who cuts up a fowl by distinguishing
and following carefully the smallest joints of its
anatomy.
(c) Thus this unwearied disputer, for all his
superficial scepticism, possessed an invincible con­
fidence in the intellect and in science—but of an
intellect disciplined, humble in its attitude towards
reality, and a science aware of its limitations, advancing
successfully and securely in the apprehension of truth
only so far as it respected the sovereignty of the real
and was conscious of its ignorance in every direction.
In this we recognise Socrates as the teacher of the
scientific spirit, as also of the philosophy which we
shall learn to know as moderate intellectualism. By his
logical and critical work he forged the instrument
indispensable for the progress of the mind and turned
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the crisis created by sophistry to the profit and salva­
tion of reason. By his work as a teacher of morality,
he not only founded the science of ethics, but liberated
thought from the fascination of the sensible, and
unintentionally, perhaps, set philosophic speculation
on the road to metaphysics, wisdom in the strict
sense. This he did simply by raising philosophy (this
was the true significance of the Socratic demand for
self-knowledge) from exclusive occupation with the
physical universe 1 to the study of human nature and
human activities, which contain a spiritual element
of a higher order altogether than the stars or the
entire universe of matter.
But Socrates was no more than a pioneer of genius.
He gave the impulse, but never reached the goal.
When he died everything was still in the air. For
method is not enough, a systematic body of doctrine
is necessary ; and Socrates, though his teaching was
fertile in fruitful hints, possessed, apart from the
elements of ethics, no doctrine in the strict sense. The
doctrinal completion of his work and the construction
of the true philosophy were reserved for Plato and
Aristotle.
1 Parmenides himself arrived at the metaphysical conception of
being by an exclusive consideration of the corporeal universe.

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So undoctrinal was Socrates’s teaching that his
disciples developed it along very divergent lines. The
philosophers known as the minor Socratics, who seized
upon some partial aspect of the Master’s thought,
which they distorted more or less, were either moralists
pure and simple (like the Cyrenaics,1 who placed man’s
last end in the pleasure of the moment, and the
Cynics,12 who, going to the opposite extreme, deified
force of character or virtue), or logicians infatuated
by the love of argument (eristics'), like the neo-sophists
of Elis and especially of the school of Megara,3 who
tended to deny the possibility of knowledge and, by
compelling philosophers to find answers to their argu­
ments, indirectly contributed to the progress of logic.
The Megarians denied that in any judgment one thing
could be predicated of another. According to them,
this amounted to affirming that the predicate was the
subject and thus everything became identical with
1 The leading philosophers of this school were Aristippus of Cyrene,
Theodore the Atheist, Hegesias, and Anniceris.
2 The name was derived from the gymnasium in Athens (Kwótrapyes)
where Antisthenes taught. The chief Cynics were Antisthenes (born
445 B.a.), Diogenes of Sinope (400-323), and Crates of Thebes.
3 The principal representatives of the school of Elis were Phaedo
and Menedemus, of the Megarian, Euclid of Megara (not to be confused
with Euclid the geometrician), Eubulides of Miletus, Diodorus Cronos,
and Stilpo.

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everything else. Hence being exists is the sole legitimate
proposition, and the Eleatic metaphysics the only true
philosophy.
PLATO

The appellation major Socratics belongs only to
Plato, Socrates’s intellectual heir, and his disciples.
Plato (42 7 -347) ,l whose father was of royal descent
and whose mother traced her pedigree to Solon,
ambitious to reign as king in the intellectual domain,
endeavoured to combine in the powerful unity of an
original system the entire host of speculations which
he found scattered and fragmentary in the conflicting
systems of his philosophic predecessors. With him
philosophy attained her majority. But the work
which he attempted and which the Socratic reform
had made possible remained incomplete and defective.
Under the impulse of his lofty and daring genius, the
intellect soared too fast and too high, and failed to
achieve by a final victory the conquest of reality.
(a) Like Parmenides, Plato understood that the
subject of metaphysics is being itself. But he refused
to absorb everything which exists in the unity of
immutable and absolute being. And he was thus led
to the discovery of important metaphysical truths.
He perceived that, since things are more or less
perfect, more or less beautiful and good, more or less
deserving of love, and since there are things whose
goodness is mixed with evil—which in philosophic
terminology participate in goodness—there must neces1 After extensive travels, Plato settled in Athens, where he purchased
the estate of a certain Academus to be the home of his school, known
therefore as the Academy.

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sarily exist a being in which goodness, beauty, and
perfection are full and entire, unmingled with their
contraries, a being which is the ground of the beauty
and goodness of everything else. His thought thus
ascended to the true God transcending the world and
distinct from it, whom he saw as goodness itself, the
absolute good, the good, so to speak, in person. But
this was not the most prominent aspect of Platon­
ism. As we pointed out above, Socrates’s philosophy
—a philosophy rather suggested by his practice
than formulated theoretically—was the philosophy of
essences ; Plato’s philosophy was, before everything
else, the philosophy of ideas.
Socrates had shown that what we must seek and
attain at all cost are the essences of things which the
mind apprehends and expresses in a definition. What,
then, is it which the intellect perceives when it appre­
hends the essence of a man, a triangle, white, or
virtue ? Clearly man, abstracting from Peter, Paul,
John, etc., triangle, abstracting from any particular
triangle, isosceles or equilateral, and similarly white
and virtue. Moreover, the concept or idea of man or
triangle persists the same when applied to a host of
men or triangles individually different. In other
words, these ideas are universals. Further, they are
immutable and eternal in this sense, that even if, for
example, no actual triangle existed, the idea of triangle,
with all the geometrical truths it involves, would
remain eternally the same. Moreover, these ideas
enable us to contemplate, pure and unalloyed, the
humanity, triangularity, etc., in which the different
beings we know as men, triangles, etc., participate.
Failing to analyse with sufficient accuracy the nature
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of oui' ideas and the process of abstraction, and
applying too hastily his guiding principle, that what­
ever exists in things by participation must somewhere
exist in the pure state, Plato arrived at the conclusion
that there exists in a supra-sensible world a host of
models or archetypes, immaterial, immutable, eternal,
man in general or man in himself, triangle in itself,
virtue in itself, etc. These he termed ideas, which are
the object apprehended by the intellect, the faculty
which attains truth—that is to say, they are reality.
But what, then, is the status of the sensible world ?
What are we to think of the individual changing and
perishable things we see and handle ? Since they are
not the ideas, they are not reality. They are, as
Heraclitus taught, mere becoming. Plato did not
deny their existence, but regarded them as feeble
and deceptive images of reality, the object of opinion
(8ól-a), not of certain or true knowledge, fleeting as
shadows cast upon a wall. Man, therefore, captive
of the body and the senses, is like a prisoner chained
in a cave, on the wall of which he sees pass before him
the shadows of the living beings who move behind
his back in the sunlight—fugitive shadows, evading
his grasp, of the idea-substances ht by the Sun of the
intelligible world, God or the idea of the good.
But, after all, is a metaphor an explanation ? The
Platonic ideas are that in virtue of which things
possess their specific natures—man in himself or
humanity is that which makes Socrates a man, the
beautiful in itself or beauty is that which makes Alci­
biades or Callias handsome. In other words, the
Platonic ideas are the essences and the perfections of
things. But, on the other hand, they are distinct
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from things—belong, indeed, to another world. How,
then, are we to explain the relationship between things
and their ideas ? Plato replied by calling them
likenesses or participations of the ideas. But these
terms, which later will receive in Scholasticism a
profound significance, are in Plato’s system nothing
more than metaphors devoid of strictly intelligible
content. And the further question immediately arises,
why and how anything exists except ideas—that is to
say, anything not pure reality. In other words,
Plato has to explain what the thing is which partici­
pates in the ideas, receives their likeness or reflection.
Plato replied that it is matter (or the boundless,
¿OTsipov). And since the ideas are that which is, he
was compelled to regard matter as that which is not,
a sort of non-existent being : a pregnant conception
which, in Aristotle’s hands, was to be purged of all
internal contradiction, but which, as presented by
Plato, seems self-contradictory, the more so since he
confuses it elsewhere with the pure space of the
mathematician.

(¿) Undisturbed by these metaphysical difficulties,
Plato proceeded to build up, in accordance with its
inner logic, the edifice of his system. For the theory
of ideas involved an entire system of philosophy,
embracing the nature of knowledge, man, and the
physical universe.
Human knowledge was divided into two totally
different categories : imagination (ebcacffa) and opinion
(3ó£a), which are concerned with that which of its
nature cannot be the object of knowledge, the visible
and corruptible world and its deceptive shadows ; and
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intellectual knowledge (vorjcn^), which is concerned
with intelligible things and is itself subdivided into
reason (Stávoia), whose object is mathematical number,
and intellect (ytâç), which rises by means of dialectic
to the intuitive contemplation of the idea-essences
and finally of God, the super-essential good.
Plato had now to explain this intellectual knowledge,
the origin of the ideas in our minds, images of the
eternal ideas. Since these ideas cannot be derived
from the senses, which are fettered to illusion, we
must receive them immediately from on high, and
they must be innate in our soul. In a former existence,
before its union with the body, the soul beheld the
ideas and possessed intuitive knowledge. That know­
ledge still remains with us, but, clouded and darkened
by the life of the body, it abides in the soul as a
dormant memory, and it is by gradually reviving it
that the quest of wisdom enables us to reconquer our
original intuition of truth. Thus man is a pure spirit
forcibly united with a body, as it were an angel
imprisoned in the flesh {psychological dualism). The
human soul lived before it animated the body, to
which it is tied as a punishment for some pre-natal
sin, and after death it enters another body ; for, while
Plato believed in the immortality of the soul, he also
held the Pythagorean tenet of transmigration, or
metempsychosis.
Since the physical world is not an object of know­
ledge, Plato can speak of it only in fables or myths,
which he develops with all the resources of a con­
summate art, although they serve only to disguise
the impotence of his philosophy to account for material
reality.
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It is in his myths that he ascribes the production, or
rather the organisation, of the world to a demiurge—
whom, in the opinion of many commentators, he
regarded as distinct from God and inferior to him—
and expounds the queer notion that man is the origin
of all living organisms : the first men created by the
gods were of the male sex ; those who led evil lives
were changed after death into women, who, in turn,
if they continued to sin, were changed into irrational
brutes, perhaps even into plants.
In ethics Plato, like his master Socrates, but more
clearly than he, established the fundamental truth of
moral philosophy : neither pleasure nor virtue nor
any partial good, but God himself, and God alone,
is the good of man. But how does man attain his
good ? By making himself, Plato replied, as like as
possible to God by means of virtue and contemplation.
Plato also examined, though inadequately, the concept
of virtue, and outlined the theory of the four cardinal
virtues, prudence, justice, fortitude, and temperance.
He taught that it is better to suffer than commit
injustice, and in the Republic 1 he paints so sublime and
so flawless a portrait of the righteous sufferer that it is
as though he had caught a glimpse of the Divine Face.
But, as a result of his exaggerated intellectualism,
he failed to distinguish the acts of the practical from
those of the speculative intellect and identified virtue,
which requires rectitude of the will, with knowledge,
which is a perfection of the reason alone. He there­
fore misapplied the principle, in itself true, that the
will always follows the guidance of the understanding,
and maintained that sin is simply due to lack of know1 ü, 362 A.

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ledge and that no one deliberately does evil : “ the
sinner is merely an ignorant person.” The conse­
quence of this theory, which Plato did not intend, is
the denial of free will.
Plato’s sociology betrays the same idealist and
rationalist tendency which leads him to misapply
another true principle, namely, that the part exists
for the whole ; so that in his ideal republic, governed
by philosophers, individuals are entirely subordinated
to the good of the state, which alone is capable of
rights, and disposes despotically of every possible
species of property, not only the material possessions,
but even the women and children, the life and liberty,
of its citizens {absolute communism).

(c) The radical source of Plato’s errors seems to
have been his exaggerated devotion to mathematics,
which led him to despise empirical reality. They
were also due to an over-ambitious view of the scope
of philosophy, in which Plato, like the sages of the
East, though with greater moderation and discretion,
placed the purification, salvation, and life of the
entire man.
Moreover, it is on account of these false principles
latent in his system that all those philosophic dreams
which tend in one way or another to treat man as a
pure spirit can be traced directly or indirectly to
Plato.
But of Plato himself we may say that his false
principles grew in an atmosphere too pure to allow
them to yield their full fruit and poison the essence of
his thought. St. Augustine was therefore able to
extract from Plato’s gold-mine the ore of truth.
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Plato’s thought worked on a large scale and sought
to embrace all things in a single grasp. But his
superior wisdom and amazing gift of intuition pre­
vented him from fixing in a final and definite state­
men of doctrine many a speculation which floated
vaguely before his mind. Weak points on which
another philosopher would have insisted he touched
lightly. Hence what in itself is a mark of imperfec­
tion—vagueness, imprecision, hints, never worked out,
with which he is often satisfied, a method of exposition
more aesthetic than scientific, employing only meta­
phors and symbols, a method which St. Thomas with
good reason criticises severely1—was actually his safe­
guard, preserving him from a too disastrous distortion
of the truths he had discovered. From this point of
view it may be said that Platonism is false, if regarded
in esse as a fully developed system, but, if regarded in
fieri as a progress towards a goal beyond itself, of the
utmost value as a stage in the development of the
true philosophy.
ARISTOTLE

To extract the truth latent in Platonism was the
mighty reform effected by Aristotle. Aristotle success­
fully took to pieces Plato’s system, adapted to the
exigencies of reality the formal principles he had dis­
covered and misapplied, reduced his sweeping per­
spectives within the limits imposed by a sublime
common sense, and thus saved everything vital in his
1 Plato habuit malum modum docendi ; omnia enim figurate dicit et per
symbola, intendens aliud per verba, quam sonent ipsa verba. (St. Thomas, In
I De Anima, viii.)

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master’s thought. He did more : he founded for all
time the true philosophy. If he saved whatever was
true and valuable, not only in Plato, but in all the
ancient thinkers of Greece, and brought to a successful
conclusion the great work of synthesis which Plato
had attempted, it was because he definitively secured
the attainment of reality by the human intellect.
His work was not only the natural fruit of Greek
wisdom purified from Plato’s mistakes and the alien
elements included in Platonism ; it contained, com­
pletely formed and potentially capable of unlimited
growth, the body of the universal human philosophy.
Before Aristotle, philosophy may be regarded as in
an embryonic stage and in process of coming to birth.
Thenceforward, its formation complete, it was capable
of indefinite development, and knew no bounds.
Inventum philosophicum semper perfectibile.
In fact, Greek speculation after Aristotle had spent
its force, and was unable to keep firm hold of the
truth. It would receive considerable material enrich­
ment, but in essentials would deform instead of perfecting
philosophy.1
(«) For twenty years Aristotle was Plato’s disciple ;
but he was a disciple with the equipment of a formid­
able critic. No one has refuted Plato’s idealism more
powerfully than he, or more effectively demolished a
system which places the substance of things outside
themselves.
It is perfectly true that the primary object of the
intellect is, as Socrates taught, the essences of things ;
1 This is the reason why we have ended with Aristotle this introduc­
tory sketch of the history of philosophy, or more exactly of the formation
of philosophy.

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perfectly true also, as Plato had perceived, that the
essence of Peter, Paul, or John is humanity or human
nature, abstracting from the individual characteristics
peculiar to Peter, Paul, or John. But this essence as a
universal exists only in the intellect—in our mind,1
which extracts or abstracts it from the things in
which it exists individualised 1
2—and, on the other hand,
it is solely as an object of intelligence (inasmuch as it
cannot be conceived apart from certain attributes),
and not in its real existence, that it is eternal and
necessary. Therefore the essences of perishable things
possess no separate existence in the pure state, and
the entire Platonic world of archetypal ideas is
sheer fiction. The truth of the matter is, as we shall
prove later in detail, that there exists in everything an
intelligible and immaterial element, which Aristotle
calls form, in virtue of which it possesses a specific
nature or essence. But this principle is not separate
from things ; it inheres in them as one of the factors
which constitute their substance. Thus individual
objects, though mutable and mortal, are no longer
deceptive shadows ; they are reality.
If real objects of a higher order exist, none are more
immediately accessible to our knowledge. If the
sensible world be, as it were, an imperfect likeness of
the divine life of pure spirit, it is a being which
resembles another being, not a mere image which has
no existence in itself. If the world is subject to
becoming, it is not pure becoming, but contains
1 And primarily in the Divine Intellect, as the Schoolmen were to
explain, thus taking account of the truth contained in Plato’s
exemplarism.
2 Cf. St. Thomas, In I Metaph., 1. io, 158 (ed. Cathala).

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enduring and substantial realities. If there is no
science of the individual object of sense as such, never­
theless a science of sensible reality is possible, because
there exists, incarnate, so to speak, in that reality,
something intelligible and immaterial.
Thus the corporeal universe is the object not of
mere opinion, which can be expressed only by myth
and allegory, but of scientific knowledge, the science
of physics. Aristotle was the true founder of physics.1
His incomparably powerful genius viewed mobility
in the immutable light of intellect, showed that all
change obeys unchanging laws, laid bare the nature
of motion itself, of generation and corruption, and
distinguished the four species of causation operative
in the sensible world.
In language strangely trenchant and severe, he sums
up his long polemic against the doctrine of ideas.
Plato, he argues, completely misconceived the nature
of the formal cause when he separated it from things.
While he fancied “ he was stating the substance of
perceptible things,” he asserted “ the existence of a
second class of substances,” and his “ account of the
way in which they are the substances of perceptible
things is empty talk ; for ‘ sharing ’ (participating)
means nothing.” He thus made it impossible to give
a satisfactory account of nature, and, by attributing
all causation and all true reality to the ideas, he was
unable to distinguish in the activity of things the
respective parts played by the efficient and the final
1 Aristotle’s experimental physics (the science of phenomena) is a
magnificent intellectual construction totally ruined by mistakes of fact.
But his philosophical physics (the science of moving being as such)
lays down the foundations and principles of every true philosophy of
nature.

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cause. He thus neglected “ the efficient cause which
is the principle of change.” He further failed to give
any account of the cause of “ that which we see to
be the cause in the case of the arts, for the sake of
which mind and nature produce all that they do
produce.” For “ mathematics has come to be the
whole of philosophy for modern thinkers, and they
profess to explain all other things by mathematics.”
“ And as to motion, if the ideas are motionless,” there
is no archetype of motion in the world of ideas, but
in that case “ whence,” according to the Platonists,
“ did motion come ? If we cannot explain motion,
the whole study of nature has been annihilated.” 1
Refutation of the theory of ideas logically in­
volved the criticism and correction of all the other
parts of the Platonic system. In epistemology Aristotle
showed that physics, mathematics, and metaphysics,
or the first philosophy, are indeed three distinct
sciences, but that they are distinguished by their
subject-matter, not by the faculty employed, which in
all alike is reason. But his most important achieve­
ment in this sphere was to prove, by the marvellous
analysis of abstraction which dominates his entire
philosophy, that our ideas are not innate memories
of pre-natal experience, but derived from the senses
by an activity of the mind.
In psychology, if in his reaction against Plato’s
metempsychosis, and from an excessive caution, he
refrained from inquiring into the condition of the soul
after death, at least he laid the firm foundations of the
spiritualist doctrine by proving, on the one hand, in
opposition to Plato’s dualism, the substantial unity of
1 Metaph., i, 9, 992 a 25-992 b 10.

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the human being, composed of two substantial parts
incomplete and complementary, and, on the other,
against the materialists, the spiritual nature of the
operations of the understanding and will. He thus
created the only psychology capable of assimilating
and explaining the vast material accumulated by
modern experiments.
In ethics, by distinguishing between the speculative
judgment (which proceeds from the understanding
alone) and the practical judgment (which proceeds con­
jointly from the will), he showed how free will is
possible, and how the sinner does what he knows to
be evil, and drew, especially in his treatment of the
cardinal virtues and in his analysis of human acts,
the outlines of what was to be, so far as the natural
order is concerned, the ethics of Christianity.

(¿) But Aristotle must be studied, not only in his
attitude to Plato, but absolutely in his attitude to that
which is. For Plato did no more than furnish him
with the occasion to wrestle with the problem of being.
Aristotle won the match, leaving us his great concepts
of potentiality and act, matter and form, the categories,
the transcendentals, the causes, as weapons wherewith
to wage the same intellectual contest, and teaching
us, as a true master of wisdom, to rise above the
study of visible and perishable things to contemplation
of the living, imperishable reality which knows no
change. “ Immovable in its pure activity, this being
is in no way subject to change. . . . On such a prin­
ciple depend the heavens and the world of nature.
Its life is such as the best which we enjoy, and enjoy
for but a short time. For it is ever in this state, since
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its act is also pleasure—the act of the supreme intelli­
gence, pure thought thinking itself. ... If God is
always in that good state in which we sometimes are,
this compels our wonder ; and if in a better, this is
yet more wonderful. Life also belongs to God : for
the act of thought is life, and God is that act ; and
God’s essential act is life most good and eternal. We
say therefore that God is a living being, eternal and
perfect, so that life which endures everlastingly
belongs to God, for God is this life.” 1 Moreover, this
God is perfectly one, absolutely single. “ Those who
say mathematical number is first, and go on to generate
one kind of substance after another and give different
principles for each, make the substance of the universe
a mere series of episodes and they give us many
governing principles ; but the world must not be
governed badly. As Homer observed, the rule of
many is not good ; one is the ruler.” 1
23
Thus Aristotle, as Alexander of Aphrodisias remarks
in a fine passage of his Commentary on the Metaphysics,2
“ leads us from the things which are themselves on the
lowest plane, but most familiar to us, up to the Father,
who has made all things, to God the most sublime,
and proves that as the founder is the cause of the
unity of the globe and the brass, so the Divine Power,
author of unity and maker of all things, is for all
beings the cause of their being what they are.”
Aristotle’s mind was at once extremely practical
and extremely metaphysical. A rigorous logician, but
also a keen-sighted realist, he gladly respected the
1 Metaph., xii, 7, 1072 b ; 9, 1074 b 35.
2 Metaph., xii, 10, 1076 a.
3 Alexander of Aphrodisias, In Metaph., ad 1045 a 36.

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demands of the actual, and found room in his specula­
tion for every variety of being without violating or
distorting the facts at any point, displaying an intellec­
tual vigour and freedom to be surpassed only by the
crystalline lucidity and angelic force of St. Thomas
Aquinas. But this vast wealth is arranged in the light
of principles, mastered, classified, measured, and
dominated by the intellect. It is the masterpiece of
wisdom, a wisdom which is still wholly human, but
nevertheless, from its lofty throne, embraces with a
single glance the totality of things.
Aristotle, however, was a profound rather than a
comprehensive thinker. He took little care to display
the proportions and wide perspectives of his philo­
sophy ; his primary object was to apprehend by an
absolutely reliable method and with a faultless preci­
sion what in every nature accessible to human know­
ledge is most characteristic, most intimate—in short,
most truly itself. Therefore he not only organised
human knowledge, and laid the solid foundations of
logic, biology, psychology, natural history, meta­
physics, ethics, and politics, but also cut and polished
a host of precious definitions and conclusions sparkling
with the fires of reality.
It can therefore be affirmed without hesitation that
among philosophers Aristotle holds a position alto­
gether apart : genius, gifts, and achievement—all are
unique. It is the law of nature that the sublime is
difficult to achieve and that what is difficult is rare.
But when a task is of extraordinary difficulty both in
itself and in the conditions it requires, we may expect
that there will be but one workman capable of its
accomplishment. Moreover, a well-built edifice is

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usually built not on the plans of several architects,
but on the plan of a single one. If, therefore, the
edifice of human wisdom or philosophy is to be
adequately constructed, the foundations must be laid
once for all by a single thinker. On these foundations
thousands of builders will be able to build in turn,
for the growth of knowledge represents the labour of
generations and will never be complete. But there
can be but one master-builder.1
For that reason, in spite of the mistakes, de­
fects, and gaps which betray in his work the limita­
tions of human reason,2 Aristotle is as truly the
1 Descartes remarks very truly in his Discours de la Méthode : “ Works
composed of many pieces and made by the hand of several workmen
are not so perfect as those which are the work of a single individual.”
But he was wrong in believing (i) that he was the man destined to
lay the foundation of philosophy, a work which the ancients had failed
to accomplish ; (ii) that by himself he was competent—at least, given
sufficient time and experience—not only to lay the foundation of
science, but to complete the edifice ; and (iii) in rejecting contemp­
tuously the entire achievement of preceding generations, together with
the traditional wisdom of humanity. Aristotle, on the contrary,
succeeded in his task by constant criticism and analysis of his
predecessors’ thought, and by making use of the accumulated results
of human speculation in the past.
2 Aristotle is often credited with certain errors made by his disciples
or commentators, especially about the human soul and the divine
knowledge and causality. But a careful study of the text proves that
when the philosopher maintained that the intellect is separate, he
meant that it is separate from matter, not from the soul itself (çf. St.
Thomas, In III De Anima, 4 and 5), and therefore he did not deny, as is
often asserted, the personal immortality of the human soul (cf. also
Metaph., xii, 3, 1070 a 26). Nor did he teach that God is not the
efficient cause of the world and moves it only as the end, or good,
which it desires. (The passage in the Metaph., xii, 7, means simply that
God moves as final cause or object of love the intelligence which moves
the first heaven ; he does not affirm that God can act only as final cause
and has not made things. On the contrary, in Metaph., ii, 1,993 b 28, he
says that the heavenly bodies are dependent on the first cause, not only

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philosopher par excellence, as St. Thomas is the theo­
logian.1
for their motion, but for their very being. Cf. Metaph. vi, I, 1026 b 17.)
Cf. also the passage from Alexander of Aphrodisias, quoted above in
the text, in which God’s efficient causality in Aristotle’s system is
admirably brought out. As for the passage {Metaph., xii, 9) in which
Aristotle investigates the formal object of the Divine Intellect,
remarking that it is better not to know than to know certain things of
a lower order, it most certainly does not amount to the denial that God
knows the things of the world ; the statement is put forward simply to
prepare for the solution of the question discussed. That solution, as
indicated by Aristotle, is formally true, and consists in the proposition,
which St. Thomas later affirmed more explicitly, that the Divine
Intellect, because of its absolute independence, has no other formal
object than the Divine Essence itself, and therefore does not know
the things of the world in themselves, but in that essence in which every­
thing is life.
It remains true, nevertheless, that Aristotle committed serious errors
(for instance, his attempt to prove the existence of the world ab aeterno),
and was also guilty of many omissions. In particular, the doctrine of
creation, which follows with absolute necessity from his principles, is
nowhere explicitly formulated by him (indeed, no heathen philosopher
reached a clear notion of creation ex nihilo); and on those questions
which, though in themselves capable of rational proof, are most
difficult to solve without the aid of revelation—the relation of the world
to God, the lot of the soul after death—he maintained a reserve, which
was perhaps very prudent in itself, but leaves his work manifestly
incomplete.
1 Goethe, repeating the theme of Raphael’s wonderful School of Athens,
in which Plato is depicted as an inspired old man, his face turned
heavenward, Aristotle as a man in the full vigour of youth pointing
triumphantly to the earth and its realities, has drawn in his Theory of
Colours (Part 2, Ueberliefertes) a striking comparison between Plato and
Aristotle. “ Plato,” he says, “ seems to behave as a spirit descended
from heaven, who has chosen to dwell a space on earth. He hardly
attempts to know this world. He has already formed an idea of it,
and his chief desire is to communicate to mankind, which stands in
such need of them, the truths which he has brought with him and
delights to impart. If he penetrates to the depth of things, it is to
fill them with his own soul, not to analyse them. Without intermission
and with the burning ardour of his spirit, he aspires to rise and regain
the heavenly abode from which he came down. The aim of all his

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(c) Aristotle was born in 384 at Stagira, in Thrace.1
The son of a doctor, by name Nicomachus, he belonged
to the family of the Asclepiadae, descended, it was
said, from Aesculapius. At the age of eighteen he
became a pupil of Plato, whose lectures he attended
until his death (347). After Plato’s death he went to
live at Atarneus in Mysia where Hermias was king,
and from there to Mytilene. He then spent eight
years at the court of King Philip of Macedon, where
he became Alexander’s tutor. After his pupil’s acces­
sion to the throne, he settled in Athens, where he
established his school at the Lyceum (a gymnasium
consecrated to Apollo Lycaeus). He taught as he
walked to and fro with his pupils under the trees of
the Lyceum, whence the name Peripatetics (walkers)
by which his disciples became known. He spent
twelve years in Athens. When the party opposed
discourse is to awaken in his hearers the notion of a single eternal being,
of the good, of truth, of beauty. His method and words seem to melt,
to dissolve into vapour, whatever scientific facts he has managed to
borrow from the earth.
“ Aristotle’s attitude towards the world is, on the other hand, entirely
human. He behaves like an architect in charge of a building. Since
he is on earth, on earth he must work and build. He makes certain
of the nature of the ground, but only to the depth of his foundations.
Whatever lies beyond to the centre of the earth does not concern him.
He gives his edifice an ample foundation, seeks his materials in every
direction, sorts them, and builds gradually. He therefore rises like a
regular pyramid, whereas Plato ascends rapidly heavenward like an
obelisk or a sharp tongue of flame.
“ Thus have these two men, representing qualities equally precious
and rarely found together, divided mankind, so to speak, between them.”
1 “ We must remember, moreover, that Stagira, a city of Chalcidice,
was a Greek colony where Greek was spoken. It is therefore incorrect
to regard Aristotle, as he is sometimes regarded, as only half Greek.
He was a pure Hellene, as pure as Parmenides, for example, or
Anaxagoras.” (Hamelin, Le Système d’Aristote, p. 4.)

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to the Macedonians brought against him an accusation
of impiety, on the pretext of a hymn he had once
composed on the death of his friend Hermias, he
retired to Chalcis, where he died at the age of sixtythree (322).
The story is told of him that his love of study was
so great that he devised the plan of holding in his
hand, while at work, a ball of copper which, if he fell
asleep, would rouse him by falling into a metal basin.
To assist his researches Philip and Alexander placed
their vast resources at his disposal. He wrote books
to be read by the general public (dialogues), which are
all lost—Cicero praised their style in the highest
terms : flumen aureum orationis fundens Aristoteles (Acad.,
II, 38, 119)—and acroamatic books, in which he
summarised the lectures given to his disciples ; the
majority of these have survived.1
The history of these books, as related by Strabo, is
very strange, and illustrates, as aptly as Pascal’s
remark on Cleopatra’s nose, the part played by trifling
1 The following is a list of Aristotle’s works :—
i. The collection of works dealing with Logic and known collectively
by the name of Organon (instrument of scientific knowledge). They
consist of the Kar^yopiai, the Categories ; the 'ÁvaXúriKa irpórepa Kai
iiarepa, the Prior and Posterior Analytics ; the TóiriKa, the Topics ; the
II epi aopiariKÛv èXéyxwr, On Sophistic Arguments ; and the Ilepi epp/rjvetas,
On Interpretation, De Interpretatione, a treatise on the meaning of proposi­
tions, which in spite of Andronicus’s rejection must be accepted as
authentic.
ii. The Physics, ^vaiK^ aKpóaais (the authenticity of Book 7 is
doubtful), with which we must group the following treatises : On
the Heavens (De Caelo), n epl óvpavov ; On Generation and Corruption, Hepl
yeveaéws Kae tpOopas ; On the Parts of Animals, Ilepi pipwv fbpioiv ; On
the Soul, Ilepi pvxm ; On Sensation, Ilepi alatH¡aews Kai alaBrjTÛv ; On
Memory, Ilepi pifp/qs Kai avapirhaeas ; the Meteorology, MerewpoXoyitó ; the
History of Animals, n epl rà fâa laroptai (the authenticity of Book 10 is
doubtful) ; and many other treatises, several of which are of dubious

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accidents in determining the destinies of mankind.
At the philosopher’s death they were inherited together
with his library by his disciple and successor Theo­
phrastus. Theophrastus bequeathed them to a disciple
authenticity, especially the De Mundo. (The treatise on Physiognomy
is spurious, but is apparently a compilation from authentic fragments.)
iii. The Metaphysics, Tà «erà rà ¡pvauci,, of which the second book,
a IXarrov, is the work of a disciple, Pasicles of Rhodes.
iv. The Nicomachean Ethics, ’Hfttó Níxo/iá^e¡a, and the Eudemian Ethics,
’HOító
The latter work was composed, not by Aristotle, but
by Eudemus himself. To these we may add the Great Ethics (Magna
Moralia'), ’Ilflirà peyaXa, which is a résumé of the two preceding, and
therefore not written by Aristotle ; the Politics, lloXm/cà ; the Poetics,
Hept iroLririKijs ; and the Rhetoric, 'Ifcyo p-qropiKh. The treatise On
Virtues and Vices, the Economics, and the Rhetoric to Alexander are spurious.
In 1891 was discovered and published the Constitution of Athens, ’ASnratuv
iroXwela. It formed part of a collection in which Aristotle gave an
outline of the constitutions of 158 Greek states.
Of the Schoolmen who commented on the works of Aristotle, the
most important are Albertus Magnus, St. Thomas, and Silvester
Maurus, whose paraphrase and commentary following the text word
for word may still be usefully consulted. Saint Thomas wrote
commentaries : (a) on the De Interpretatione (unfinished and replaced
by Cajetan’s for lessons 3-14 of Book 2) ; (6) on the Posterior
Analytics ; (c) on the Physics ; (<Z) on the De Caelo et Mundo (St.
Thomas died before it was completed, and from Book 3, lesson 8, the
commentary was continued by his pupil, Peter of Auvergne) ; (e) on
the Generation and Corruption of Animals (St. Thomas’s unfinished
Commentary has been completed by passages borrowed from other
writers, in particular from the Commentary of Albertus Magnus) ;
(/) on the Meteorology (completed by another hand from Bk. 2, lesson it);
(g) on the De Anima (the commentary on Books 2 and 3 is by St. Thomas
himself, the commentary on Bk. 1 compiled from his lectures by one of
his pupils, Raynald of Piperno ; (A) on the Parva Naturalia (De Sensu et
Sensato, de Memoria et Reminiscentia, de Somno et Vigilia) ; (i) on the
Metaphysics (modern edition by Padre Gathala, Turin, Marietti, 1915) ;
(j) on the Nicomachean Ethics ; (k) on the Politics (completed by Peter of
Auvergne from Bk. 3, lesson 6, or, as others think from Bk. 4). Cf De
Rubeis, Dissert. 23 in vol. i, Op. Omn. S. Thomae Aq., Leonine edition.
For the writings of St. Thomas and the authenticity of his various
minor works, see Mandonnet, O.P., Des Écrits authentiques de Saint
Thomas (reprinted from the Revue Thomiste, 1909-1910) Friburg.

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named Neleus, Neleus in turn to his heirs. The
latter, fearing they might be seized for the royal
library at Pergamum, hid them in an underground
chamber. They died and the manuscripts were lost.
They remained lost for a century and a half and were
only recovered by the good fortune of a successful
book-lover. About the year 100 B.c. the descendants
of Neleus’s heirs discovered the manuscripts (in a
very bad condition, as we can well imagine) and sold
them for a large sum to a wealthy collector, Apellicon
of Teos, who published them, in a very faulty edition.
At the capture of Athens by the Romans in 86 b.c.
they came into the possession of Sulla. The gram­
marian Tyrannio had access to them and made use
of them, and finally Andronicus of Rhodes catalogued
and republished them.1 Commentaries were composed
by Alexander of Aphrodisias (second century a.d.),
also by several neo-Platonic philosophers, Porphyry
(third century), Themistius (fourth century), Sim­
plicius, and Philo (sixth century).
1 Strabo, Geog., xiii, I, 54 ; Plut. Sulla, 26. Strabo’s testimony is of
considerable weight. It has, however, been proved that some of the
most important scientific treatises of Aristotle were known to the Peri­
patetics and their opponents in the third and second centuries b.c.
We must therefore conclude that Strabo’s account is reliable in its
positive assertions, so far as the history of Aristotle’s “ acroamatic ”
manuscripts are concerned, but inaccurate, or at least exaggerated,
in its negative statements. More or less complete copies of the
Philosopher’s works must have been in circulation in the Peripatetic
school before Apellicon’s discovery. We may nevertheless agree with
Hamelin’s conclusion that “ the scientific writings of Aristotle were
little read even by the Peripatetic school in its degeneracy. Apellicon’s
discovery would have had the effect of making these works once more
fashionable.” The truth of the matter therefore would be that,
before this discovery and the works of Andronicus, Aristotle’s scientific
treatises were not indeed unknown, as Strabo says, but at any rate
little and badly known.

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The Scholastic tradition, which grew up from the
eighth century onward in the Christian West, was for
long ignorant of Aristotle’s original works, with the
exception of the Organon (the treatises on logic),
which had been translated into Latin 1 by Boethius
(480-526). But it was acquainted with his thought,
which had been transmitted and popularised at
second hand and formed an integral part of the great
philosophic synthesis of late antiquity, Platonic though
it was in the main, on which the Fathers, especially
St. Augustine, had drawn so largely in the service of
the faith. In the Christian schools Aristotle’s logic
was taught in Boethius’s translation. But it was not
until the latter part of the twelfth century that the
other writings of the Philosopher (physics, metaphysics,
ethics') began to reach the Schoolmen, mainly, it would
appear, as a result of the ardent polemic conducted
at that date by the leaders of Christian thought
against the philosophy of the Arabs, who possessed
these books together with the neo-Platonic commen­
taries in a Syrian version translated later into Arabic,
and appealed to their authority. At first the object
of considerable suspicion 1
2 on account of the source
1 Later Boethius’s work was partially lost, and it was not until after
1141 that certain books of the Organon, reintroduced from the Arabs,
began to appear in the philosophic literature of the Middle Ages,
where they formed what was then known as the Logica Nova. These
were the Prior and Posterior Analytics, the Topics, and the Sophistic
Arguments. Cf. de Wulf, Hist, de la Phil, médiévale, 2nd ed. pp. 149 sqq.
2 Censures (issued in 1210 by a council of the province of Sens which
met at Paris, and renewed in 1215, in the statute imposed on the
University of Paris by the legate Robert de Courcon, a statute confirmed
by Gregory IX in 1231 and by Urban IV in 1263) forbade the
employment of Aristotle’s writings in public lectures or private teaching.
We must remember, however, that, as M. Forget points out {Rapp, au

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from which they had been received and the mistakes
which the Arab commentators had foisted into them,
all the works of Aristotle were soon translated into
Latin, at first from the Arabic text, later 1 from the
original Greek?
Now took place the meeting of human wisdom and
divine truth, of Aristotle and the Faith. All truth
belongs of right to Christian thought, as the spoils of
the Egyptians to the Hebrews. Quaecunque igitur apud
omnes praeclara dicta sunt, nostra Christianorum sunt?
because according to that saying of St. Ambrose,
which St. Thomas delighted to quote, every truth,
whoever said it, comes from the Holy Spirit.* But someone
must actually take possession, someone must enrol in
congr. scientif. intern, des cath., Brussels, 1894), individuals remained free
to read, study, and comment on these books in private. Moreover, the
censures bound only the University of Paris. In 1229 the University
of Toulouse, founded and organised under the protection of the papal
legate himself, attracted students by announcing lectures on the books
forbidden at Paris. Finally, even at Paris, when the faculty of arts
included in its course from 1255 public lectures on the Physics and
Metaphysics, ecclesiastical authority made no attempt to interfere.
And, more significantly still, Pope Urban IV, a few years later, took
under his personal patronage William of Moerbeke’s translation of
Aristotle and St. Thomas Aquinas’s Commentaries. See Chollet,
“ Aristotélisme de la Scolastique ” in Vacant and Mangenot’s
Dictionnaire de Théologie, and de Wulf, op. cit., p. 242.
1 Some of Aristotle’s works were apparently read at first in a Latin
translation from Arabic, others in a direct translation from the Greek.
In any case it was not long before the latter entirely superseded the
former. St. Thomas used only direct versions from the Greek.
2 The best of these translations is that of the entire works of Aristotle
made between 1260 and 1270 by William of Moerbeke at the suggestion
and under the supervision of St. Thomas. It is an absolutely literal
rendering of the Greek text.
3 St. Justin, Apol., ii, 13.
4 Omne verum a quocumque dicatur, a Spiritu sancto est.

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the royal service of Christ the marvellous intellect
of Aristotle. This work, begun by Albert the Great
(1193-1280), was continued and brought to a success­
ful conclusion by St. Thomas Aquinas (1225-1274).
Its accomplishment demanded a rare conjunction of
favourable conditions—the ripe culture of the age of
St. Louis, the magnificent organisation of the Domini­
can order, the genius of St. Thomas.1 St. Thomas,
whom the Church has proclaimed Doctor par excellence,
Doctor Communis Ecclesiae, and whom she has enthroned
as the universal teacher of her schools, was not content
with transferring the entire philosophy of Aristotle to
the domain of Christian thought, and making it the
instrument of a unique theological synthesis ; he
raised it in the process to a far higher order, and, so
to speak, transfigured it.
He purged it from every trace of error—that is to
say, in the philosophic order, for so far as the sciences
of observation or phenomena are concerned, St.
Thomas was no more able than Aristotle to escape
the errors prevalent in his day, errors which do not
in any way affect his philosophy itself. He welded
it into a powerful and harmonious system ; he explored
1 For the successful performance of such a task it was also requisite
that Christian thought should have attained the high degree of elabora­
tion alike in the philosophical and theological order which it had
received from the Fathers and the Scholastic predecessors of St. Thomas.
Therefore the work of Albertus Magnus and St. Thomas was not to
change, but on the contrary to complete Christian philosophy, giving
it its mature expression. If contemporaries were primarily impressed
with the novelty of their work—-a novelty of completion, not of alteration
—the reason is that the final process which perfects a system must
always come as a shock to those who witness it, and who most likely are
attached by force of habit to certain aspects of its imperfect state as
such.

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its principles, cleared its conclusions, enlarged its
horizon ; and, if he rejected nothing, he added
much, enriching it with the immense wealth of the
Latin Christian tradition, restoring in their proper
places many of Plato’s doctrines, on certain funda­
mental points (for example, on the question of essence
and existence) opening up entirely new perspectives,
and thus giving proof of a philosophic genius as
mighty as that of Aristotle himself. Finally, and this
was his supreme achievement, when by his genius
as a theologian he made use of Aristotle’s philosophy
as the instrument of the sacred science which is, so
to speak, “ an impress on our minds of God’s own
knowledge,” 1 he raised that philosophy above itself
by submitting it to the illumination of a higher light,
which invested its truth with a radiance more divine
than human. Between Aristotle as viewed in himself
and Aristotle viewed in the writings of St. Thomas is
the difference which exists between a city seen by the
flare of a torchlight procession and the same city
bathed in the light of the morning sun.
For this reason, though St. Thomas is first and
foremost a theologian, we may as appropriately, if
not with greater propriety, call his philosophy Thomist
rather than Aristotelian.
This philosophy of Aristotle and St. Thomas is in
fact what a modern philosopher has termed the natural
philosophy of the human mind, for it develops and brings
to perfection what is most deeply and genuinely
natural in our intellect alike in its elementary appre­
hensions and in its native tendency towards truth.
1 Sum. Theol., i, q. I, a 3, ad 2.

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It is also the evidential philosophy, based on the
double evidence of the data perceived by our senses
and our intellectual apprehension of first principles—
the philosophy of being, entirely supported by and
modelled upon what is, and scrupulously respecting
every demand of reality—the philosophy of the intellect,
which it trusts as the faculty which attains truth, and
forms by a discipline which is an incomparable mental
purification. And for this very reason it proves itself
the universal philosophy in the sense that it does not
reflect a nationality, class, group, temperament, or
race, the ambition or melancholy of an individual or
any practical need, but is the expression and product
of reason, which is everywhere the same ; and in this
sense also, that it is capable of leading the finest
intellects to the most sublime knowledge and the
most difficult of attainment, yet without once betraying
those vital convictions, instinctively acquired by every
sane mind, which compose the domain, wide as
humanity, of common sense. It can therefore claim
to be abiding and permanent {philosophia perennis~) in
the sense that before Aristotle and St. Thomas had
given it scientific formulation as a systematic philo­
sophy, it existed from the dawn of humanity in germ
and in the pre-philosophic state, as an instinct of the
understanding and a natural knowledge of the first
principles of reason and ever since its foundation as
a system has remained firm and progressive, a
powerful and living tradition, while all other philo­
sophies have been born and have died in turn. And,
finally, it stands out as being, beyond comparison
with any other, one ; one because it alone bestows
harmony and unity on human knowledge—both meta100

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physical and scientific—and one because in itself it
realises a maximum of consistency in a maximum of
complexity, and neglect of the least of its principles
involves the most unexpected consequences, distorting
our understanding of reality in innumerable directions.
These are a few of the external signs which witness
to its truth, even before we have studied it for ourselves
and discovered by personal proof its intrinsic certitude
and rational necessity.

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DEFINITION OF PHILOSOPHY

We began by calling philosophy human wisdom.
Now that the history of its origins has given us further
information as to the nature and object of this wisdom,
we are in a position to attempt a more precise definition
of philosophy.
For this purpose we shall take philosophy to mean
philosophy par excellence, the first philosophy or meta­
physics. What we shall say of it in the absolute sense
(simpliciter) will be applicable relatively (secundum quid)
to the other departments of philosophy.
Philosophy is not a “ wisdom ” of conduct or
practical life that consists in acting well. It is a wisdom
whose nature consists essentially in knowing.
How ? Knowing in the fullest and strictest sense
of the term, that is to say, with certainty, and in being
able to state why a thing is what it is and cannot be
otherwise, knowing by causes. The search for causes
is indeed the chief business of philosophers, and the
knowledge with which they are concerned is not a
merely probable knowledge, such as orators impart
by their speeches, but a knowledge which compels
the assent of the intellect, like the knowledge which
the geometrician conveys by his demonstrations. But
certain knowledge of causes is termed science. Philo­
sophy therefore is a science.
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ing by reason, by what is called the natural light of the
human intellect. This is a quality common to every
purely human science (as contrasted with theology).
That is to say, the rule of philosophy, its criterion of
truth, is the evidence of its object.
The medium or light by which a science knows its
objects is termed in technical language its lumen sub
quo, the light in which it apprehends the object of its
knowledge (itself termed the object, quod}. Each of
the different sciences has its own distinctive light
{lumen sub quo, medium seu motivum formale} which
corresponds with the formal principles by means of
which they attain their object. But these different
principles are alike in this, that they are all known
by the spontaneous activity of our intellect, as the
natural faculty of knowledge, in other words by the
natural light of reason—and not, like the principles
of theology, by a supernatural communication made
to man {revelation}, and by the light of faith. We have
now to consider the object quod of philosophy.
Knowing what ? To answer this question we may
recall the subjects which engaged the attention of
the different philosophers whose teachings we have
summarised. They inquired into everything—know­
ledge itself and its methods, being and non-being,
good and evil, motion, the world, beings animate
and inanimate, man and God. Philosophy there­
fore is concerned with everything, is a universal
science.
This does not, however, mean that philosophy
absorbs all the other sciences, or is the sole science,
of which all the rest are merely departments ; nor on
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the other hand that it is itself absorbed by the other
sciences, being no more than their systematic arrange­
ment. On the contrary, philosophy possesses its
distinctive nature and object, in virtue of which it
differs from the other sciences. If this were not the
case philosophy would be a chimera, and those
philosophers whose tenets we have briefly sketched
would have treated of unreal problems.1 But that
philosophy is something real, and that its problems
have the most urgent claim to be studied, is proved
by the fact that the human mind is compelled by its
very constitution to ask the questions which the
philosophers discuss, questions which moreover in­
volve the principles on which the certainty of the
conclusions reached by every science in the last resort
depends.
“ You say,” wrote Aristotle in a celebrated dilemma,
“ one must philosophise. Then you must philosophise.
You say one should not philosophise. Then (to prove
your contention) you must philosophise. In any case
you must philosophise.” 8
1 No doubt they also studied many questions relating to the special
sciences, for the differentiation of the sciences had not been carried so
far as in modern times. Nevertheless the primary object of their study
lay elsewhere, and, at least after Socrates, those special sciences—
astronomy, geometry, arithmetic, music, medicine, and geography—
which the ancients cultivated with success developed separately, and
in clear distinction from philosophy. The very history of the special
sciences, which in modern times have made such enormous progress
independently of philosophy and as autonomous branches of study,
plainly proves that they are no part of the former.
2 “ el pièv tpiXoao^Téov, 0iXo<To^^r^or, /eat, el p.i¡ <pi\oao<[riYTéov, (pi\oao(f>rjréov, irá.vrws Üpa rpLXotrot/rrprtov.”
This dilemma is taken from the TíporpeirTiKÓs, a lost work of which
only a few fragments have come down to us. (Cf. fr. 50, 1483 b 29, 42 ;

1484 a 2, 8, 18.)

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But how can philosophy be a special science if it
deals with everything ? We must now inquire under
what aspect it is concerned with everything, or, to
put it another way, what is that which in everything
directly and for itself interests the philosopher. If, for
example, philosophy studies man, its object is not to
ascertain the number of his vertebræ or the causes
of his diseases ; that is the business of anatomy and
medicine. Philosophy studies man to answer such
questions as whether he possesses an intellect which
sets him absolutely apart from the other animals,
whether he possesses a soul, if he has been made to
enjoy God or creatures, etc. When these questions
are answered, thought can soar no higher. No
problems lie beyond or above these. We may say
then that the philosopher does not seek the explanation
nearest to the phenomena perceived by our senses,
but the explanation most remote from them, the
ultimate explanation. This is expressed in philo­
sophical terminology by saying that philosophy is not
concerned with secondary causes or proximate explana­
tions ;1 but on the contrary with first causes, highest
principles or ultimate explanations.
Moreover, when we remember our conclusion that
philosophy knows things by the natural light of reason,
it is clear that it investigates the first causes or highest
principles in the natural order.
When we said that philosophy is Concerned with
everything, everything which exists, every possible
object of knowledge, our statement was too indefinite.
We determined only the matter with which philosophy
1 That is to say, approximating to the particulars of sensible
phenomena.

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deals, its material object, but said nothing of the aspect
under which it views that object, or the attributes of
that object which it studies ; that is to say, we did
not define its formal object, its formal standpoint. The
formal object of a science is the aspect under which it
apprehends its object, or, we may say, that which it
studies primarily and intrinsically and in reference to
which it studies everything else ;1 that which philo­
sophy studies in this formal sense in things, and the
standpoint from which it studies everything else, is
the first causes or highest principles of things in so far
as these causes or principles belong to the natural
order.
The material object of a faculty, science, art, or
virtue, is simply the thing or subject-matter—without
further qualification—with which that faculty, science,
art, or virtue, deals. For instance, the material object
of chemistry is inorganic bodies ; of the faculty of sight,
objects within our range of vision. But this does not
enable us to distinguish between chemistry and
physics, which is also concerned with inorganic bodies,
or between sight and touch. To obtain an exact
definition of chemistry we must define its object as
the intrinsic or substantial changes of inorganic bodies,
and similarly the object of sight as colour. We have
now defined the formal object {objectum formale quod),
that is to say, that which immediately and of its very
nature, or intrinsically and directly, or again neces­
sarily and primarily (these expressions are equivalent
renderings of the Latin formula per se primo), is appre­
hended or studied in things by a particular science,
1 Quod per se primo haec scientia considerat et sub cujus ratione caetera omnia
cognoscit.

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art, or faculty, and in reference to which it apprehends
or studies everything else.
Thus philosophy, alone among the branches of
human knowledge, has for its object everything which
is. But in everything which is it investigates only the
first causes. The other sciences, on the contrary, have
for their object some particular province of being, of
which they investigate only the secondary causes or
proximate principles. That is to say, of all branches
of human knowledge philosophy is the most sublime.
It follows further that philosophy is in strictest truth
wisdom, for it is the province of wisdom to study the
highest causes : sapientis est altissimas causas considerare.
It thus grasps the entire universe in a small number
of principles and enriches the intellect without
burdening it.
The account we have just given is applicable in an
unqualified sense only to the first philosophy or meta­
physics, but may be extended to philosophy in general,
if it is regarded as a body of which metaphysics is the
head.1 We shall then define philosophy in general
as a universal body of sciences 2 whose formal stand1 The ancients understood by the term philosophy the sum-total of
the main branches of scientific study (physics, or the science of nature ;
mathematics, or the sciences of proportion ; metaphysics, or the science
of being as such ; logic ; and ethics). There could therefore be no
question of distinguishing between philosophy and the sciences. The
one question with which they were concerned was how to distinguish
the first philosophy, or metaphysics, from the other sciences. We, on
the contrary, since the enormous development of the special sciences,
must distinguish from them not only metaphysics (the science of
absolutely first principles) but the study of the first principles in a
particular order (for instance, the mathematical or the physical) ; and
the entire body of these constitutes what we call philosophy.
2 Only metaphysics and logic constitute a universal science speci­
fically one.

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point1 is first causes (whether absolutely first causes
or principles, the formal object of metaphysics, or the
first causes in a particular order, the formal object of
the other branches of philosophy). And it follows
that metaphysics alone deserves the name of wisdom
absolutely speaking (simpliciter), the remaining branches
of philosophy only relatively or from a particular
point of view (secundum quid).

Conclusion I.—Philosophy is the science which
by the natural fight of reason studies the first
causes or highest principles of all things—is, in
other words, the science of things in their first
causes, in so far as these belong to the natural
order.

The difficulty of such a science is proportionate to
its elevation. That is why the philosopher, just
because the object of his studies is the most sublime,
should personally be the humblest of students, a
humility, however, which should not prevent his
defending, as it is his duty to do, the sovereign dignity
of wisdom as the queen of sciences.
The perception that the sphere of philosophy is
1 Strictly speaking, there is no one formal object of philosophy,
since philosophy as a whole is not simply one, but a compound of several
distinct sciences {logic, natural philosophy, metaphysics, etc.), each
specified by a distinct formal object (ens rationis logicum, ens mobile, ens
in quantum ens—cf. Part II). But between the formal objects of the
different philosophic sciences there is something analogously common—
the fact that they study, each in its own order, the highest and most
universal causes, and treat their subject-matter from the standpoint of
these causes. We may therefore say that the highest causes constitute
the final object or the formal standpoint analogously common of
philosophy taken as a whole.

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universal led Descartes (seventeenth century) to regard
philosophy as the sole science 1 of which the others
were but parts ; Auguste Comte, on the contrary,
and the positivists generally (nineteenth century),
sought to absorb it in the other sciences, as being
merely their “ systematisation.” It is evident that
the cause of both errors was the failure to distinguish
between the material and formal object of philosophy.
Philosophy of Aristotle and St. Thomas
Philosophy and the corpus of other sciences have the
same material object (everything knowable). But the
formal object of philosophy is first causes, of the other
sciences secondary causes.
Descartes
Philosophy absorbs the
other sciences—is the whole
of science.

Auguste Comte
The sciences absorb
philosophy—there is no
philosophy.

We said above that philosophy is a science, and
that it attains certain knowledge. By this we would
not be understood to claim that philosophy provides
certain solutions for every question that can be asked
within its domain. On many points the philosopher
1 Descartes used the term “ philosophy ” in its ancient sense. For
the ancients, as for Descartes, the word denoted the entire body of
scientific knowledge. But the ancients divided philosophy thus under­
stood into several distinct sciences, among which metaphysics was
distinguished as in the fullest sense philosophy. Descartes, on the
contrary, regarded philosophy, still understood as the entire body of
scientific knowledge, as a science specifically one (of which meta­
physics, physics, mechanics, medicine, and ethics were the principal
subdivisions). He thus recognised only one science. In our view
philosophy is a body of sciences which owes its unity and distinction
from the other sciences to its formal standpoint (first causes). The
leading member of this body of sciences is metaphysics, a science
specifically one, whose formal object is universal (being qua being).

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must be content with probable solutions, either
because the question goes beyond the actual scope of
his science, for example in many sections of natural
philosophy and psychology, or because of its nature
it admits only of a probable answer, for example the
application of moral rules to individual cases. But
this element of mere probability is accidental to science
as such. And philosophy yields a greater number of
certain conclusions, and of those many more perfect,
namely, the conclusions of metaphysics, thaft any
other purely human science.

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PHILOSOPHY AND THE SPECIAL SCIENCES

We have now to define the relationship between
philosophy (particularly the first philosophy or meta­
physics) and the other sciences.
Every science is mistress in her own house, inas­
much as every science possesses the indispensable and
sufficient means of attaining truth within its own
sphere and no one is entitled to deny the truths thus
proved.
A science, however, or rather a scientist, may
happen to make a mistake in its own domain. In
such a case the science in question is no doubt com­
petent to judge and correct itself, but it is obvious
that a superior science has also the right to judge and
correct it, if the mistake should contradict one of its
own results and thus come under its jurisdiction. But
philosophy, and especially philosophy in the highest
sense, that is metaphysics, is the sovereign science.
Therefore it is competent to judge every other human
science, rejecting as false every scientific hypothesis
which contradicts its own results.
Take for example an hypothesis of physics which
appears to contradict a truth of philosophy.1 Physics
is competent to judge that hypothesis by the laws of
1 It may, for instance, be questioned whether the law of inertia, as
formulated since Galileo and Descartes, can be reconciled with the
axiom of philosophy : quidquid movetur ai alio movetur.

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physics, but philosophy is also competent to judge it
by the principles of philosophy, determining whether
and how far it really contradicts the philosophic truth
in question. (If the contradiction is real, it is evident
that the hypothesis of physics in question must be false,
for one truth cannot contradict another. The physicist
must therefore bow to the verdict of philosophy, revise
his arguments and make further experiments.1)
Let us now take a conclusion of philosophy winch
appears to contradict a truth established by physics.2
It is for philosophy to judge that conclusion in accord­
ance with the principles of philosophy, to decide
whether and how far it is really in conflict with the
physical truth in question. But physics is incompe­
tent to determine the question by the principles and
data of physics. (If the contradiction is real, it is
obvious that the alleged conclusion of philosophy is
false, for one truth cannot contradict another. The
philosopher will therefore bow, not indeed to the
verdict of physics, but to the verdict of philosophy
judging itself by means of physics, and will revise his
arguments accordingly.)
1 It is true, no doubt, that we have actually to do, not with philosophy,
but with philosophers, and that philosophers are fallible, and a philosopher
may therefore be mistaken in judging an hypothesis of physics, but
this does not prove that he has no right to judge it.
A physicist may therefore be justified in a particular case in
maintaining an hypothesis of physics against a philosopher who asserts
that it contradicts a truth of philosophy. But that is because the
evidence he possesses in support of his hypothesis convinces him that
the philosopher is mistaken in his verdict—in other words, has not
given it ut philosophus, as a mouthpiece of philosophy. But he would
not therefore be justified in denying the philosopher’s competence as
such to determine the question.
3 For example, when the philosophical doctrine offree will appears to
the mechanists to contradict the physical law of the conservation ofenergy.
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Moreover, since the laws of one science are subordi­
nate to the laws of a superior science, it clearly follows
that it is the office of the superior science to govern
the inferior. But since the principles of philosophy
(the first philosophy or metaphysics) are the absolutely
first principles of all human knowledge, they possess
an authority over the principles of all other human
sciences, which are in a certain sense dependent upon
them. That is to say, philosophy (the first philosophy
or metaphysics) governs the other sciences.
Since the principles of philosophy (the first philo­
sophy or metaphysics) are the absolutely first prin­
ciples of all human knowledge, the principles or
postulates of all human sciences are in a certain sense
dependent upon them.
They do not, it is true, depend directly on the
principles of metaphysics, as the truth of a conclusion
depends on the truth of its premisses. They are selfevident by the light of natural reason {principia per se
nota). But they are not absolutely speaking {simpliciter)
first principles. Therefore, although they carry con­
viction independently of metaphysics, nevertheless
they presuppose in fact the principles of metaphysics
and can be resolved into them. They can be known
without an explicit knowledge of the principles of
metaphysics, but they could not be true, unless the
latter were true. And in this sense they are indirectly
subordinate to the latter. For instance, the mathe­
matical axiom, two quantities which are equal to a third
quantity are equal to one another, can be resolved into the
metaphysical axiom of which it is a special case : two
beings identical with a third are identical with one another.
It is for this reason that all the sciences are said to
h
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be indirectly subordinate to metaphysics. Moreover,
they are obliged on occasion to employ the universally
valid principles of metaphysics. In this sense they
are said to be subordinate to metaphysics in a particular
aspect or relatively (secundum quid').
To govern or direct anything is to prescribe its
object or end. The sciences are not directed by philo­
sophy to their end, in the sense that they cannot
attain it without the aid of philosophy. Arithmetic,
for example, has no need of philosophy to investigate
the numerical truths which it investigates of its very
nature. Philosophy, however, assigns the distinctive
ends of the special sciences in the sense that it deter­
mines speculatively the distinctive object of each,
and what constitutes their specific unity and differen­
tiation from the rest (classification of the sciences).1
And so doing it assigns the order in which they stand
one to another. Thus all the sciences are ordered
by wisdom : sapientis est ordinare. If therefore a
science, or more correctly a scientist, should happen
to lose sight of its true object by encroaching on the
domain and rights of another science,8 it is the duty
of philosophy to redress the disorder involved. In
this capacity philosophy governs or directs the sciences
1 A problem discussed in major logic.
2 Such divagations and encroachments are only too frequent.
For example, the non-Euclidean geometries may be so treated as to
divert mathematics from its proper end. On the other hand, since
Descartes, mathematics has usurped the domain of all the sciences,
and in our time physics and chemistry are constantly encroaching upon
the domain of biology, medicine upon psychology ; while the incursions
made by physics or biology into the province of philosophy itself are
innumerable : for example, the pseudo-scientific theories of the non­
existence of final causes, the unreality of qualities, determinism, atomism, or
the biological dogmas of transformism and mechanism.

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(to these distinctive ends), not by positive prescription,
but by setting them right, if they transgress their
boundaries.
On the other hand, that knowledge in which the
mind attains its ultimate good, that is to say, the
highest knowledge, may be regarded as the common
transcendent goal towards which all the special sciences
converge. But this knowledge is bestowed by philo­
sophy—the science of first causes—which in this
capacity governs or directs the sciences in view of the
common end to which their particular objects are
subordinate. All the sciences are thus directed to
wisdom.
From all we have just said it follows that to be
proficient in the sciences it is not necessary to be a
philosopher or to base one’s work on a philosophy ;
neither need the scientist while engaged in his special
task seek advice from the philosopher or attempt to
play the philosopher himself ; but “ philosophy alone
enables the man of science to understand the position
and bearings of his special science in the sum-total of
human knowledge ” or “to acquire a notion either of
the principles implicit in all experimental knowledge
or the true foundations of the special sciences.” 1 It
follows, further, that a period in the history of human
culture in which philosophy is not allowed her rightful
suzerainty over the sciences as scientia rectrix 1
2 inevitably
ends in a condition of intellectual chaos and a general
weakening of the reasoning faculty.
Descartes, just because he absorbed all the sciences
1 T. Richard, Philosophie du raisonnement dans la science d’après Saint
Thomas, p. 14.
2 St. Thomas, In Metaph., Introduction.

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in philosophy, and regarded science as absolutely
and without qualification one, believed that the prin­
ciples of all the sciences depend directly on the principles
of the first philosophy (metaphysics). In consequence
he held that the study of the sciences and of philosophy
itself must begin with metaphysics, that is to say,
with the coping-stone of the entire edifice.
The contrary error is the belief that the principles
of science are absolutely independent of the principles of
philosophy. There is therefore no place for a scientia
rectrix, and the sciences are no longer a structure built
on a definite plan, but a formless agglomeration. It
is surprising that Auguste Comte, who wished to
reduce philosophy to a mere systematisation of the
special sciences, failed to see that this very function of
classifying and systematising the sciences (in what he
terms their objective synthesis} is only possible if philo­
sophy is a distinct science of a higher order on which
the others are in a certain respect dependent.1
Philosophy of Aristotle and St. Thomas
The principles of the special sciences are subordinate
to the principles of philosophy, but only indirectly.
Philosophy therefore governs the other sciences, but its
government is such that it may be termed constitutional.
(The special sciences are autonomous.) The study of
the first philosophy (metaphysics) should be undertaken,
not at thebeginning, but at the end of intellectual research.

Philosophy of
Descartes
The principles of the
special sciences are directly
subordinate to those of

Philosophy of those who reject
Philosophy
The principles of the
special sciences are not
subordinate to the prin-

1 For Comte, indeed, sociology takes the position of scientia rectrix,
only, however, as ordering the sciences in reference to the human
subject, not in themselves. {Subjective synthesis.}

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philosophy.
The latter
therefore exercises over the
other sciences a govern­
ment which may be termed
despotic.
The study of the first
philosophy (metaphysics)
should be undertaken at
the beginning of intellec­
tual research.

ciples of any science of a
higher order. These sci­
ences therefore are in no
sense governed but are in
a condition which may be
termed anarchy. There is
no supreme science or first
philosophy (metaphysics).

Finally, if a science bases its demonstrations on
certain postulates or data, which it can neither explain
nor defend, there must be a superior science whose
function it is to defend these postulates or data. In
this sense the science of architecture defends that of
building. It is, however, obvious that every science,
except the highest, bases its demonstrations on postu­
lates or data it is incapable of explaining or defending.
For instance, mathematics does not inquire what is
the nature of quantity, number, or extension, nor
physics what is the nature of matter. And if an
objector should deny that the sensible world exists, that
two quantities equal to a third are equal to one another, or
that space has three dimensions, neither physics nor
mathematics can refute his objection, since they on
the contrary assume these postulates or data. There­
fore it must be the function of philosophy (the first
philosophy or metaphysics) to defend against every
possible objection the postulates of all the human
sciences.
It is from common sense, or from the natural
evidence of the intellect and experience, that the
sciences derive their postulates. This is no doubt their
sufficient warrant to build on these postulates, but it
is insufficient to safeguard and protect them against
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errors which call the postulates in question. And it is
also insufficient to provide for the perfecting stability
and essential needs of human knowledge. Human
knowledge would remain excessively imperfect and
weak, and would fail to reach its final end, if the
postulates of the sciences were not scientifically
explained, discussed, and defended.

Philosophy, therefore, and particularly the first
philosophy or metaphysics, because it is wisdom and
the supreme science, judges, governs, and defends the
other sciences. But the ruler is certainly not dependent
upon those whom he governs. We therefore conclude
that philosophy is independent of the inferior sciences,
or at any rate depends on them only in the sense that
a superior, when he is not strong enough to be selfsufficient, depends on the servants or instruments
which he employs. It was for this reason that
Aristotle regarded philosophy as the science pre­
eminently free.

Philosophy appeals to the facts, the data of experi­
ence. To obtain the necessary materials it uses as
instruments the truths provided by the evidence of
the senses and the conclusions proved by the sciences.
It depends on both, as a superior who cannot do his
own work depends on the servants he employs.
A dependence of this kind is a purely material
dependence, since the superior depends on the inferior
to be served by him, not to do him service. He
therefore judges by his own light of whatever his
servants bring him to supply his needs. For example,
one of the most successful students of bees, François
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Huber, who was blind, interpreted by the light of his
intellect the facts seen by his servants’ eyes.
But further, this purely material dependence of
philosophy, though absolutely necessary in respect of
the evidence of the senses, is relative and contingent
in respect to the conclusions of the sciences. It is in
fact from the evidence of the senses that philosophy
derives the fundamental principles which—interpreted
by its own light—it employs as premisses in its demon­
strations and as the means to prove its special truths.
For instance, the truth, perceived by the senses and
interpreted by the light of philosophy, there is motion
in the universe, served Aristotle as the premiss from
which he proved that being is divided into act and
potentiality, and that there is a first mover that is
pure act (God). It is obvious that philosophy is
absolutely unable to dispense with data of this kind,
and that the data thus employed as premisses must
be absolutely true. Otherwise the conclusions which
philosophy deduces from them would be uncertain.
But it is otherwise with the propositions and conclusions
of the sciences. No doubt these conclusions, if true,
contribute to the store of materials utilised by philo­
sophy—but philosophy (and particularly the first
philosophy or metaphysics) is under no necessity to
employ them, indeed ought not to employ them to
establish its own conclusions, at any rate not its certain
conclusions, though it may make use of them as
confirmatory evidence. It must certainly have at
its disposal some scientific conclusions, indeed as
plentiful a supply as possible, because it cannot
develop its principles satisfactorily until it sees them
embodied, so to speak, in concrete examples which

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the senses can perceive. But it does not need one
particular scientific proposition rather than any other,
provided, that is to say, that, true to its own nature
and maintaining the liberty due to a superior science,
it draws its proofs from its own principles and from
the fundamental truths supplied by the evidence of
the senses and not from the conclusions supplied by
the sciences. These latter, in fact, should not be
premisses but simply illustrations which assist philo­
sophy to attain its own truths. A sound philosophy
can therefore dispense with the particular system of
scientific explanations of which it makes use in accord­
ance with the state of science at a particular epoch,
and if that system were one day proved false the
truth of that philosophy would not be affected. Only
its language and the sensible illustrations with which
it clothed its truths would require modification.
These remarks are important. They show how the
datum of experience on which philosophy is primarily
based suffices for the requirements of a supreme and
universal science. This datum is provided by an
instrument—the evidence of the senses—earlier than
scientific observation, infinitely more certain than the
inductions of the sciences, and placed by nature at
the disposal of every man, and consists of truths so
simple that they are universally and absolutely valid,
so immediate and evident that their certainty exceeds
that of the best established scientific conclusions.1
1 To this fundamental datum we may add—but as secondary matter
and at times valuable confirmation—the facts of a more special
description, discovered, controlled, and measured by the observations
and experiments of science. We should bear in mind that the
absolutely evident truths which constitute the primitive and funda­
mental datum of philosophy must be carefully distinguished from

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From what has been said we can also understand
why the purely scientific mistakes to be found in
older statements of Aristotelian and Thomistic philo­
sophy, statements which inevitably bear the stamp
of the scientific beliefs of their period, do nothing to
discredit the truth of that philosophy. For no philo­
sophy has observed more faithfully than that of
Aristotle and St. Thomas the laws of thought which
guarantee its purity and freedom.
On the other hand philosophy, though distinct
from the special sciences, is not unrelated to or
isolated from them. On the contrary, it possesses the
duty to exercise its office as scientia rectrix by con­
stantly throwing its light on the discoveries and
hypotheses, the unceasing activity and the development
of the sciences, and one of the most essential requisites
for its life and progress in the world is to maintain an
intimate contact with the lower branches of study
whose data it interprets and renders fruitful.
To the extent to which philosophy thus concerns
itself with interpreting by the aid of its own truths the
facts or hypotheses which positive science regards as
proved, the errors or lacunae of positive science may
introduce accidentally into a true system of philosophy
elements of error which are, so to speak, the token and
price of the human development of philosophy—but
certain interpretations of experience drawn from unscientific
observation which are nothing more than pseudo-scientific statements.
If, for example, in natural philosophy, to prove the reality of
substantial change, it were argued that whereas water is a liquid body,
hydrogen and oxygen are gaseous bodies, the argument would rest, not
on a truth attested by the senses, but on a scientific error, for in reality
the same inorganic bodies are found in the three states solid, liquid,
and gaseous. Obviously an adequate scientific training helps the
philosopher to avoid pitfalls of this kind.

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they can only falsify a philosophy itself to the extent
to which it is untrue to its own nature and enslaves
itself to the lower branches of study.1
It is clear from everything which has been said that
the nature and needs of philosophy make it incumbent
upon the philosopher to keep himself as fully ac­
quainted as he can with the scientific knowledge of his
period, provided, however, that he preserves intact
the freedom of philosophic truth. For though the
philosopher as such need not use the affirmations of
the special sciences to establish his own truths, he
ought to make use of them, (i) to illustrate aptly his
principles, (ii) to confirm his conclusions, (iii) to
interpret, throw light upon, and assimilate, the
assured results of the sciences so far as questions of
philosophy are involved. And finally he should use
the affirmations of science (iv) to refute objections and
errors which claim support from its results.
From yet another point of view the study of the
sciences is necessary for the philosopher : his own
education must of necessity, owing to the very condi­
tions of human nature, be a progress from the imperfect
to the perfect, so that before undertaking the study of
wisdom he should undergo the training of the sciences?
1 The “ crime ” of the decadent Scholastics of the sixteenth and
seventeenth centuries was that they believed, and made others believe,
that the philosophy of Aristotle and St. Thomas was in this sense bound
up with the mistakes of ancient science, of which it is in reality wholly
independent.
2 The philosopher also requires a scientific training to be in a position
to distinguish readily between the primary evidence of experience and
certain popular but really pseudo-scientific interpretations of experience,
such, for example, as the hypothesis of the sun’s motion around the
earth or the over-hasty belief that a particular inorganic body is
essentially liquid and another essentially solid or gaseous.

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It is not therefore surprising that all the great
philosophers have been thoroughly acquainted with
contemporary science. Some have even been great
scientists (for example Aristotle, Albertus Magnus, and
Leibniz), and several scientific discoveries of the first
magnitude has been made by philosophers, for instance
the mathematical discoveries of Pythagoras, Descartes,
and Leibniz.
In this connection we may observe that a profound
and practical knowledge of a single science with which
the student is directly acquainted contributes far more
to a philosophic training than a superficial and second­
hand knowledge of a large number. Though owing
to the degree to which specialisation has been carried
in modern times he cannot hope ever to possess that
complete knowledge of all the sciences which is
possessed by the scientist in his particular department,
the philosopher should nevertheless aim at acquiring
a sufficiently thorough knowledge of the entire body
of the sciences, an ideal in itself not beyond the bounds
of possibility, as is proved by the example of several
powerful minds.
Conclusion II.—Philosophy is the highest of all
branches of human knowledge and is in the true
sense wisdom. The other (human) sciences are
subject to philosophy, in the sense that it judges
and governs them and defends their postulates.
Philosophy on the other hand is free in relation
to the sciences, and only depends on them as the
instruments which it employs.

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PHILOSOPHY AND THEOLOGY

Philosophy is the highest of the human sciences, that
is, of the sciences which know things by the natural
light of reason. But there is a science above it. For
if there be a science whch is a participation by man
of the knowledge proper to God himself, obviously
that science will be superior to the highest human
science. Such a science, however, exists ; it is
theology.
The word theology means the science of God. The
science or knowledge of God which we can attain
naturally by the unassisted powers of reason, and
which enables us to know God by means of creatures
as the author of the natural order, is a philosophic
science—the supreme department of metaphysics—
and is known as theodicy or natural theology. The know­
ledge or science of God which is unattainable naturally
by the unassisted powers of reason, and is possible
only if God has informed men about himself by a
revelation from which our reason, enlightened by
faith, subsequently draws the implicit conclusions, is
supernatural theology or simply theology. It is of this
science that we are now speaking.
Its object is something wholly inaccessible to the
natural apprehension of any creature whatsoever,
namely, God known in himself, in his own divine life,
or in technical language sub ratione Deitatis, not, as in
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natural theology, God as the first cause of creatures
and the author of the natural order. And all theo­
logical knowledge is knowledge in terms of God thus
apprehended, whereas all metaphysical knowledge,
including the metaphysical knowledge of God, is
knowledge in terms of being in general.
The premisses of theology are the truths formally
revealed by God {dogmas or articles of faith), and its
primary criterion of truth the authority of God who
reveals it.
Its light is no longer the more natural light of
reason, but the light of reason illuminated by faith,
virtual revelation in the language of theology, that is to
say, revelation in so far as it implicitly (virtually)
contains whatever conclusions reason can draw
from it.
Alike by the sublimity of its object, the certainty
of its premisses, and the excellence of its light, theology
is above all merely human sciences. And although it
is unable to perceive the truth of its premisses, which
the theologian believes, whereas the premisses of
philosophy are seen by the philosopher, it is never­
theless a science superior to philosophy. Though, as
St. Thomas points out, the argument from authority
is the weakest of all, where human authority is con­
cerned, the argument from the authority of God,
the revealer, is more solid and powerful than any
other.1
And finally as the object of theology is he who is
above all causes, it claims with a far better title than
1 Licet locus ab auctoritate, quae fundatur super ratione humana, sit
infirmissimus, locus tamen ab auctoritate quae fundatur super revelatione divina
est efficacissimus. St. Thomas, Sum. Theol. i, q. i, a 8, ad 2.

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metaphysics the name of wisdom. It is wisdom par
excellence.1 What relations, then, must obtain between
philosophy and theology ?

As the superior science, theology judges philosophy
in the same sense that philosophy judges the sciences.1
23
It therefore exercises in respect of the latter a function
of guidance or government, though a negative govern­
ment, which consists in rejecting as false any philosophic
affirmation which contradicts a theological truth. In
this sense theology controls and exercises jurisdiction
over the conclusions maintained by philosophers.

The premisses of philosophy, however, are independent
of theology, being those primary truths which are
self-evident to the understanding, whereas the premisses
of theology are the truths revealed by God. The
premisses of philosophy are self-supported and are not
derived from those of theology. Similarly the light
by which philosophy knows its object is independent
1 Theology is theoretical wisdom, par excellence the wisdom which
knows!God by the intellect and its ideas, that is to say, by the normal
processes of human knowledge. There is another wisdom of a still
higher order which is a gift of the Holy Spirit, and enables us to know
God experimentally and by means of charity. It enables us to judge
of divine things instinctively, as the virtuous man judges of virtue
{per modum inclinationis), not scientifically as the moralist judges of
virtue {per modum cognitionis). Cf. St. Thomas, Sum. Theol. i, q. i, a 6,
3.
2 See above, pp. 111 sqq. The philosopher and the scientist are never
entitled to deny the rights which theology possesses over philosophy
and the sciences. They may, however, be justified in rejecting in a
particular instance, not indeed the authority of the Church, but the
judgment of an individual theologian, since the individual theologian
does not necessarily speak as the mouthpiece of theology, and may
therefore be mistaken.

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of theology, since its light is the light of reason, which
is its own guarantee.1 For these reasons philosophy
is not positively governed by theology,1
23 nor has it
any need of theology to defend its premisses (whereas
it defends those of the other sciences). It develops
its principles autonomously within its own sphere,
though subject to the external control and negative
regulation of theology.
It is therefore plain that philosophy and theology
are entirely distinct, and that it would be as absurd
for a philosopher to invoke the authority of revelation
to prove a philosophical thesis as for a geometrician
to attempt to prove a theorem by the aid of physics,
for example, by weighing the figures he is comparing.
But if philosophy and theology are entirely distinct,
they are not therefore unrelated, and although philo­
sophy is of all the human sciences pre-eminently the
free science, in the sense that it proceeds by means
of premisses and laws which depend on no science
superior to itself, its freedom—that is, its freedom to
err—is limited in so far as it is subject to theology,
which controls it externally.
In the seventeenth century the Cartesian reform
1 This light is its own evidence and in philosophy is sufficient of
itself. But this does not prevent it serving also—in theology, however,
not in philosophy—as the instrument of a superior light ; neither, of
course, does it imply that human reason is not subordinate in its very
principles to the First Intellect.
3 Theology can turn the investigations of philosophy in one direction
rather than in another, in which case it may be said to regulate
philosophy positively by accident (per accidens). But absolutely speaking
theology can regulate philosophy only negatively, as has been explained
above. Positively it does not regulate it either directly, by furnishing
its proofs (as faith for apologetics), or indirectly, by classifying its
divisions (as philosophy itself classifies the sciences).

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resulted in the severance of philosophy from theology,1
the refusal to recognise the rightful control of theology
and its function as a negative rule in respect of philo­
sophy. This was tantamount to denying that theology
is a science, or anything more than a mere practical
discipline, and to claiming that philosophy, or human
wisdom, is the absolutely sovereign science, which
admits no other superior to itself. Thus, in spite of
the religious beliefs of Descartes himself, Cartesianism
introduced the principle of rationalist philosophy,
which denies God the right to make known by revela­
tion truths which exceed the natural scope of reason.
For if God has indeed revealed truths of this kind,
human reason enlightened by faith will inevitably
employ them as premisses from which to obtain further
knowledge and thus form a science, theology. And if
theology is a science, it must exercise in respect of
philosophy the function of a negative rule, since the
same proposition cannot be true in philosophy, false
in theology.2
1 It may, it is true, be replied that Descartes’s intention was simply
to emancipate philosophy from the authority of a particular theological
system—Scholasticism—which he regarded as worthless, because it
took its philosophic or metaphysical principles from Aristotle.
In reality, however, it was with theology itself that he broke, when he
broke with Scholasticism, which is the traditional theology of the
Church. And moreover his conception of science implied the denial
of his scientific value of theology. In any case the result of his reform
was the assertion of the absolute independence of philosophy in relation
to theology. (Cf. Blondel, “ Le Christianisme de Descartes.” Revue
de Métaph. et de Morale, 1896.)
2 The theory of a double truth, by which the same thing may be
true in philosophy, but false in theology, was invented by the mediaeval
Averroists, who sought in this way to evade the censures of the Church.
In various forms it has been revived in modern times by all who, like the
modernists, wish to keep the name of Catholics while freely professing
in philosophy opinions destructive of some particular dogmatic truth.

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On the other hand, philosophy renders to theology
services of the greatest value where it is employed by
the latter. For in fact theology employs in its
demonstrations truths proved by philosophy. Philo­
sophy thus becomes the instrument of theology, and
it is in this respect and in so far as it serves theological
argument that it is called ancilla theologiae. In itself,
however, and when it is proving its own conclusions,
it is not a bond-servant but free, subject only to the
external control and negative ruling of theology.

As was shown above, philosophy is from the very
nature of things obliged to employ as an instrument
the evidence of the senses, and even, in a certain
fashion, the conclusions of the special sciences. Theo­
logy, considered in itself as a science subordinate to
the knowledge of God and the blessed, is not in this
way obliged to make use of philosophy, but is absolutely
independent.
In practice, however, on account of the nature of
its possessor, that is to say, on account of the weakness
of the human understanding, which can reason about
the things of God only by analogy with creatures, it
cannot be developed without the assistance of philo­
sophy. But the theologian does not stand in the same
relation to philosophy as the philosopher to the
sciences.1 We have seen above that the philosopher
1 This distinction between the relationship of theology to philosophy
and that of philosophy to the special sciences derives from the fact that,
since theology is a participation of the divine wisdom, the human
subject is too weak for its unaided study and to draw conclusions from
it is compelled to employ as premisses conclusions established by an
inferior discipline.
Since, however, philosophy is a human wisdom, at which reason can
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should employ the propositions or conclusions which
he borrows from the sciences, not to establish his own
conclusions (at any rate not conclusions for which
metaphysical certainty is claimed), but merely to
illustrate his principles, and therefore that the truth
of a metaphysical system does not depend on the
truth of the scientific material it employs. The
theologian, on the contrary, makes use at every turn
of philosophic propositions to prove his own conclu­
sions. Therefore a system of theology could not
possibly be true if the metaphysics which it employed
were false. It is indeed an absolute necessity that
the theologian should have at his disposal a true
philosophy in conformity with the common sense of
mankind.
Philosophy taken in itself normally precedes theo­
logy. Certain fundamental truths of the natural order
are indeed what we may term the introduction to the
faith (praeambula fidei). These truths, which are
naturally known to all men by the light of common
sense, are known and proved scientifically by philo­
sophy. Theology, being the science of faith, pre­
supposes the philosophical knowledge of these same
truths.
Philosophy considered as the instrument of theology
serves the latter, principally in three ways. In the
first place theology employs philosophy to prove the
truths which support the foundations of the faith in
that department of theology which is termed apoloarrive, though with difficulty, by its unassisted natural power, the
human mind should be able to draw from it certain conclusions
(especially metaphysically certain conclusions) without employing as
premisses the conclusions of sciences to which it is superior in dignity
and in certainty.

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getics,1 which shows, for example, how miracles prove
the divine mission of the Church ; secondarily to
impart some notion of the mysteries of faith by the
aid of analogies drawn from creatures—as for instance
when theology uses the philosophic conception of
verbum mentale, the mental word,2 to illustrate the
dogma of the Trinity ; and finally to refute the
adversaries of the faith—as when theology shows by
means of the philosophic theory of quantity3 that the
mystery of the Eucharist is in no way opposed to
reason.
We must not forget that, if philosophy serves
theology, it receives in return valuable assistance
from the latter.
In the first place, so far as it is of its nature subject
to the external control and negative ruling of theology,
it is protected from a host of errors ; and if its freedom
to err is thus restricted, its freedom to attain truth is
correspondingly safeguarded?
In the second place, in so far as it is the instrument
of theology, it is led to define more precisely and
with more subtle refinements important concepts and
theories which, left to itself, it would be in danger of
neglecting. For example, it was under the influence
1 See Garrigou-Lagrange, De Revelatione, i, 2, 1918.
2 A theory studied in psychology.
3 An explanation given by cosmology.
4 Unassisted reason can indeed avoid error on any particular
point whatsoever within the sphere of philosophy, but in view of the
weakness of human nature it is unable without the assistance of grace
to avoid error on some point or other ; that is to say, without a special
grace or the negative control of revelation and theology it cannot
achieve a perfect human wisdom. (Cf. St. Thomas, Sum. Theol., i, q. I,
a. i ; Sum. contra Gent., i, 4 ; Garrigou-Lagrange, De Rev., i, pp. 411

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of theology that Thomism elaborated the theory of
nature and personality, and perfected the theory of the
habitus, habits, etc.

Conclusion III.—Theology, or the science of
God so far as He has been made known to us by
revelation, is superior to philosophy. Philosophy
is subject to it, neither in its premisses nor in its
method, but in its conclusions, over which
theology exercises a control, thereby constituting
itself a negative rule of philosophy.

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PHILOSOPHY AND COMMON SENSE

we know things with a scientific or perfect
knowledge by reflecting upon them and by their
causes, we know them imperfectly {unscientific know­
ledge, the knowledge of everyday life). We must
remember that we are obliged not only to begin with
this unscientific knowledge of everyday life ; we must
be content with it to the end, improving it more or
less by study and reading, in that enormous number
of cases where science in the strict sense is unattain­
able.
For, so far as the knowledge of secondary causes is
concerned, no man can possibly attain, with the per­
fection required of the genuine scientist, universal
knowledge ; in other words, he cannot specialise in
all branches of science, a contradiction in terms. He
is fortunate, indeed, if he can make himself master of
a single science. For all the others he must be satisfied
with a knowledge which, however enriched and
improved it may be in the case of what is known as
a cultivated man, that is to say, a man well acquainted
with the scientific knowledge of other people, is always
inferior to science in the strict sense. But in the
domain of first causes, the science of all things is within
a man’s grasp, for it is precisely the distinguishing
character of the science called philosophy to know

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all things by their first causes,1 and it is to the philo­
sopher or the sage, the wise man, that we have the
right to apply Leonardo da Vinci’s aphorism : facile
cósa e farsi universale ; it is easy for a man to make
himself universal.
Ordinary knowledge consists for the most part of
mere opinions or beliefs, more or less well founded.
But it implies a solid kernel of genuine certainties in
which the philosopher recognises in the first place data
of the senses (for example, that bodies possess length,
breadth, and height), secondly, self-evident axioms (for
example, the whole is greater than the part, every event has
a cause, etc.), and thirdly, consequences immediately
deducible from these axioms (proximate conclusions).
These certainties which arise spontaneously in the
mind when we first come to the use of reason are thus
the work of nature in us, and may therefore be called
an endowment of nature 1
2 as proceeding from the
natural perception, consent, instinct, or natural sense
of the intellect. Since their source is human nature
itself, they will be found in all men alike ; in other
words, they are common to all men. They may
therefore be said to belong to the common perception,
consent, or instinct, or to the common sense of mankind.
The great truths without which man’s moral life is
impossible—for example, knowledge of God’s existence,
the freedom of the will, etc.—belong to this domain of
1 It is therefore obvious what a stupendous delusion is involved in
the positivist view of philosophy. Were philosophy merely the
co-ordination or systematisation of the sciences, its attainment would
presuppose a perfect mastery of all the sciences, that is to say, specialisa­
tion in every science, which amounts to saying that philosophy is beyond
the reach of man.
2 Kleutgen, La philosophie scolastique, i, p. 439.

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common sense, as consequences immediately deducible
(proximate conclusions) from primary data appre­
hended by observation and first principles apprehended
by the intellect. All men, unless spoiled by a faulty
education or by some intellectual vice, possess a
natural certainty of these truths. But those whose
understanding has never been cultivated are not
able to give any account or at least any satisfactory
account of their convictions ; that is to say, they
cannot explain why they possess them.
These certainties of common sense, conclusions of
an implicit reasoning, are as well founded as the
certainties of science. But their possessor has no
knowledge, or an imperfect knowledge, of the grounds
on which he bases them. They are therefore imperfect
not in their value as truth but in the mode or condition
under which they exist in the mind.
Of the self-evident truths (i/ze whole is greater than
the part, every event has a cause, etc.) which are the object
of what is termed the understanding ofprinciples, and whose
certainty is superior to that of any conclusion of science,
common sense possesses a knowledge whose mode is
equally imperfect, because it is confused and implicit.
Common sense therefore may be regarded as the
natural and primitive judgment of human reason,
infallible, but imperfect in its mode.
The wholly spontaneous character of common
sense, and its inability to give an account of its con­
victions, have led certain philosophers to regard it
as a special faculty purely instinctive and unrelated
to the intellect (the Scottish school, end of eighteenth
and beginning of nineteenth century ; Reid, Dugald
Stewart, and in France, Jouffroy), or as a sentiment
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distinct from and superior to reason (the intuitive or
sentimentalist school ; for instance, Rousseau, Jacobi,
and in our own time Bergson). But in that case it
would necessarily be blind, for we possess no other
light than that of the intellect or reason. The light
of common sense is fundamentally the same light as
that of science, that is to say, the natural light of the
intellect. But in common sense this light does not return
upon itself by critical reflection, and is not perfected by
what we shall learn to know as a scientific habit {habitus').

We must now define the relations which obtain
between philosophy and common sense.
Philosophy cannot, as the Scottish school main­
tained, be founded on the authority of common sense
understood simply as the common consent or universal
witness of mankind, or as an instinct which in fact
compels our assent. For it is in fact founded on
evidence, not on authority of any kind.
But if by common sense we understand only the
immediate apprehension of self-evident first principles, which
is one of its constituents, we may say with truth that
it is the source of the whole of philosophy. For the
premisses of philosophy are indeed the evident axioms
which in virtue of its natural constitution implant in
the mind its primary certainties.
It is important to be quite clear that, if philosophy
finds its premisses already enunciated by common
sense, it accepts them not because they are enunciated
by common sense, or on the authority of common
sense understood as the universal consent or common
instinctj'of mankind, but entirely and solely on the
authority of the evidence.
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SENSE

Finally, if we take into account the entire body of
truths (premisses and conclusions) known by common
sense with certainty but in an imperfect mode, we
must conclude that philosophy is superior to common
sense, as the perfect stage of anything (in this case the
scientific stage of knowledge) is superior to the im­
perfect or rudimentary stage of the same thing (in
this case the pre-scientific stage of the same knowledge,
which is yet true and certain at both stages).
If in common sense we consider not the conclusions
which it reaches but the premisses alone, it is still
inferior to philosophy in respect of its mode of know­
ledge, but superior alike to philosophy and to all the
sciences in respect of its object and of the light in which
it knows. For, as we have said above, philosophy and
all the sciences are ultimately founded on the natural
evidence of first principles (to which philosophy
returns—in criticism—to study them scientifically,
whereas the other sciences are content to accept them
from nature).
Philosophy studies scientifically the three categories
of truths to which common sense bears instructive
witness : (i) the truths of fact which represent the
evidence of the senses ; (ii) the self-evident first prin­
ciples of the understanding, in as much as it clears up
their meaning by critical reflection and defends them
rationally ; (iii) the consequences immediately de­
ducible (proximate conclusions) from these first
principles, inasmuch as it provides a rational proof
of them. And, further, where common sense yields
to the mere opinions of popular belief, philosophy
continues to extend indefinitely the domain of scientific
certainty. Thus philosophy justifies and continues

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common sense, as, for instance, the art of poetry justi­
fies and continues the natural rhythms of language.
It is also the province of philosophy to decide what
are the genuine certainties affirmed by common sense,
and what is their true significance ; a function which
common sense is incapable of performing, for the very
reason that it does not understand, or does not under­
stand clearly, the grounds of its knowledge. In this sense
philosophy controls common sense, as, for example, the
art of poetry controls the natural rhythms of language.
Nevertheless, common sense has the right and duty
to reject any philosophic teaching which denies a
truth of which it possesses natural certainty, as the
inferior has the right and duty to oppose a superior
who acts in a manner evidently unjust. For as soon
as a truth becomes known to us, by whatever channel,
it is a sin not to accept it. Common sense may there­
fore accidentally judge philosophy.
It is related of Diogenes that when Zeno the Eleatic
was arguing in his presence against the possibility of
motion, his sole reply was to get up and walk. Simi­
larly, when Descartes taught that motion is relative
or “ reciprocal,” so that it makes no difference whether
you say the moving object is moving towards the
goal or the goal towards the moving object, the
English philosopher Henry More retorted that when
a man runs towards a goal panting and tiring himself,1
he has no doubt which of the two, the moving object
or the goal, is in motion.
These protests of common sense based on the
evidence of the senses were perfectly justified. It
must, however, be added that they were insufficient
1 Letter of March 5, 1649.

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—not indeed to confute the respective theses of Zeno
and Descartes but to confute them as errors in philo­
sophy. That would have demanded a philosophic
refutation of the arguments adduced by these philo­
sophers, and explanations showing why and at what
point they went wrong.
It must be observed that though in itself and in
order to establish its demonstrations philosophy does
not depend upon the authority of common sense,
understood as the universal consent or common instinct
of mankind, nevertheless it is dependent upon it in a
certain sense (materially, or in respect of the subject),
in its origin as a human activity and in its development
in the mind of philosophers. From this point of view
philosophy may be compared to a building, and the
great pre-scientific conclusions of common sense (the
existence of God, the freedom of the will, etc.) to the
scaffolding which nature has erected beforehand.
Once the edifice has been completed it supports itself
on its rock-bed, the natural self-evidence of its first
principles, and has no need of scaffolding. But
without the scaffolding it could not have been built.
It is now evident how unreasonable that philosophy
is, which priding itself on its scientific knowledge of
things despises common sense a priori and on principle,
and cuts itself off from its natural convictions.
Descartes (who in other respects and in his very
conception of science concedes too much to common
sense) began this divorce, on the one hand, by
admitting as the only certain truths those scientifically
established, thus denying the intrinsic value of the
convictions of common sense, and on the other hand,
by professing as part of his system several doctrines
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incompatible with those convictions. His disciple
Malebranche, and above all the critical philosophers
of the Kantian school, as also certain modernist
philosophers, have carried this tendency to its extreme,
until for some of these philosophers it is sufficient that
a proposition should be acceptable to common sense
for it to be questioned or denied by science, which
would be contaminated by the “ credulity ” of the
common herd, unless it taught the contrary of what
mankind at large believes to be true.
Yet the greater the natural strength of a man’s
intelligence, the stronger should be his grasp of these
natural certainties. He therefore who professes to
condemn common sense shows not the strength but
the weakness of his understanding.
It is now obvious that in its attitude to common
sense, as in its solution of the majority of the great
philosophic problems, Thomism keeps the golden mean
between two opposing errors like a mountain summit
between two valleys.
Philosophy of Aristotle and St. Thomas
The convictions of common sense are valid, and
science is untrue to itself if it rejects them. But the
basis of philosophy is the natural witness of the intellect,
not the authority of common sense.
Scottish School
Not only are the convic­
tions of common sense
valid, but the authority of
common sense imposing
itself as a blind instinct on
the mind is the foundation
on which philosophy should
be based.

Rationalist, Critical, and
Modernist Schools
Not only is the authority
of common sense incapable
of furnishing the basis of
philosophy, but the con­
victions of common sense
are destitute of any specu­
lative value.

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SENSE

From all that has been said it is evident what an
important part the certainties of common sense play
as an introduction to philosophy. Those who are
beginning the study of philosophy and about to
acquaint themselves with the most recent problems,
and even perhaps the most misleading systems, ought
to repose an absolute trust in the convictions of
common sense of which they find their minds
already possessed, for they will help them to rise to
a higher and more perfect knowledge, conclusions
scientifically established.
Conclusion IV.—Philosophy is not based upon
the authority of common sense understood as
the universal consent or common instinct of
mankind ; it is nevertheless derived from common
sense considered as the understanding of selfevident first principles.
It is superior to common sense as the perfect
or “ scientific ” stage of knowledge is superior
to the imperfect or ordinary stage of the same
knowledge. Nevertheless philosophy may be
accidentally judged by common sense.
For the purposes of this present outline we need
only add that philosophy is not constructed a priori on
the basis of some particular fact selected by the
philosopher (Descartes’s cogito'), or principle arbitrarily
laid down by him (Spinoza’s substance, Fichte’s pure
ego, Schelling’s absolute, Hegel’s idea) whose conse­
quences he ingeniously develops. Its formal principles
are the first principles apprehended in the concept of
being, whose cogency consists wholly in their evidence
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for the intellect,1 and on the other hand its matter
is experience, and its facts12 the simplest and most
obvious facts—the starting-point from which it rises
to the causes and grounds which constitute the
ultimate explanation. Not a whimsy spun out of his
own brain, but the entire universe with its enormous
multitude and variety of data must be the philosopher’s
teacher.
And he must always bear in mind that, if philosophy
enables the human intellect to apprehend with absolute
certainty the highest and most profound realities of
the natural order, it cannot therefore claim to exhaust
those realities by making them known to the utmost
extent of their intelligibility. From this point of
view science does not destroy the mystery of things,
that in them which is still unknown and unfathomed,
but on the contrary recognises and delimits it ;3 even
what it knows it never knows completely. The wise
man knows all things, inasmuch as he knows them in
their ultimate causes, but he does not know, is infinitely
removed from knowing, everything about everything.
Ignorance, however, is not the same as error. It is
sufficient for the philosopher that he knows with
1 This is what the Positivists fail to see.
2 This is what the pure intellectualists—from Parmenides to Hegel—
who construct their metaphysics wholly a priori, have failed to grasp.
3 Aristotle (Metaph., i, 2) remarks that the occasional cause of
philosophy is rà 0av/j.á.£eiv, admiratio, by which he means wonder
mingled with dread, in other words awe, a wonder which knowledge
tends to remove. But we must be careful to understand his meaning
of the wonder which does not understand, not of the admiration, indeed
the awe, born of understanding. The wise man is astonished at
nothing because he knows the ultimate causes of all things, but he
admires far more than the ignorant man. Cf. De Part. Anim., i, 5, 645 a
16 : èv irâai rots pvaiKois ereart n Oa.v¡j.o.<TTÓv.

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certainty what it is his province to know
it is of the first importance for us to know.
is better not to know things which divert
from the highest knowledge, as Tacitus
nescire quaedam, magna pars sapientiae.
*
*
*
*

and what
Indeed, it
the mind
remarks :

*

We have considered the nature of philosophy ; it
remains to distinguish its departments. We shall
thus obtain a clear notion of its sphere, and at the same
time become acquainted with its principal problems.

HS

PART TWO
THE CLASSIFICATION OF PHILOSOPHY

K

I
THE MAIN DIVISIONS OF PHILOSOPHY

When a man undertakes a work, he begins by
testing his tool in various ways to learn the use he
can and should make of it.
The philosopher’s work is to acquire knowledge ;
his tool, reason. Therefore the philosopher before he
begins his work must examine reason to discover the
use he should make of it.
The study of reason as an instrument of acquiring
knowledge or means of discovering truth is called logic.
Logic is therefore, strictly speaking, not so much a
department of philosophy as a science or art, of which
philosophy (and indeed all the sciences) makes use,
and the introduction to philosophy. It is a propae­
deutic to science.1 The other sciences are dependent
upon logic inasmuch as it teaches the method of
procedure in the acquisition of knowledge, and we are
obliged to possess the means or tools of knowledge
before we can acquire knowledge itself.
It is thus evident that the study of philosophy must
1 “ Res autem de quibus est logica, non quaeruntur ad cognoscendum propter
seipsas, sed ut adminiculum quoddam ad alias scientias. Et ideo logica non
continetur sub philosophia speculativa quasi principalis pars, sed quasi quoddam
reductum ad eam, prout ministrat speculationi sua instrumenta, scilicet
syllogismos et definitiones, et alia hujusmodi, quibus in speculativis scientiis
indigemus. Unde et secundum Boethium in Comment, sup. Porphyrium,
non tam est scientia quam scientiae instrumentum.” St. Thomas, Sup.
Boet, de Trin., q. 5, a. 1, ad 2. It is therefore only reductively that
logic belongs to theoretical philosophy.

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from the very nature of things begin with logic,
although on account of its difficulty and extremely
abstract character logic usually repels rather than
attracts beginners.1 A few of the moderns rebel
against this order of study, and maintain that logic
should be studied only in the course of learning the
other branches of philosophy, or after they have been
learned. But this is like arguing that the surgeon
should only study anatomy by the practice or after the
practice of his art upon the sick. It is absurd, Aristotle
remarks, to study at the same time a science and its
conditions or method of procedure, cctokov agoc
ÇvjTSÏV ¿7il<7T7)g7)V X0CL TpOTCOV S7tt<TT4(Z7)q’.i

When by the study of logic he has made himself
master of his tool, the philosopher can set to work.
What that work is we know already : to acquire a
knowledge of things by their first principles.
If, however, we consider the aim of learning, there
are two distinct types of knowledge. We can, for
example, make use of our eyes simply in order to see
1 Cf. St. Thomas, Sup. Boet. de Trin., q. 6, a. I, ad 3. “Dicendum quod
in addiscendo incipimus ab eo, quod est magisfacile, nisi necessitas aliud requirat.
Quandoque enim necesse est in addiscendo non incipere ab eo quod estfacilius, sed
ab eo a cujus cognitione cognitio sequentium dependet. Et hac positione oportet
in addiscendo incipere a logica, non quia ipsa sit facilior scientiis ceteris ; habet
enim maximam difficultatem, cum sit de secundo intellectis ; sed quia aliae
scientiae ab ipsa dependent, in quantum ipsa docet modum procedendi in omnibus
scientiis. Oportet enim primum scire modum scientiae quam scientiam ipsam, ut
dicitur II. Metaph.
2 Metaph., ii, 995 a 12. St. Thomas, In II Metaph., 1. 5. “ Quia
enim diversi secundum diversos modos veritatem inquirunt, ideo oportet quod homo
instruatur per quem modum in singulis scientiis sint recipienda ea quae dicuntur.
Et quia non est facile, quod homo simul duo capiat, sed dum ad duo attendit,
neutrum capere potest : absurdum est, quod homo simul quaerat scientiam et
modum qui convenit scientiae. Et propter hoc debet prius addiscere logicam quam
alias scientias, quia logica tradit communem modum procedendi in omnibus
scientiis.”

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and enjoy the sight of things, and we can also make
use of them for the practical purposes of life.
In the same way we can employ our reason
scientifically, solely for the pleasure of knowledge.
The sciences thus acquired exist solely for the sake
of knowledge (the theoretical sciences). And if there
be a theoretical science which seeks to account for
things by their first principles, its object will be that
which is the first principle in the theoretical order,
namely, the first causes of everything which exist (that
is to say, the first causes naturally knowable). That
science is theoretical philosophy. We can, on the other
hand, employ our reason scientifically for our profit
and the improvement of our life ; the sciences thus
acquired exist to procure by some kind of activity the good
of man (the practical sciences). And if there be a
practical science which seeks to regulate human acts
by first principles, its object will be that which is the
first principle in the practical order, namely, the absolute
good of man (the absolute good naturally knowable).1
Such a science is practical philosophy—otherwise termed
moral science or ethics.a
There are, indeed, other practical sciences besides
ethics ; for example, medicine, which seeks to procure
the health of man. But the object of these sciences
is not good, pure and simple (the sovereign good),
but some particular human good. They do not,1
2
1 That is to say, the sovereign good of man as it would be, if his end
were simply natural happiness. See below, pp. 265-267.
2 Observe that this division of philosophy into theoretical and
practical relates to the end, the aim, not to the object itself of the science,
which as such is always necessarily theoretical. Therefore it does not
enter into the specification in the strict sense of the philosophic sciences.
See below, p. 271.

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therefore, refer in the practical order to which they
belong to the first principle of action, and for that
reason are not philosophies. Ethics, or moral
science, is thus the only practical science which
deserves the name of philosophy.1
We must bear in mind that although the object of
ethics is to procure a good which is not solely a good
of the intellect, that is to say, does not consist in know­
ledge alone, its rule of truth is that which is, and it
proceeds by way of demonstration, resolving conclusions
into their premisses. In other words it is practical
in virtue of its object (to know in order to procure the
good of man in the ordering of his acts), but as science
in the strict sense it is theoretical knowledge.12
We must further remark that the practical sciences
are obviously subordinate to the theoretical, (i) as
presupposing (if not in the order of their origin in
1 It may be added that of the practical sciences, only one, ethics, is
in fact vere et proprie scientia, that is to say, proceeds by way of demon­
stration, in a necessary matter, and imparts a truth, which consists in
knowing things in conformity with what is, and not in properly directing
a contingent action. The other practical sciences (medicine, architec­
ture, strategy, etc.) are arts, not sciences in the strict sense. (Cf. John
of St. Thomas, Cursus Philos., i, Log. ii, q. I, a. 5).
But though ethics is in the strict sense a science, it is for that very
reason only in an indirect sense practical : for its procedure consists
in providing knowledge (speculabiliter) not in producing action (operabiliter), and though it certainly supplies rules immediately applicable
to concrete cases, the right application and good use of these rules in
practice is the effect not of ethics but of the virtue of prudence.
On the other hand, as we shall see later, the philosophy of art is also,
in a sense, a practical philosophy. But it is very far from being a
practical science, even like ethics in the indirect sense, for it treats only
of principles and is unable to descend to the rules immediately applicable
to the concrete work to be executed.
2 Hence even practical philosophy is a theoretical wisdom which
proceeds by way of knowledge (see above, p. 102).

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time, at least in the nature of things) the truths proved
by these sciences, which they apply for the benefit
of man—for example, medicine, as the science of
healing, presupposes anatomy ; (ii) as sciences inferior
in dignity to the theoretical sciences. For the latter
are studied for their own sake, and are therefore good
in themselves, whereas the practical sciences are
studied for the good or utility of man, and are therefore
good only in relation to that good or utility. It
follows that philosophy in the strictest sense is
theoretical philosophy (especially the first philosophy
or metaphysics}, logic being the science introductory
to it, and ethics the science detached from it to treat
specially of that which concerns the good of man.

We are now in a position to define more exactly
the object of these three main divisions of philosophy.
A science which seeks to procure man’s sovereign
good must before all else treat of those things which
are the indispensable conditions of its attainment.
But these are the actions which man performs in the
free exercise of his faculties ; in other words, human
acts as such. We may therefore say that human
acts are the formal object (subject-matter) of moral
philosophy.
A science whose aim is to know things by their first
causes must treat primarily of that in things which
depends immediately upon those causes. But that
in things which depends immediately upon the first
or highest causes is that which is most essential in
them, their being, and that which is the most widely,
indeed universally, distributed, being, which everything
whatsoever possesses. We therefore conclude that the

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formal object of theoretical philosophy is the being
of things.
Now theoretical philosophy studies the being of
things in different fashions and from higher or lower
points of view (degrees of abstraction). It may study
the being of things with their sensible properties {ens
mobile}, or the being of things with the sole properties
of quantity {ens quantum), or the being of things with
the sole properties of being (being qua being, ens in
quantum ens). Hence arise the three principal divisions
of theoretical philosophy (see below, Chs. Ill & IV).
Finally, a science which studies reason as the tool
for the attainment of truth must treat before all else
of that which we handle or manipulate when we
reason. But that which we handle or manipulate when
we reason is the things themselves. For example, when
we affirm that man is superior to the other animals because
he possesses intellect, it is indeed the thing itself, man,
which we hold in our mind and to which we join or
attribute those other things, intellect and superiority.
But the man that we thus handle in our mind is
obviously not the man as he exists, or can exist in
reality ; there is no question of seizing some man
who passes in the street to stick an attribute on to his
back. That our mind may work on them, things
possess in the mind a manner of being which they do
not and cannot possess in reality. They exist there
so far as they are known. Predicated one of another
divided, reunited, linked together according to the
necessities of knowledge, they lead there a distinct
life, with its own laws. It is this life and its laws,
the order to which things must submit so far as they
are objects of knowledge, if they are to guide the mind
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to truth, that logic primarily studies, and since it is
concerned with something which exists and can exist
only in the mind or with what philosophers term an
ens rationis, a conceptual being, we may say that the
formal object of logic is that conceptual being,
ens rationis (the order which should prevail among
conceptual objects) which directs the mind to truth.
As opposed to conceptual being, the ens rationis, which
can exist only in the mind—for example, the genus
animal or the species man (the genus animal comprises
mankind and the brutes, man is the species of Peter)—we
term real being, ens reale, that which exists or can exist
in reality—for example, animals, man, human nature
(all animals are mortal, human nature is fallible').
Conclusion V.—Philosophy is divided into three
principal parts : (i) logic, which is the introduc­
tion to philosophy in the strict sense, and which
studies the conceptual being (ens rationis) which
directs the mind to truth ;
(ii) theoretical
philosophy or simply philosophy, which studies the
being of things (real being, ens reale) ; (iii) practical
philosophy or ethics, which studies human acts.

I53

II
LOGIC

Logic studies reason as the tool of knowledge. To
study any complicated machine, a reaper for instance,
we must begin by making it work in the void, while we
learn how to use it correctly and without damaging it.
In the same way we must first of all learn how to use
reason correctly, that is to say, in conformity with the
nature of ratiocination, and without damaging it.
Hence arises our first problem : What are the rules
which we must obey in order to reason correctly?
We should next study our reaper no longer in the
void, but as applied to the actual material with which
it was designed to deal, learning how to use it, not
only correctly, but profitably and efficiently. In the same
way we must study reasoning as applied to facts,
asking ourselves under what conditions reasoning is
not only correct but also true and conclusive, and
productive of knowledge. It is in this department of
logic that we study the methods employed by the
different sciences. But before this a far graver
problem will arise and demand solution.

It is by our ideas that things are presented to the
mind, so that we can reason about them and acquire
knowledge.
Everybody knows by experience what an idea is.
It is sufficient for a man to reflect on what is in

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his mind, when he makes a judgment of any kind.
For instance, philosophers have made many mistakes;
philosophers, mistakes, have made, many—all these are
present in the mind as so many ideas. Nevertheless
to clear up any possible obscurity, we will try to
describe what everybody means by the word. We
will, for instance, define ideas as images or interior
reproductions of things, by which the latter are pre­
sented to us in such a way that we can reason about
them (and thus acquire knowledge).
No doubt the words we employ express our ideas.
But they bring with them something besides. If, for
example, I pronounce the word angel, I have in my
consciousness two images of the being in question.
In the first place an idea, in virtue of which, strictly
speaking, I know that particular being (the idea of a
pure spirit), but in addition a sensible representation
(the image of some figure more or less nebulous and
winged) which possesses no likeness whatever to the
being in question, for a purely spiritual being is
invisible.
If, again, I pronounce the word square I have in
my consciousness the idea of the square, by means
of which I can reason about the thing concerned (the
idea of a rectangular polygon of four equal sides') and at
the same time a sensible representation—which in this
case adequately represents the thing in question—a
particular figure which I imagine drawn in chalk on
the blackboard. The idea and the representation are
quite distinct, as is shown by the fact that I can vary
the latter in a host of different ways (the imaginary
drawing can be larger or smaller, white, red, yellow,
etc.) without any variation of the former. Moreover,
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- if I were to pronounce, for example, the word myriagon
instead of square, I should possess as definite and as
clear an idea of it as I had of the square (the idea of
a polygon of ten thousand sides'), whereas the only sensible
representation I could form of it would be extremely
vague and confused.
It is evident that if the sensible representations
assist me to reason, they are not the instrument with
which I reason to acquire a knowledge of things.
For I can reason as accurately about the angel or the
myriagon as I can about the square. And my reasoning
is in no way dependent on the thousand alterations
I can make in my sensible representations of an angel,
myriagon, or square.
From this we conclude that things are presented to
our consciousness in two different fashions, either by an
idea or by a sensible representation.
By the first we think {intelligimus) the thing, by the
second we imagine it. The representation is simply a
species of phantom, an image of what we have pre­
viously seen, heard, touched, etc., in short, of what
has been originally made known to us by a sensation.
Formerly called a phantasm, it is now called simply an
image. In future, then, we shall reserve to denote
it the term image, whose meaning we accordingly
restrict. (But we must no longer use the same word
to denote an idea.) We conclude, therefore, that—

Conclusion VI.—Ideas are the internal likenesses
of things by which the latter are presented in such
a way that we can reason about them (and thus
acquire knowledge) ; images are the internal
likenesses of things by which the latter are pre156

LOGIC

sented to us as our sensations have first made them
known to us. Words directly signify ideas, at the
same time evoking images.
If now we compare objects as they are presented
by ideas and as they are presented by sensations or
images, we see at once that they are distinguished
by a character of the very first importance. If, for
example, I call up before my mind the image of a
man, I see present in my imagination with outlines
more or less vague and more or less simplified some
particular man. He is fair or dark, tall or short,
white or black, etc. But if I form the idea of man,
as, for instance, when I state the proposition man is
superior to the irrational animals, or whites and blacks are
alike men, that idea does not bring before me any
man in particular. It leaves out of account all the
individual characteristics which distinguish one man
from another ; in the language of philosophy it
abstracts from them.
This is proved by the fact that while remaining
absolutely the same and without need of any modifica­
tion whatsoever, it can be applied to the most dis­
similar individuals ; Sancho Panza is just as much a
man as Don Quixote. Moreover, when we cast our
mind over the different sciences, that is to say, the
different systems of ideas by which we know reality,
we find that none of them is concerned with the
individual as such. Chemistry, for instance, only
studies in chlorine or nitrogen what is common to all
the individual molecules of chlorine or nitrogen.
And this must necessarily be the case. The individual
as such explains nothing (for, since it represents only

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itself, it obviously cannot account for anything else).1
Again, we have only to take any idea whatsoever and
fix our attention on what it presents to us, comparing
it with the images which form and dissolve around it,
to perceive at once the abstract nature of the idea.
In the transition from the image to the idea whatever
is individual evaporates, so to speak, slips between
our fingers, and vanishes. Take, for example, the
idea of weapon which I employ when I state that
man is the only animal obliged to manufacture its weapons.
As I pronounced the word weapons, I was no doubt
conscious of a halo, so to speak, of fluctuating images
surrounding the idea thus expressed, to any of which
I can at pleasure give a more definite shape, a javelin
very shadowy no doubt, a flint axe, a cross-bow, a
gun. . . . But of the individual characteristics of the
particular javelin, axe, bow, or gun as they appear
in my imagination with their distinctive form, colour,
and dimensions, nothing whatever remains in my idea
of weapon. Everything of the sort has disappeared.
Though what I apprehend by the idea is certainly
some thing, that some thing is of an entirely different
order (immaterial), it is simply a certain determination
of being, a certain nature, an instrument of attack or
defence ; and that is devoid of any individual character.
That is to say, objects as presented to us by our
sensations and images are presented in a state which is
individual, or in technical language singular. On the
contrary, objects as presented to us by our ideas, by
the internal likenesses which enable us to reason about
them, are presented in a state which is non-individual,
abstract, or in technical language universal.
1 Cf. T. Richard, op. cit., p. 21.

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We call universal that which is the same in a multi­
tude of individuals, one in many, unum in multis.} We
shall therefore hold as an established truth that—

Conclusion VII.—Our sensations and images
present to us directly or by themselves the indi­
vidual, our ideas directly and by themselves the
universal.
But the question at once arises : Since real objects
are individual or singular, how can the knowledge
we obtain by means of our ideas be true, since our
ideas directly present only the universal ?
This problem, which will compel us to investigate
carefully in what exactly consists the universality of
that which our ideas present, is, not indeed in itself,
but at any rate for us men, the first and most im­
portant of philosophic problems.1 For it is concerned
with the nature of the intellect itself and of our ideas,
that is to say, with the instrument by which all our
knowledge is obtained ; and the solution propounded
by different philosophers dominates their entire
system.
From this point of view, and taking no account of
many differences of secondary importance, we may
classify philosophers in three great schools :
(a) The nominalist school, for which universals have
1 Does the problem of universals belong to logic, psychology, or
metaphysics (criticism or epistemology) ? To all three, in fact,
according as it is studied from three different standpoints. We may
inquire what constitutes the nature of a universal (standpoint of the
formal cause"), or the manner in which a universal is formed in the mind
(standpoint of the efficient cause), or the epistemological value of the
universal (standpoint of the final cause).

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no existence except as names or ideas with which
nothing in reality corresponds ; for instance, there is
nothing in the reality of human nature which is equally
present in Peter, Paul, and John. This position amounts
to sheer negation of the possibility of intellectual
knowledge, and reduces science to a figment of the
mind. The most typical representatives of this school
are, in antiquity the sophists and the sceptics, in modern
times the leading English philosophers, William of
Occam in the fourteenth century, Hobbes and Locke
in the seventeenth, Berkeley and Hume in the eigh­
teenth, John Stuart Mill and Spencer in the nine­
teenth. It may be added that the majority of modern
philosophers (that is to say, of those who ignore or
oppose the scholastic tradition) are more or less
deeply, and more or less consciously, imbued with
nominalism.
(¿) The realist school (“ absolute realism ”) for which
the universal as such, the universal taken separately,
as it exists in thought, constitutes the reality of things.
This position reduces sense-knowledge to mere illusion.
That which is real is, for example, a human nature
existing in itself and separately outside the mind, a man in
himself (Platonism), or a universal being existing as such
outside the mind and regarded as the sole and unique substance
(doctrine of Parmenides, Vedantism). The systems of
certain modern philosophers (Spinoza, Hegel) approxi­
mate more or less closely to realism.1
(c) The school which is usually called that of
1 It must be borne in mind that realism understood in this sense,
far from being incompatible with idealism, is essentially an idealist
doctrine. For realism of this type regards as the reality of things
that which is distinctive of our ideas as such. Plato is thus at once
the most typical representative both of idealism and absolute realism.

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moderate realism. (Its doctrine, however, is in the most
strict sense original, and keeps the just mean between
realism and nominalism, not by watering down or
modifying absolute realism, but by a view of things
which transcends the opposing errors.) This school,
distinguishing between the thing itself and its mode
of existence, the condition in which it is presented,
teaches that a thing exists in the mind as a universal,
in reality as an individual. Therefore that which we
apprehend by our ideas as a universal does indeed
really exist, but only in the objects themselves and
therefore individuated—not as a universal. For
example, the human nature found alike in Peter, Paul,
and John really exists, but it has no existence outside the
mind, except in these individual subjects and as identical
with them ; it has no separate existence, does not exist in
itself. This moderate realism is the doctrine of
Aristotle and St. Thomas.
Philosophy of Aristotle
and St. Thomas (Moderate Realism}
That which our ideas
That which our ideas
present to us as a universal present to us as a universal
does not exist outside the exists outside the mind
individuated.
mind as a universal.

Nominalism
That which our ideas
present to us as a universal
has no real existence what­
soever.

Realism
That which our ideas
present to us as a universal
really exists as a universal.

It is impossible to over-emphasise the importance
of the problem of universals. It is for want of atten­
tion to it that so many philosophers and scientists of
modern times cling to the naive belief that science
L
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must be a copy pure and simple, a tracing of the
individual reality ; serve up the stock arguments
of ignorance against abstraction, the essential pre­
condition of all human knowledge ; and when treating
of the principles of the sciences, especially of mathe­
matics, spin elaborate theories, devoid of solid founda­
tion, whose sole result is to render knowledge totally
impossible.

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THE PHILOSOPHY OF MATHEMATICS
THE PHILOSOPHY OF NATURE

distinctive object of theoretical philosophy is
the being of things. The things which are immedi­
ately observed are corporeal things, bodies. But the
term body may be taken in two distinct senses. It
may mean a mathematical body, or a natural or physical
body. A mathematical body is simply that which
possesses three-dimensional extension, breadth, length,
and height. A natural or physical body is that
which is perceived by the senses as possessing certain
active and passive properties.

The

THE PHILOSOPHY OF MATHEMATICS

If the philosophy of mathematics studies the being of
bodies in the first sense of the term body, it is obvious
that the first problem it must consider is in what does
the primary object of mathematics consist ; in other
words, what is the nature of quantity, extension, and
number ? 1
1 Questions relating to the philosophy of mathematics are usually
treated in natural philosophy or in metaphysics. We believe, however,
that if classification is to be scientific, we are obliged to maintain in
what is now known as philosophy (scientific knowledge of things by
their first causes) the fundamental division of the sciences (the whole
group of which constituted for the ancients theoretical philosophy)
into three parts : physica, mathematica, metaphysica, corresponding to

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The enormous progress made by modern mathe­
matics has rendered more indispensable than ever
before the philosophic study of the first principles of
the mathematical sciences, which alone can provide
a rational account of the true nature of mathematical
abstraction and the mental objects which it considers,
the properties and mutual relationships of the con­
tinuous and the discontinuous, the real meaning of surds
and transfinite numbers, the infinitesimal, non-Euclidean
space, etc., and finally of the validity of mathematical
transcripts of physical reality, and of such hypotheses,
for example, as the theory of relativity.
THE PHILOSOPHY OF NATURE 1

Since the philosophy of sensible nature studies the being
of bodies in the second sense of the term body, it
the three grades of abstraction (seep. 152). Cf. Aristotle, Metaph., vi, 1,
1026 a 18. t/kîs
elev </>i\o!To<l>lai OeapyriKai, p.aOi¡p.ariKh, <t>wrurfi,
OeoXoyiKh.
It is true, as we shall see later, that the philosophy of mathematics,
for the very reason that it studies the essence of quantity and is thus
at least reductively metaphysical, transcends the strict sphere of the
mathematical sciences and is specifically distinct from them. This,
however, does not alter the fact that it is concerned with the second
degree of abstraction and must therefore be studied as a separate
branch of philosophy.
1 In the logical order of the sciences, the natural sciences which
correspond to the first degree of abstraction (see p. 152) precede the
mathematical sciences, which correspond to the second, so that in
accordance with this order we should be obliged to divide theoretical
philosophy into (i) The philosophy of nature (corresponding to the first
degree of abstraction), (ii) The philosophy of mathematics (corresponding
to the second degree), (iii) metaphysics (corresponding to the third
degree).
Nevertheless the philosophy of mathematics should precede natural
philosophy for two reasons.
On the one hand, truths of the mathematical order are easier to

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must deal with a large number of problems. We can,
however, pick out the most important of these for
mention here.
The most universal and obvious characteristic of
the corporeal world, which is involved in every
physical event, is change. Philosophers, in whose
vocabulary change of every description is termed
motion, must therefore inquire what motion is.
It is at once obvious that if motion exists, something
must be moved, namely, bodies. Further, certain
changes seem to affect the very substance of bodies ;
as, for instance, when the chemical combination of
hydrogen and oxygen produces a new body, water.
How is this possible ? We are compelled to ask
what corporeal substance is.
(a) The mechanists—whether in their doctrine of
the human soul they are materialists (Democritus,
Epicurus, Lucretius, among the ancients, Hobbes in
the seventeenth century, etc.) or spiritualists like
apprehend than truths of the natural order, which presuppose
experience. For this reason children should be taught the elements
of mathematics before the natural sciences, the study of which requires
a more advanced age. (Cf. Aristotle, JV/c. Eth., vi ; St. Thomas,
Sup. Boet. de Trin., q. 5, a. I, ad 3.)
We should therefore follow the same order in philosophy and lead the
mind up to the study of natural philosophy by the study of the
philosophy of mathematics.
On the other hand, and this is the more important consideration,
natural philosophy with the last and highest of its sub-divisions,
namely psychology, touches the frontier of metaphysics. It would be
a breach of continuity to insert the philosophy of mathematics between
natural philosophy and metaphysics.
In the seventeenth century Sylvester Maurus maintained—and in
so doing was faithful to the Aristotelian tradition—that the natural
order of study is as follows : (i) logic, (ii) mathematics, (iii) physics,
(iv) metaphysics. (Quaest. philos., i, q. vii.)

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Descartes—reduce corporeal substance to matter, which
in turn they confuse with quantity or geometrical
extension. They can therefore admit no essential
or specific difference among bodies, which are all
modifications of one single substance. Moreover, the
physical universe is for them devoid of quality and
energy, since space and local motion alone are real,
and the union of matter and spirit in a being such as
man becomes absolutely unintelligible.
(¿) Another school (dynamism) tends on the contrary
to get rid of matter as a constituent of bodies. It
culminates in the system of Leibniz, who reduced
corporeal substance to units of a spiritual character
(monads') analogous to souls. For Leibniz extension,
indeed sensible reality as a whole, is nothing more
than an appearance or a symbol, and the corporeal
world as such is absorbed in the spiritual. The
dynamism of Boscovich (eighteenth century), who
reduced corporeal substance to points offorce, and the
modern physical theory which claims to explain
everything in the physical universe as manifestations
of one sole reality, energy (of which, however, its ex­
ponents fail to give a philosophic definition), may be
regarded as degradations and materialisations of
Leibniz’s doctrine.
(c) The Aristotelian philosophy recognises in
corporeal substance two substantial principles :
(i) matter (first matter, materia prima), which, however,
in no way represents, as in the conception of the
mechanists, the imaginable notion of extension, but
the idea of matter (that of which something else is
made) in its utmost purity—it is what Plato called a
sort of non-entity, simply that of which things are
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made, which in itself is nothing actual, a principle
wholly indeterminate, incapable of separate existence,
but capable of existing in conjunction with something
else (the form) ; (ii) an active principle, which is
so to speak, the living idea or soul of the thing, and
which determines the purely passive first matter,
somewhat as the form imposed upon it by the sculptor
determines the clay, constituting with it one single
thing actually existent, one single corporeal substance,
which owes to it both that it is this or that kind of
thing, that is to say, its specific nature, and its existence,
somewhat as the form imposed by the sculptor makes
a statue what it is. On account of this analogy with
the external form of a statue (its accidental form)
Aristotle gave the name ofform {substantial form), which
must be understood in a sense altogether special and
technical, to this internal principle of which we are
speaking, which determines the very being of corporeal
substance.
The Aristotelian doctrine, which regards a body as
a compound of matter (uXt¡) and form (ptopcp-Zj), is known
as hylomorphism. It accepts the reality, on the one hand,
of matter, the corporeal world, and extension,1 on
the other of physical qualities,1
2 also a distinction of
nature or essence between the bodies which we regard
as belonging to different species. It reveals the
presence, even in inanimate bodies and living things
devoid of reason, of a substantial principle, immaterial
in its nature, which, however, differs from spirits in
1 Extension of quantity is not, as the mechanists hold, the substance
of bodies, but their first accident.
2 Qualities are also accidents of corporeal substance. (See below,
pp. 217-332 (substance and accident).)

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the strict sense, in its incapacity to exist apart from
matter. And it renders intelligible the union in
the human being of matter and a spiritual soul which
is the form of the human body, but differs from the
other substantial forms inasmuch as it can exist apart
from matter.
Philosophy of Aristotle and St. Thomas (Hylomorphism)
Every corporeal substance is a compound of two
substantial and complementary parts, one passive and
in itself wholly indeterminate (matter), the other active
and the principle of determination (form).
Mechanism
Corporeal substance is
regarded as something
simple, a matter itself
identified with geometrical
extension.

Dynamism
Corporeal substance is
explained either as units
belonging to the category
of pure forms and spirits
(Leibnizian monadism) or
as a manifestation of force
or energy.

We have now to consider a class of bodies which
possess a peculiar interest for us, and seem to be superior
to all the others. They are living bodies, from the
lowliest micro-organism to the human organism.
The property which distinguishes them from all other
bodies is self-movement. On that account common sense
recognises in them a soul or principle of life, irreducible
to any combination of physico-chemical factors or
elements. If this is indeed the case, we must inquire
whether there are not different kinds of soul, whether
vegetables and animals possess a soul, etc. On the
other hand certain philosophers (known by the
general appellation of mechanists) claim that science
will one day explain all the phenomena of life by
the forces of lifeless matter, that is to say, that the living
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organism is simply a very complicated physico­
chemical machine. This involves a problem of the
first importance. What is life ? What are the first
principles which constitute the living organism ?
But of all living things which possess a body the
highest is man. Man is as it were a world apart,
for the study of which we are in a peculiarly favourable
position, because we know him from within by what is
called self-consciousness. His most distinctive charac­
teristic is the possession of intelligence or reason. If,
however, intelligence is indeed something wholly
immaterial, it follows that the science which studies
man, though a branch of natural philosophy which
treats of moving or sensible being, is in a sense
intermediate between this department of philosophy
and metaphysics which treats of the wholly immaterial.1
If it is the possession of intelligence or reason which
makes man man, the problems which relate to his
intellectual activity must, it would seem, dominate
the entire science of man.2 And in fact the
1 The science of man occupies therefore a singular position (due to
the very nature of its object) astride two distinct sciences, natural
philosophy and metaphysics. It is for this reason that all questions
involving the intellect and the strictly spiritual portion of psychology
display in the case of man such extreme complexity and are, so to
speak, overshadowed by matter. It is not surprising, therefore, that
when the Thomists wished to investigate these questions in their purity
they studied not man but the angels. Hence the extreme importance
of the treatise De Angelis, not for theology alone, but also for philosophy
and metaphysics.
2 Observe that psychology as understood by the moderns does not
correspond exactly to the ancients’ treatment of the soul. Aristotle’s
repi ÿvxw. De Anima, studies not only the human soul, but also the soul
in general as the principle of life, whether vegetative, sensitive, or
intellectual. Such a treatise therefore belongs to what we now call
biology as well as to psychology.

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fundamental problem of psychology is that of the origin
of ideas : how we are to explain the presence in us of
the ideas which enable us to reason about things
and which present things to us as universals.
At this point we have been brought back by a
different approach to the problem of universals which
we have lately considered. We then noted that what
our ideas immediately present to us is something
non-individual or universal. We have now to ask
how this knowledge of the universal is acquired by
our minds.
We saw above that things as they are known by
the senses and the imagination are presented as
individuals. It is this particular man that I see, with
this particular appearance actually impressing itself
on my retina and distinguishing him from the other
man I see beside him. Sense-knowledge is thus
knowledge of the individual alone. The object as
object of sensation or the object reproduced by an
image is the object apprehended in its individuality.
Since, therefore, what we know immediately by our
ideas is not individual, the reason must be that our
ideas are in fact extracted by us from our sensations and
images, but in such a fashion that there enters into
them nothing whatsoever of the object as it exists
as an object of sensation or reproduced by an image (that is
to say, as we shall see later, as the object of a know­
ledge steeped in materiality). Arising from images,
but of a higher order than the image, and apprehending
nothing of the object as reproduced by the image, our
ideas must necessarily be unable to give us any know­
ledge of the object in its individuality.
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Moreover, we could not possibly derive our ideas
from things, except by way of our senses, which are
in immediate contact with things. And we have
only to observe the mental development of a child to
be convinced that all our knowledge begins with the
senses. Therefore intellectual knowledge (knowledge
by means of ideas) must undoubtedly be derived from
sense-knowledge.
On the other hand, since everything apprehended
by sensations and images is characterised by individu­
ality, our ideas must be extracted from images in such
a way that nothing of the image, as such, enters into
the idea.
But how is this process of extraction conceivable ?
If nothing whatever of the object as it is reproduced
by the image enters into the object as it is apprehended
by the idea, it is obvious that the idea is not the result
of any combination or distillation of sensations or
images. We are therefore compelled to postulate an
agent of a higher order, the voüç tcoititixó?, as the
Peripatetics termed it, the intellectus agens—a kind of
intellectual light (we may perhaps compare it to
X-rays) which, when applied to the object presented
to us by the image, draws out of it for our understanding
something already contained in it but hidden, which
the image by itself could never reveal. The some­
thing thus extracted and liberated from that which
constitutes the individuality of the object (because
it is liberated from that which constitutes the materi­
ality of sense-knowledge) is the form or intelligible
likeness of the object, which is, so to speak, imprinted
on the intellect to determine it to know, by making
it produce within itself by a vital reaction the idea
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in which it apprehends the object as a universal ; for
example, the idea of man or living being, of Aryan or
Semite.
We must, however, remember that what our ideas
present thus as a universal is in itself (abstracting
from its existence either in things or in the mind)
neither individual nor universal, being purely and
simply that which the thing is.1
We must also bear in mind that, if our intellect
does not directly know the individual as such, it
knows it indirectly. For, at the very moment when
it thinks of an object by means of an idea, it turns to
the images from which the idea has been drawn,
which present the thing as an individual. And by
thus reflecting on the images it apprehends, though
indirectly and in a manner wholly superficial and
totally inexpressible, the individuality of the thing.

Conclusion VIII.—Our ideas are extracted {ab­
stracted'} from the sensible datum by the activity
of a special faculty (the intellectus agens or active
intellect} which entirely transcends the sensible
order and is, as it were, the light of our under­
standing.
Philosophers term abstraction the operation by which
we thus extract our ideas from the store of images
accumulated by sense experience, ideas which repre­
sent that which the thing is, abstracting from its
individuality.
Here we may add that abstraction admits of lesser
and greater degrees. For instance, though the idea
1 I.e. the nature, essence, or quiddity, of the object. See pp. 201, 206.

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of horse is, like every idea, abstract, when we think of
horse we can at the same time see or imagine horses,
and thus know in the sensible order what we know
at the same time by means of our idea in the intelligible
order. If, on the other hand, we think of angel or
spirit, the sole function of the more or less vague images
which accompany the thought is, as we have already
observed, to assist the intellect to function. In their
own order they have no value as knowledge, for they
tell us nothing. We can neither see nor imagine an
angel or a spirit ; in this case, therefore, we cannot
at the same time know by our senses the thing we
know by our intellect.
It is important to bear in mind that the things
with which philosophy is primarily concerned belong
to this second category. They cannot be known
either by the senses or the imagination, but solely by
the intellect.
It is to this higher degree of abstraction that the
study of philosophy owes its special difficulty. Be­
ginners are often perplexed when they suddenly
exchange the literary studies on which they have been
engaged hitherto, studies in which the imagination
was employed equally with the intellect, for an exercise
wholly intellectual. But this difficulty will soon pass,
if they will not try to represent by the imagination
objects of pure thought which are entirely unimagin­
able, such, for instance, as essence, substance, accident,
potentiality, and act ; a chimerical attempt, which will
only cause needless headaches and effectually prevent
them from understanding anything of philosophy.
If abstraction is indeed such an operation as we
have described, it follows in the first place that man

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is endowed with a spiritual soul, the first principle
of this function (for its result, our ideas, is incommensur­
able with sensations and images and of a purely
immaterial order) ; and on the other hand, that it is
of the very nature of this spiritual soul to be united
to a body (for our ideas cannot be formed except by
means of sensations and images, which in turn neces­
sarily suppose bodily organs). We thus perceive how
the problem of abstraction, or the origin of ideas, is
bound up with another fundamental problem of
psychology, which concerns the very essence of man :
in what does the human being consist? Does man
possess a spiritual soul, wholly different from that of
the beasts ? And if so what is the relationship between
this soul and the human body ?

On the problem of the origin of ideas philosophers
may be divided roughly into three main groups :
(a) The sensualists, who hold that ideas are derived
from the senses, but reduce ideas to sensations, (ó) The
partisans of innate ideas,1 who recognise the essential
distinction between ideas and sensations or images,
but deny that we extract our ideas from the sense
datum, (c) The school of Aristotle and St. Thomas,
which holds that our ideas differ essentially from
sensations and images, but that they are extracted
1 We may so term this second group in default of a more suitable title,
but only if we considerably widen its meaning. For in this class of
philosophers we must include not only those who teach that our ideas
exist in our minds from birth in the same way as our soul exists (the
doctrine of innate ideas in the strict sense), but those who hold that
they are immediately implanted in us by God or are seen by us in God
(Berkeley, Malebranche), or are the arbitrary product of our mind
imposing its laws on things (Kant).

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from them by the operation of the spiritual light in us
(vouç tcoi.7)tixôç3 intellectus agens).
The principal representatives of sensualism are
Locke (seventeenth century) and John Stuart Mill
(nineteenth century) in England, and Condillac
(eighteenth century) in France. The sensualists are,
as a rule, also nominalists, but the converse does not
hold, and many philosophers whom we class here
among the defenders of innate ideas betray, in modern
times at least, the influence of nominalism. In the
second class (the defenders of innate ideas) we must
reckon Plato among the ancients, Descartes (seven­
teenth century) and Leibniz (seventeenth to eighteenth
century) among the moderns. Though their explana­
tions differ, all these hold that our ideas are innate.
Kant (end of eighteenth century) also belongs to this
group, though for him what is innate is not our ideas,
but the categories, rules, or forms in accordance with
which our mind manufactures the objects of knowledge.
Philosophy of Aristotle and St. Thomas
Our ideas are derived
Our ideas are essentially
from the senses (and there­ different from sensations
fore from things) but by and images, but are ab­
the operation of a spiritual stracted from them by the
faculty, and are essentially operation of a spiritual
different from sensations faculty.
and images.
Sensualism
Our ideas are derived
from the senses, which are
sufficient to produce them,
and do not differ essenti­
ally from images and sen­
sations.

Doctrine of Innate Ideas
Ideas differ essentially
from sensations and images
and are not derived from
the senses (nor therefore
from things, with which
our senses alone are in
immediate contact).

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The answers which philosophers have given to the
problem of human nature correspond strictly with the
position they adopt towards the problem of abstrac­
tion. The sensualists, at least so far as they are faithful
to the logic of their doctrine (Condillac, for example,
was not), deny either that the soul exists (materialists),
or that we can in any case know its existence (phenomenalists). The defenders of innate ideas, on the other
hand, tend to regard man as a pure spirit which
happens to be joined to a body—how, they find it
difficult to explain (dualism or exaggerated spiritualism) ?
Finally, the school of Aristotle and St. Thomas teaches
that man is a composite of two substantial principles,
each incomplete in itself and the complement of the
other, one of which is a spiritual and immortal soul
(animism).
Philosophy of Aristotle and St. Thomas (Animism)
Two principles each incomplete in itself, one of which
(the rational soul) is spiritual, form together a single
substance (the human composite).
Error of Defect
Error of Excess
The human soul does not
Man is a spirit acci­
exist (materialism) or is dentally united to a body
unknowable (phenomenal­
{exaggerated spiritualism) :
ism).
the soul and the body are
two substances each com­
plete in itself (dualism).

We should remark further that the position adopted
by philosophers towards the origin of ideas also deter­
mines their attitude to the general problem of the
1 This tendency recurs even in Kant (especially in ethics), though
he, like the phenomenalists, denies that reason can demonstrate the
existence of the soul.

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nature

existence of things known by the senses (the sensible
or corporeal world) and of things invisible and
spiritual, accessible to reason alone.
Philosophy of Aristotle and St. Thomas
(also of common sense}
It is impossible without absurdity to doubt either the
existence of corporeal objects (attested by the senses)
or the existence of spiritual objects (proved by reason).
Systems more or less
Systems more or less
Idealist
Materialist
The world perceived by
Nothing exists which is
not perceptible by the the senses has no real
senses and material {abso­ existence {absolute idealism} ;
lute materialism} ; or at or at least its existence is
least its existence is un­ unknowable and doubtful
knowable
{phenomenalist {phenomenalist idealism}.
materialism and positivism}.

M

I??

IV
CRITICISM (EPISTEMOLOGY)

In studying man philosophy is dealing with an
object which already by an entire portion of itself
transcends the corporeal world, that is to say, the world
of sensible nature. But it has the power and duty to
go further, and since its distinctive object is the being
of things, it must study that being no longer as
corporeal, sensible, or moving (the subject-matter of
the philosophy of sensible nature), but simply as being ;
consequently it must study being under an aspect
absolutely universal, and as it is present not only in
visible things but also in things which possess no
corporeal, sensible, or mobile being ; that is to say,
in things which are purely spiritual. This is the
object of that branch of philosophy which is philosophy
or wisdom par excellence, and is known as the first
philosophy or metaphysics.1
CRITICISM (EPISTEMOLOGY)

But before undertaking this study, the philosopher
must secure against all possible attack or distortion the
1 The name metaphysics originated in the fact that in the catalogue
of Aristotle’s works drawn up by Andronicus of Rhodes, the treatise
dealing with the first philosophy (Ilepi rijs irpcirys </>iXoao<f>las, the title
probably which Aristotle himself would have given to it) comes after the
books which treat of nature (Merà rà <¡>wiko). It would seem, however,
that chronologically Aristotle followed the same order in the actual
composition of his works.

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principles of this sovereign science, which are also the
principles of all human knowledge. For it is the
office of wisdom to defend its own principles and those
of the other sciences.
It will therefore be necessary, before studying being
in itself, as such, to study the relation of human thought
to being. This is the object of a special department of
metaphysics, known as criticism, because it has the
function of judging knowledge itself. Logic shows
how and in accordance with what rules reason attains
truth and acquires knowledge ; this in turn pre­
supposes the possibility of true knowledge (a possibility
attested by common sense and evident by the light of
nature). Criticism submits this presupposition to
scientific treatment, showing in what the truth of
knowledge consists, and establishing by a reflex
argument that true, certain, and scientific knowledge
is undoubtedly attainable.1

What is the truth of knowledge, and is it possible to
refute those who question the veracity of our organs of
knowledge, particularly of the intellect or reason ?
This clearly is the double question which arises at the
outset. The answer, however, is sufficiently plain.
As to the first question, there is no difficulty in under­
standing what is meant by the notion of truth. What
is a true or truthful word ? A word which expresses,
as it really is, the speaker’s thought ; a word in
1 By thus distinguishing criticism (epistemology) from logic, and
making it the first part, special introduction, or if you prefer,
apologetic introduction, to metaphysics, we are faithful to the
arrangement and divisions of Aristotle himself, who discusses
criticism briefly {Metaph., iv) before studying the great problems of
being as such.

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conformity with that thought. What, then, is a true
thought ? A thought which represents, as it really is,
the thing to which it refers ; a thought in conformity
with that thing. We therefore conclude that truth
in the mind consists in its conformity with the thing.
It is impossible to define truth otherwise without
lying to ourselves, without falsifying the notion of
truth of which in practice we make use, in the living
exercise of our intelligence, each time that we think.
We may further remark that a thought false in all
its constituents is an impossibility for, being in
conformity with nothing whatsoever, it would be the
zero of thought. If, for instance, I affirm that stones
have a soul, this is undoubtedly a complete error. But
it is true that stones exist, true also that certain beings
have a soul ; that is to say, all the constituents which
compose this false thought are not false. Therefore
error itself presupposes truth.1
We may also observe that if man were really and
seriously to doubt the veracity of his organs of
knowledge he simply could not live. Since every
action or abstention from action is an act of trust in
that veracity, action and inaction would alike become
impossible. A man therefore who attempted to carry
out in his life the thought truth is impossible for me would
inevitably lose his reason. Nietzsche, who was a great
poet but regarded belief in truth as the ultimate
bondage from which the world should be delivered,
made the experiment to his cost.
1 Cf. Sum. Theol., ii-ii, q. 172, a. 6 : Sicut se habet bonum in rebus,
ita verum in cognitione. Impossibile est autem inveniri aliquid in rebus,
quod totaliter bono privetur : unde etiam impossibile est esse aliquam cognitionem
quae totaliter sit falsa absque admixtione alicujus veritatis.

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As for the sceptics, who doubt, at least theoretically
and in words, the reliability of our organs of knowledge,
especially of the intellect or reason, it would obviously
be waste of breath to attempt to demonstrate its
reliability to them. For every demonstration rests on
some previously admitted certainty, and it is their very
profession to admit of none. To defend human
knowledge against their attack it is sufficient (i) to
show in what that knowledge consists and how it is
attained ; (ii) to refute the arguments they adduce ;
(iii) to make a reductio ad absurdum. When they say
that they do not know whether any proposition is
true, either they know that this proposition at any rate
is true, in which case they obviously contradict
themselves, or they do not know whether it is true,
in which case they are either saying nothing whatever,
or do not know what they say. The sole philosophy
open to those who doubt the possibility of truth is
absolute silence—even mental. That is to say, as
Aristotle points out, such men must make themselves
vegetables. No doubt reason often errs, especially in
the highest matters, and, as Cicero said long ago, there
is no nonsense in the world which has not found some
philosopher to maintain it, so difficult is it to attain
truth. But it is the error of cowards to mistake a
difficulty for an impossibility.
Conclusion IX.—The truth of knowledge consists
in the conformity of the mind with the thing.
It is absurd to doubt the reliability of our organs
of knowledge.
On this question of the reliability of our organs of
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knowledge philosophers may again be divided—
roughly—into three groups :
(a) The sceptics, who, impressed by the enormous
number of errors put forward by men, and especially
by philosophers, doubt the trustworthiness of reason,
and affirm that truth is impossible of attainment.
The principal representatives of scepticism are, among
the ancients, Pyrrho (360-270), the neo-Academics
(Arcesilas 315-241 ; Carneades, 214-129) and the later
Greek sceptics (Aenesidemus, first century a.d., and
Sextus Empiricus, end of the second century) ; in modern
times Montaigne and Sanchez in the sixteenth century,
and pre-eminently David Hume in the eighteenth.
The philosophers called anti-intellectualists, because
they despair of intellect and reason, and look for truth
to the will, to instinct, feeling, or action (Rousseau,
Fichte, Schopenhauer, Bergson, William James, the
modernist and pragmatist school), must be classified with
the sceptics, because, although they do not, like the
sceptics strictly so called, declare truth unattainable,
they maintain that it is unattainable by the organ whose
distinctive nature it is to discover truth, and because
by rejecting the intellect and reason they effectually
deprive man of his sole normal means of attaining it.
(¿) The rationalists, on the contrary, are of opinion
that truth is easy to attain, and therefore undertake to
bring all things within the compass of reason, a human
reason which has no need to submit humbly and
patiently to the discipline, whether of reality itself, a
teacher, or God. In the first case they tend to
subjectivism, which takes as its criterion of truth the
knowing subject, not the object to be known ; a
position which is the dissolution of knowledge. In the
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second they tend to individualism, which calls upon each
philosopher to work out a philosophy entirely his own,
and create an original and novel view of the universe
(Weltanschauung). In the third, they tend to naturalism,
which claims to attain to a perfect wisdom by the
unassisted powers of nature, and rejects all divine
teaching.1
The father of modern rationalism was Descartes
(seventeenth century), to whom Malebranche, Spinoza,
and Leibniz traced more or less directly their
philosophic pedigree. But its first principles and true
spirit were revealed by Kant (end of eighteenth
century), who completed the Cartesian revolution ;
his pantheistic successors, Fichte, Schelling, and Hegel,
deified the human subject of knowledge. Through
Kant, and the subjectivist philosophy which traces its
origin to him, rationalism, as before in the era of the
sophists, has joined hands with its opposite (scepti­
cism) , and become absorbed in the anti-intellectualism
of the modernists (end of the nineteenth and beginning
of the twentieth century).
(c) The school of Aristotle and St. Thomas teaches
that truth is neither impossible nor easy, but difficult
for man to attain.
It is thus radically opposed alike to scepticism and
to rationalism. It sees in the multitude of errors put
1 Naturalism rejects divine teaching in these two different ways :
( I ) It denies God the right to teach men truths in themselves inaccessible
to the unassisted reason {supernatural mysteries'). (2) It also denies him
the right to teach men by revelation truths in themselves accessible to
unassisted reason (truths of the natural order, philosophic truths—for
example, the immortality of the human soul) which reason can indeed
discover by its unaided powers, but always with the risk of mingling
error with truth, whereas revelation brings them within the reach of
all, easily and without any admixture of error.

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forward by men and particularly by philosophers a
sign indeed of the weakness of the human under­
standing, but a reason to prize the intellect the more
dearly and to embrace truth the more ardently, and
an instrument for the advancement of knowledge by
the refutations and explanations which these errors
call forth. And, on the other hand, it recognises that
reason is our sole natural means of attaining truth, but
only when formed and disciplined, in the first place
and pre-eminently by reality itself (for our mind is
not the measure of things, but things the measure of
our mind), secondly by teachers (for science is a
collective, not an individual, achievement, and can
be built up only by a continuous living tradition), and
finally by God, if he should please to instruct mankind
and bestow upon philosophers the negative rule of
faith and theology.1
Philosophy of Aristotle and St. Thomas
{Moderate Intellectualism)
That which really is the cause of truth in the mind.
Reason is capable of attaining with complete certainty
the most sublime truths of the natural order, but with
difficulty and only when duly disciplined.
Error by Defect
Error by Excess
Reason is incapable of
Reason attains truth in
attaining truth, which every sphere easily and
either is wholly inaccessible without any need of sub­
to man {scepticism) or must mitting to any external
be sought otherwise than discipline {rationalism).
by the intellect {anti-intellectualism).
Synthesis of these Two Errors
The mind of man makes the truth of that which he
knows (namely, phenomena), and that which really is,
the thing in itself, is unknowable by reason {criticism
or Kantian agnosticism).
1 See above, p. 124.

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Another question, among those with which criticism
is concerned, demands consideration here. The
intellect or reason being the instrument of philosophy,
what is the formal object of the intellect, to which
intellectual knowledge relates directly and in itself?
To answer this question it is sufficient to ask oneself
whether there does not exist an object which is always
present to the mind when the intellect functions ?
Such an object does exist. Whatever I know by my
intellect, there is always some being or mode of being
present to my mind. There is, however, nothing else
except being which is always present in this way.
If, for example, I think of a quality, a magnitude, or a
substance, in all these cases alike I think of some being
or mode of being ; but there is nothing except being
which is common to these three objects of thought,
and therefore present in all three alike. We therefore
conclude that being is the formal object of intellect,
that is to say, the object which it apprehends primarily
and in itself (per se primo') and in function of which it
apprehends everything else.
To know the cause of a thing, its purpose, origin,
properties, and relations with other things, is in these
various ways to know what it is, to apprehend its
being under those different aspects. To use the
understanding without the notion of being arising is
an impossibility.
The intellect, moreover, is able to apprehend the
being of bodies in their sensible appearances (pheno­
mena). It is thus, for example, that in physiology it
studies the properties of living organisms in reference
to causes which themselves belong to the sensible
order. Of this nature are the sciences of secondary
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causes or the sciences of phenomena. But the intellect
can also apprehend the being of things in their first
principles. This is the function of philosophy as a
whole, which in turn is subdivided into natural
philosophy and metaphysics, according as the being
apprehended in its first principles by the intellect is
the being of bodies as such or being simply as being.
Psychology indeed deals with this question of the
formal object of the intellect. But the distinctive
function of criticism is to make clear that the being
with which we are here concerned is indeed the actual
being of things, which exists in them independently of
the knowing mind. To maintain on the contrary
that the object of our intellect is not the being of
things but the idea of being which it forms in itself,
or more generally that we apprehend immediately
only our ideas,1 is to deliver oneself bound hand and
foot to scepticism. For if that were the case, it would
be impossible for our mind under any circumstances
to conform itself to that which really is, and truth
would therefore be unattainable. Moreover, the
intellect would stand convicted of falsehood, for what
the intellect professes to know is what things are, not
what its ideas are. In reality ideas, as the conscious­
ness of every man witnesses immediately, are our
instruments of knowledge. If, therefore, knowledge did
not apprehend the things themselves, knowing would
be an operation or activity without end or object,
which is absurd. For to form an idea or judgment is
to know, just as to make use of a knife is to cut. And,
just as it is impossible to cut without cutting something
1 The doctrine of Descartes and after him of all subjective
philosophy.

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—the end or object of the act of cutting, which is not
the knife, but the thing cut by it—so it is impossible
to know without knowing something—the end or
object of the act of knowing, which is not the idea,
but the thing known by it.1
Conclusion X.—The formal object of the intellect
is being. What it apprehends of its very nature
is what things are independently of us.

From the two truths just enunciated, the intellect is
a truthful faculty, and being is the necessary and immediate
object of the intellect, there arises as a corollary a funda­
mental truth.
By intelligible we mean knowable by the intellect. But
to affirm that being is the necessary and immediate
object of the intellect, and that the intellect attains
true knowledge, amounts to saying that being, as
such, is an object of which the intellect possesses true
knowledge ; that is to say, that it is intelligible. And
to say that being as such is intelligible is to say that
intelligibility accompanies being, so that everything
is intelligible in exact proportion to its being. We
therefore conclude—
Conclusion XI.—Being as such is intelligible.
Everything is intelligible in exact proportion to
its being.
1 Intellectual knowledge comes into existence by means of ideas.
But ideas are simply that by means of which (id quo), not that which
(id quod) we know directly, a pure medium of knowledge, not (unless
reflexively) an object or term known. This is why we say that the being
of things is the immediate object of our intellectual knowledge (by
immediate we mean known without the intermediary of another term or object
previously known).

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It must be borne in mind that when we affirm
that everything is intelligible in exact proportion to
its being we mean intelligible in itself, to intellect, not
intelligible to us, to our intellect. If, indeed, as a
result of the inferiority of human nature, our intellect
is disproportioned to a being which exceeds it because
it is superior to man, that being, though in itself more
intelligible, will be less intelligible to us. This, how­
ever, is the case with all wholly spiritual natures, and
pre-eminently of God. In himself he is the most
intelligible of beings, but his intellect alone is pro­
portionate to this supreme intelligibility.

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ONTOLOGY :

ESSENCE

in criticism examined and defended the
principles of knowledge in general, whether scientific
or philosophic, we can proceed to the study of meta­
physics in the strict sense, that is to say, the science
of being qua being. This is the very heart of philo­
sophy. We have now to consider being as such, and
the great truths it contains in itself ; to inquire how
it enters into all things without being exhausted by
any ; to study its inseparable properties, unity, truth,
and goodness, to which we may add beauty ; and
finally to treat of it in its activity, and attempt to
penetrate the nature and modes of causation.
We must also examine how throughout the entire
created universe being is divided, whether we consider
the constitution of all created being (division of being
into potentiality and act, essence and existence) or the
different kinds of created beings (division of being
into substance and accident). We shall then realise that
the concepts elucidated by ontology are the key to
everything else. Certain among them are indeed so
indispensable that we must consider them here, for
indeed at every turn we are obliged to invoke the
primary concepts of essence, of substance and accident,
of potentiality and act. Though it is obviously impos­
sible in a mere introduction to give an analysis and
complete defence of these concepts, we shall try to

Having

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establish them with all due care, employing, it is true,
examples rather than developed arguments, and
simplifying matters considerably, but following never­
theless the order demanded by a strictly scientific study.
Although the notion of being, since it is the first
and best known of all, is evidently too clear in itself
to admit of definition in the strict sense, the first task
incumbent on a man who wishes to think seriously
is to clarify this notion in his mind, and with that
object to discover the primary conceptions into which
it is divided.1 We shall therefore begin by asking the
following question : What are the objects of thought
which inevitably and from the very outset impose
themselves upon the intellect when it considers being
as such, or to put it in another way, since being is the
primary object of intellect, what are absolutely the
first data of the intellect ? 1
2
We shall see that this one fundamental question
admits of three answers according as we adopt the
1 Cf. Aristotle, Metaph., v.
2 The notions explained in pp. igi sqq. present some difficulty to
beginners on account of their extremely abstract character. It is,
however, impossible to omit them, for they are literally of primary
importance. And in particular we are convinced of the urgent
necessity to define with the utmost care, from the very outset, the
fundamental concept of essence. Materials for the study of this concept
are scattered in different places, but is it not because we have forgotten
to collect them that the term essence, when we meet it on the threshold of
metaphysics, arouses to-day such suspicion, and, even if it forces itself
on our acceptance, leaves such vagueness in the mind ?
The student must therefore devote particular attention to the study
of the notions here explained, without, however, attempting to
comprehend them perfectly. For the moment it will be sufficient to
make his first acquaintance with them. Later when he meets them
again in ontology, after he has become more familiar with philosophy,
they will seem much easier.

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standpoint of intelligibility, of existence, or of action.
The consideration of the first of these standpoints will
lead us to determine what is meant by essence, of the
second to determine what is meant by substance (as
opposed to accident), of the third to determine what
is meant by act (as opposed to potentiality).
ESSENCE

We shall first consider being from the standpoint
of intelligibility ; that is to say, we shall consider
being so far as it is adapted to enter the mind, or is
capable of being apprehended by the intellect. This
is the most universal standpoint we can adopt, for
we have seen that being as such is intelligible and
hence that intelligibility is co-extensive with that
which is or can be. To the primary datum of the intellect
from this point of view we shall give the name of
essence.
(a) To consider being from the standpoint of
intelligibility or as it is capable of being apprehended
by the intellect is in the first place to consider it so far
as it can be simply presented to the mind without
affirmation or negation—in so far as it can be the
object of simple apprehension, as we shall term it later.
Triangle, polygon, seated, this man, are so many objects
simply presented to the mind without being affirmed
or denied.
From this point of view the primary datum of the
intellect is quite simply that which is placed at the
outset before our mind when we form the conception
of anything, or conceive the idea of it. Since we have
agreed to use the term essence in this sense, we conclude
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that an essence is that which in any object of thought
whatsoever is immediately and primarily {per se primo}
presented to the intellect : id quod in aliqua re per se
primo intelligitur.
Every idea whatsoever, unless it be, like the idea of
a square circle, a pseudo-idea involving a contradiction,
brings immediately before the mind something.
The something thus immediately presented to the
mind is an essence or a nature. When I think of man,
humanity, animal, goodness, white, whiteness, seated, triangle,
etc., each of the objects thus immediately presented
to my mind, each of these intelligible units is by
definition an essence in the wide sense of the word.1
An essence therefore is simply an object of thought
as such. Every essence, however, possesses its intelli­
gible constitution which distinguishes it from others
and involves certain attributes.
Here, however, an important observation must be
made. If I consider the triangle with its properties,
man, humanity, etc., they remain exactly what they are
as objects of thought, whether I suppose them actually
to exist or not. The fact of existence does not in any
way affect essences as such. To conceive them I
1 We have already seen that the individual as such is not directly
apprehended by our intellect. When indirectly, by a reflection on
the images (see above, p. 172), we form an individual concept, the
object presented to our mind by this concept, Peter, this man, this tree,
is also, so far as it is an object of thought, an essence in the wide sense
of the term. That is to say, the concept of essence in the wide sense
must be extended even to individual objects of thought. As for those
conceptual beings [blindness, for example, or nothingness) which present
nothing that really exists, the name essence is inapplicable to them for
the reason that a privation as such has obviously no essence. (See
St. Thomas, De Ente et Essentia, i.) Nevertheless, from our present
standpoint, we may call them improperly essences, in the wide sense.

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abstract from the fact that they do or do not actually
exist.
We thus perceive that being in the sense of existence
and being in the sense of essence belong to two distinct
categories.1 The term being has two wholly different
meanings. For example, in the quotation “to be
or not to be, that is the question,” being means existence,
but on the contrary in the phrase a living being it means
essence. In the first case the term being signifies the
act of being, the act, if I may so put it, which posits
a thing outside nonentity, and outside its causes
(extra nihil, extra causas) ; and in the second case it
signifies that which is or may be, that which corresponds
to some existence actual or possible. We may therefore
say that being is divided into essence and existence.
Í that which is : essence in the wide sense {essentia)
{ens) -j
{entitas) [act of being : existence {existentia)
being

The relationship which obtains between these two
terms is a problem which we shall study later ; it is,
beyond question, not simply with reference to ourselves,
like the problem of universals, but in itself the
fundamental problem of philosophy : are essence
and existence really distinct in all things except God ?
Actual existence, the fact of existing actually, is not
1 Observe that in existence itself we may distinguish two things :
existence as the fact of existing (existere in actu exercito) and existence
as an object of thought (existentia ut quod quid est). Regarded from the
latter point of view existence itself assumes the objective status of every
object of thought and confronts the intellect as a particular essence or
quiddity. Esse dupliciter sumi potest, scilicet in actu exercito ipsius existentiae,
et per modum quidditatis ; et ut exercet existentiam, addit supra seipsum ut quod
quid est ; et consequenter ut objectum intellectus est abstractius (quam ut objectum
voluntatis) : quia est objectum voluntatis secundum quod stat in actu exercito
existentiae, intellectus autem secundum quod rationem habet quidditatis cujusdam
in seipso. Cajetan, in I, q. 82, a. 3.
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included in the object of any of our ideas as such.
Our intellect can ascribe actual existence to a particular
object of thought only by basing itself directly or
indirectly by means of ratiocination on the witness
of our senses (or reflexively of our consciousness).
Thus it immediately judges sensible objects exist, I
exist, and demonstrates the existence of God by
arguing, for example, from the observed fact of motion.
It cannot by itself alone attain the actual existence of
the objects of its thought.
Those essences, on the other hand (such as triangle,
even numbers, humanity), which of their nature connote
only a possible existence (for which reason they are
also called possibles), are data furnished immediately by
our intellect and ideas.
We must now examine more closely this notion of
essence, or being understood as that which is or can be.
We have just defined an essence : that which in any
object of thought whatsoever is immediately and
primarily presented to the intellect : id quod in aliqua
re per se primo intelligitur. Let us see whether this
extremely wide concept (for it is applicable to any
object of thought) may not be subdivided and
qualified in such a way that the same definition taken
in a more restricted sense shall henceforward be
applicable, in each particular instance, only to a
particular object of thought.
(6) The mere presentation to the mind of an object
of thought (man, white) is but the beginning of
intellectual knowledge, which is perfect only in the
judgment by which the mind affirms or denies this
object of thought in reference to another (Peter is a
man, this flower is white). If then we would consider
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being from the standpoint of intelligibility, to discover
what is from this point of view the absolutely primary
datum of the intellect, we must consider objects of
thought so far as they can be apprehended by the
intellect when it judges, for example when it affirms
that Peter is a man. From this point of view which,
among the various objects of thought which can be
realised in a given subject, is that which the intellect
apprehends immediately and before everything else ?
We shall call it essence in the strict sense of the term.
Consider any object of thought, for example, Peter,
Paul, this dog, this bird: Peter is tall, Paul is laughing
and moving, this dog is barking, this bird is flying. Each
of these is a particular whole, individual, concrete,
and independent, completely equipped for existence
and action.
It is individual subjects of this kind that our mind
apprehends before anything else (from the standpoint
of existence) when we think of that which is. When
applied to objects of this kind the expression that which
is acquires a more definite and special force. It no
longer simply means that which corresponds to some
actual or possible existence, but that which fulfils in
the strictest sense and before everything else the act
of being. These objects are all, though in very
diverse respects, actors in the drama of the universe.
When, however, we adopt the standpoint of
intelligibility, our mind does not among the different
objects of thought which things can present apprehend
in the first place these individual subjects as such.
On the contrary the individual, as we have seen above,
escapes the direct grasp of the intellect. What I
know of Peter is what I know he is—for example, a
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man. It is such objects of thought as man or humanity
which it perceives in Peter, or such as white or whiteness
which it perceives in this flower, it is what a thing is that,
from this point of view, our mind primarily apprehends,
and it is therefore in this direction that we must look
for the absolutely first datum of the intellect in relation
to intelligibility (essence in the strict sense).
The concept of essence in the wide sense has thus
been subdivided into two. There is in the first place
that which in the strict sense is, that which. And in
the second place what a thing is, what.
BEING-

'that which is : essence iwhat
*n
w^e sense
' ^at which.

.act of being : existence

That which is in the strict sense we shall entitle the
primary subject of existence and action. It is what
philosophers also term suppositum and person. For the
moment we may neglect it, for, as we shall see, it
does not concern our present inquiry.
Let us, on the contrary, consider what a thing is. In
the notion of what a thing is there are further distinc­
tions and exclusions to be made, to determine more
precisely what is actually the absolutely primary
datum of the intellect from the standpoint of intelligi­
bility and therefore deserves to be entitled essence in
the strict sense of the term ; what, for example, is
the essence of Peter. Peter is seated. Peter is capable of
laughter. Peter is a man. Is what is here predicated
of Peter—seated, capable of laughter, man—in each of
these three cases, or in one alone, the being which
the intellect apprehends in Peter immediately and
primarily from the standpoint of intelligibility ? We
said above that every object of thought is, as such,
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an essence {essence in the wide sense). Now we are
studying what Peter is, and inquiring what is the
object of thought which constitutes the essence of
Peter {essence in the strict sense).

The following are the characteristics of the object of
thought thus defined, that is, of the being primarily
apprehended by the intellect when it considers what
a thing is.
It is at once plain that the being to which the
intellect is directed in the first place when it thinks
what a thing is, is a being which the intellect cannot
conceive that thing lacking or deprived of.
It is in fact in terms of that being that the intellect
immediately conceives, apprehends, grasps, sets before
itself and names the object in question. To deprive
the thing of that being, or to alter its constitution in
any way, would be to set before the intellect, by
definition, a different thing.
It is thus a being which that thing so far as it exists
cannot lack or be deprived of (otherwise the intellect
would not be truthful). For example, Peter, so far as
he exists, cannot be other than a man ; on the other
hand, he can be not seated.
The being in question is therefore a being which
the thing considered by the intellect is necessarily and
immutably.
Moreover, it is obviously the being which in the
thing possesses primary importance for the intellect,
since it is that to which the intellect is first directed.
It is thus the being which before anything else 1 the
1 It is plain that the word before denotes in this connection a priority
of nature, not of time.

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object is, and is, so to speak, the ground of what the
object is in other respects. It is the first being of the
thing. Peter, for example, is a man before he is
capable of laughter or mortal.
We conclude that the being to which the intellect is
in the first place directed when it thinks what a thing
is, is its necessary and first being, or, in short, the being
which constitutes the thing, what it necessarily and
primarily is.
This is the first characteristic of what we have
agreed to call essence in the strict sense.
There is a second. It was the standpoint of intelligi­
bility, it will be remembered, which we adopted
when we undertook this study of essence. Peter is a
man {rational animal) before being mortal. That is,
man includes animal, and in the notion of animal the
intellect finds the necessary characteristic, mortal.
The characteristics mortal and capable of laughter—
necessarily possessed by Peter—have in him a principle
and ground, which by its very notion, or by what
it is, or its own intelligibility, compels the intellect to
posit these characteristics, and this principle or
ground is one of the elements or aspects which con­
stitute the being man. It is from the standpoint of
intelligibility that Peter is a man before being mortal
or capable of laughter.
Thus if the being man is, as we have said, first, it is
in the order of intelligibility that it is first. In other
words, it is in Peter the first principle of intelligibility.1
However long our formula, we must say, if we would
express this truth exactly, that the being man is in
1 JVbre enim res intelligibilis est nisi per suam definitionem et essentiam.
St. Thomas, De Ente et Essentia, i.

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virtue of its constituent elements or aspects the root
of all the characteristics necessarily possessed by Peter 1
which have in Peter a principle which by its very notion
requires them.
This, then, is the second characteristic of what we
have agreed to call essence in the strict sense ; of the
being to which the intellect is directed in the first
place when it considers what things are. It is in the
thing the first principle of intelligibility.
Our intellect apprehends this being which is the
first principle of intelligibility in two ways, one
imperfect, the other perfect.
If, for example, we know that an object is a man,
without, however, being able to state what man is, we
possess a confused knowledge of the being in question.
Our intellect grasps that being, has truly apprehended
it, and really perceives it, but, so to speak, after the
fashion in which our eyes see an opaque object.
If, however, we know this same object and are able
to define what it is {an animal endowed with reason) we
now possess a distinct knowledge of the being in
question.
Our intellect not only perceives it, but also perceives
its principles or constituent aspects.
In the first instance the being in question is pre­
sented to us imperfectly, in the second perfectly, with
the perfection demanded by science, so that we can
employ it as a first principle of intelligibility. (For
example, from the knowledge that this thing is endowed
with reason I can deduce that it is capable of speaking,
laughing, worshipping God, etc.) But in both instances
it is obviously the same being which is presented to
1 These characteristics are termed properties.

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us. Therefore, though I do not yet know or even
can never know this particular being distinctly as a
rational animal, in itself it will be none the less (though
in this case I do not know how) in virtue of its
constituent elements the root of all the characteristics
which possess in Peter a principle requiring them by
its very notion ; it will be none the less in itself the
primary being of the thing as the first principle of its
intelligibility.
We now know what are the characteristics of essence
in the strict sense and are in a position to define it
as follow’s : Essence is the necessary and primary
being of a thing as the first principle of intelligibility,
or, in other words, what a thing necessarily and
primarily is as intelligible, in short, the primary
intelligible being of a thing : id quod per se primo
intelligitur in aliqua ref
'that which is : (what a thing is primarily y essence in the
as intelligible
Í strict sense
essence in the
BEINGwide sense that which : the subject of
action (suppositum, person)
,act of being : existence

1 Essence considered as an attribute of the thing (for example, man
when we say Peter is a man) is strictly what the thing is necessarily and
primarily as intelligible. Essence considered separately and in the
pure state (for example, when we speak of humanity or the being man, we
cannot say Peter is humanity or Peter is the being man) is strictly that in
virtue of which a thing is what it is necessarily and primarily as intelligible,
or, to put it in another way, that in virtue of which it is constituted
in a determinate degree of primarily intelligible being. If therefore we
consider essence in the pure state, we must substitute in our synopses
for the expression what the expression that in virtue of which :
’that which is : |ithat in virtue of which a thing is) essence in the
essence in the 1-, what
wnai it is primarily as urn
intelligible f strict sense
wide sense [that which : the subject of
BEINGaction (suppositum, person)
\_act of being : existence

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Conclusion XII.—The essence of a thing is what
that thing is necessarily and primarily as the
first principle of its intelligibility.
This primary datum of the intellect is termed by
philosophers not only the essence but also the quiddity
and nature. It is what Aristotle and the schoolmen
called the tó tl ijv elvai, the quod quid est,1 and which
they defined as id quod per se primo intelligitur in aliqua rep
a definition with which we were already acquainted,
but to which we have now attached a completely
definite sense.
The definition, when used of essence in the wide
sense, meant what a particular idea first presents to the
intellect. When employed of essence in the strict sense,
it means what a particular subjectprimarily isfor the intellect.
Observe that every object of thought, every essence
whatsoever {essence in the wide sense) is in fact the
essence of something {essence in the strict sense) appre­
hended more or less completely (in some or other of
its properties). When I think of animal, I apprehend
the essence of Peter in one part of its properties. When
I think of man I apprehend it as a whole. When I
think of Aryan, Breton, or Peter I apprehend it as a
whole with the addition of certain characteristics
or attributes derived from the matter (see below,
pp. 207-216). When I think of a living body endowed with
sensibility I apprehend the entire essence of the subject
1 The Latin equivalent of the Greek term is quod quid erat esse—as
St. Thomas explains (De Ente et Essentia, i), id est hoc per quod aliquid habet
esse quid, that which makes any object of thought this or that particular thing.
2 Or stated more fully : id quod primo in re concipitur, sine quo res esse
non potest, estque fundamentum et causa ceterorum quae sunt in eadem re : ut
animal rationale est hominis essentia.

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animal (and at the same time the essence of the subject
Peter in one part of its properties). When I think of
white or prudence, I perceive the essence of a particular
quality. When I think of goodness, unity, being, I
apprehend a certain created participation of the
Divine Essence (or I apprehend, lay analogy, if I think
of subsistent goodness, etc., the Divine Essence itself).
Observe, further, that every subject capable of
forming part of any proposition whatsoever 1 has an
essence distinctively its own, whether it be an individual
subject such as Peter {substantia prima, subject par
excellence), an abstract and universal subject {sub­
stantia secunda) such as animal, an accident, for example,
a particular colour or virtue, or a transcendental, for
instance the one, the good, etc.
The primary intelligible being of a thing is called
essence {essentia) because since the intellect is modelled
on being, what a thing primarily is for the intellect
must be that which is of primary importance in it
from the standpoint of being itself ; in fact, as we shall
see later, it is by and in its essence that a thing possesses
being or existence {esse).2 It is called quiddity {quidditas)
because it is that which the definition expresses and
declares, which in turn answers the question quid est
hoc ? What is this ? It is called nature {natura) because
it is the first principle of the operations for the per­
formance of which the thing has come into being {nata).’
1 With the exception of conceptual beings, which do not, strictly
speaking, possess an essence (see above, p. 192, note).
2 Essentia dicitur secundum quod per earn et in ea res habet esse. St.
Thomas, De Ente et Essentia, i.
3 Quidditas est ipsa rei entitas considerata in ordine ad definitionem explicantem
quid illa sit. Entitas vero rei considerata in ordine ad esse, dicitur essentia ;
in ordine ad operationem dicitur natura.

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The formal object of the intellect is being. On the
other hand, what we have agreed to term essence is
nothing but the primary intelligible being of a thing.
Our intellect can, therefore, really apprehend the essences of
things.1 To deny this would be to deny the intellect
itself, and to say that it is bound to miss what is
peculiarly its object.
Moreover, our intellect claims to give us knowledge
of the essences of things. The sciences which are its
work have no other aim than to grasp these essences,
either distinctly, to deduce from them the properties
of a thing (as when we know that a particular figure is
a right-angled triangle, or that Peter is a rational animal),
or confusedly, simply in order to place a thing in its
species and describe it (as when we know that a
particular body is sulphuric acid, a particular plant
alisma plantago). If therefore our intellect were
incapable of really attaining the essences of things,
it would deceive us. It is therefore an absolutely
necessary consequence of the fundamental axiom that
our intellect is trustworthy, that—

Conclusion XIII.—Our intellect is capable of
knowing the essences of things.
We do not maintain that the intellect always knows
the essences of things (in the totality of their
properties). The specific essences of things are often
1 It can also attain directly (by an appropriate concept) these
complete, i.e. completely determined, essences, at least in the case of
things immediately accessible to us, namely, bodies. (We attain, for
example, the complete, i.e. completely determined, essence of Peter,
when we know Peter not only as a living being or as an animal, but as
a man.}
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unknown to us, and undefined. This is due to the
imperfection of the human intellect. But we maintain
that our intellect is capable of knowing them—and
therefore does actually know them in many cases.
Neither do we maintain that the intellect can always
know the essences of things perfectly, that is distinctly.1
That it can often know them only confusedly 2 matters
little. What is certain is that it is capable of appre­
hending them. The eye, to take a parallel case, sees
the coloured objects within its compass with more or
less distinct detail ; it may require the assistance of a
magnifying glass, but it can see them.
It is important to bear in mind that the experimental
sciences are very far from being able to know perfectly
the essence of the things which they study. They are,
in fact, unable to attain a truly distinct notion of their
essences, and never possess more than a confused or
purely descriptive notion of them. They know them,
so to speak, after the fashion of a blind man by means of
indirect signs.
For example, we know distinctly the essence or
nature man when we distinguish man from the other
animals by the specific difference endowed with reason.
But we cannot know in the same fashion how the dog,
for example, differs from the lion ; we know it only by
differences of a purely descriptive kind. Often even
when we have before us a series of concepts of diminish­
ing generality, for instance, a living body, animal,
irrational animal, vertebrate, mammal, canine, dog, poodle,
1 Even so it can determine them only by means of an evident
character previously known by us (for instance, the faculty of reason in
human nature) which it perceives to be a necessary factor of its
constitution.
2 See above, p. 199.

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etc., ending with Gyp or Fido, we may not know what
concept (canine ? dog ? poodle ?) designates (in the
totality of its properties) the essence of Gyp or Fido.
This, however, does not alter the fact that somewhere
in the series of concepts in the list just given, and any
others which might be inserted among them, there
must necessarily be a concept which designates that
essence. (In fact, in the example we have chosen,
it is the concept dog, as zoology discovers by indirect
signs, and without being able to give us a truly distinct
knowledge of the essence thus apprehended.)
When we think of man, for example, or any other
object directly presented to the mind by a human idea
(an abstract idea), we put before ourselves something
stripped of individuality, something which, being
apprehended by a single concept, constitutes in our
mind a single, and solitary object of thought—which
is therefore in our mind something belonging to one
(man) and capable of existing in many (in all men), that
is something universal.1 Thus everything directly
apprehended by an idea of our intellect—and con­
sequently the essence of a thing—is in our mind as
a universal.
No doubt, considered as it exists in reality, the
essence is individuated, for it is then identical with a
subject, Peter for example, who is himself individual.2
1 See above, p. 159.
2 If, for instance, I can say Peter is a man, it is because the thing (the
material object) apprehended under the object of thought man is
identical with the thing apprehended under the object of thought
Peter. When I thus proceed from the existence of things in my mind
to their existence in reality, I must say that the object of thought man,
single in my mind, is multiplied in all the individuals in which it is
realised and is identical with each.

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But this condition of individuality is no part of the
very nature or inmost constitution of the essence, does
not belong to the essence of Peter as such, to its
character as an essence. If indeed the essence
considered in itself {secundum se) were individual, our
intellect could never know it, for everything directly
apprehended by an idea of the intellect is apprehended
as a universal.
Considered in itself {secundum se) the essence is
neither universal nor individual. It abstracts from
every condition and mode of existence, being purely
and simply what the object is primarily as intelligible
and what the definition expresses. Thus it is equally
present in the actual thing, individuated (in order to
exist) and, in our mind, universalised (in order to be
known). For example, we see a man only in public,
therefore in complete dress, whereas in his bedroom
he wears pyjamas. Nevertheless the man we know,
when we see him in the street, is the same man, because
his pyjamas are no more part of his nature than his
suit of clothes ; neither belongs to the man considered
in himself. Similarly considered in itself the essence
is not universal, but neither is it individual ;1 that is
to say, the essence as such, the essence of Peter taken
in itself, abstracts from all the characters which
distinguish Peter from Paul or John.2
1 Cf. Aristotle, Metaph., vii, 8, 1033 b 22 ; 10, 1035 b 14. Here we
are speaking only of corporeal things, which alone are immediately
accessible to us (being connatural to the human intellect), consequently
the only things whose essence is directly knowable (otherwise than by
analogy) and can be known complete, i.e. completely determined.
2 From all that has been said it follows that, when, for example,
we say Peter and Paul possess the same essence or the same nature, the word
same refers to the essence of Peter and Paul as it exists in the mind (for
then it is one and the same object of thought), not as it exists in reality

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Conclusion XIV.—The essences of things are
universal in the mind, and considered in them­
selves neither universal nor individual.
This proposition is of the first importance. To deny
it inevitably involves suspicion of the human intellect,
which cannot directly apprehend in its concepts the
individual as such ;1 we shall either demand from it
what it cannot give, a knowledge strictly superhuman
■—intellectual intuition of the individual—or deny
its objective reference and fall into subjectivism.
We must therefore bear firmly in mind that to know
the essence or nature of anything it is not necessary to
know the principles which constitute its individuality,2
since the essence, considered in itself, is, in fact,
nothing individual. Misconception of this fundamental
(for then it is identical with Peter and with Paul, two different
individuals). But since the essence in question is not individual in
itself (secundum se), in other words is not distinct in Peter and in Paul qua
essence, it follows that it is in Peter and Paul such that it can be appre­
hended by the mind in a single concept and constitute in the mind
one and the same object of thought. This is expressed by the statement
that the essence formally universal in the mind is fundamentally universal
in things or in reality. (The nature of anything exists in the mind
either in a condition of logical or formal universality, as, for example,
when we say man is the species of Peter and Paul, or in a condition of
metaphysical or fundamental universality, as when we say man is
mortal. The term fundamental here refers to the proximate foundation
of universality. When, on the other hand, we say that the nature or
essence is fundamentally universal in reality, we are speaking of the
remote foundation of universality).
1 We are now speaking of things known by our intellect and do not
deal with the question how the intellect knows its own individual and
material act.
2 Cf. St. Thomas, De Verit., q. 2, a. 4, ad 1 : Intellectus noster
singularia non cognoscens propriam habet cognitionem de rebus, cognoscens eas
secundum proprias rationes speciei.

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at the bottom, of the errors of several great
metaphysicians, Spinoza, for example, and
(exaggerated intellectualists), also Bergson
anti-intellectualists of the present day.

(«) The essence of corporeal things is universal in
the sense just explained. That is to say, in this category
of being there are a multitude of individuals possessing
the same essence.
Individuals possessing the same essence, for example,
Peter, Paul, and John, are on the same level in respect
of primarily intelligible being ; they are essentially
equal.
Nevertheless these individuals differ one from
another. Peter is fair, short, and sanguine, John dark,
tall, and choleric, etc.1 Such characteristics peculiar to
a particular individual are not derived from the
essence. Otherwise they would be identical in all
the individuals which by hypothesis possess the same
essence. They are therefore non-essential characters.
Nevertheless they are, in fact, unalterable and
necessary.12 If he were not fair, sanguine, etc., Peter
would no doubt be a man, but he would not be Peter.
We must therefore conclude that these characteristics
have their ground in what the object is necessarily and
primarily, but as an individual, or, in what we may
term the individual nature of the thing. (By individual
1 We are not now speaking of those purely contingent characteristics
which distinguish one individual from another, for example Peter is in
Paris, Paul in Rome, Peter is rich, Paul poor, etc. We are speaking of
those characters which arise out of the constituent being of the individual,
the innate characters, which are, radically at least, unalterable.
2 But in a fashion altogether different from the characters derived
from the essence (properties). See below, p. 212, note.

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nature we mean incommunicable to any other object
or, if you prefer, wholly circumscribed.)

(¿) In this individual nature we find, as in the
essence, the notes necessary and first being. But, on the
other hand, and this is the important point, it is not
the necessary and first being of the thing as first
principle of intelligibility ; it is not the first principle
of intelligibility. The individual characteristics such
as fair, sanguine, etc., are not, as we pointed out,
derived from Peter’s essence ; they are not required
by it. That is to say, they do not possess in Peter a
principle or ground which requires them by its very
notion, or in virtue of what it is, that is to say, of its
own intelligibility (as, for example, rational requires
capacity for laughter). Nevertheless, since they are
necessarily possessed by Peter, they have their root
in Peter, in Peter’s individual nature ; they have
there a principle.
They must then have as their principle something
which does not require them by its very notion,
in virtue of its being or of its own intelligibility,
something in the notion of which the intellect cannot
discover a necessity for these characteristics rather
than any others. Therefore, his principle is in itself
wholly indeterminate. If neither by its notion nor
in virtue of its being or its own intelligibility it requires
this rather than that, it is because in itself it has no
notion, being, or intelligibility. We are thus led to
a principle which of itself is absolutely nothing
conceivable, to first matter as Aristotle understood it,
something which can enter into the constitution of
a being, but is not itself a being.
o
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If it be admitted that non-being of this sort is part of
all corporeal things, and that when itself individuated
by some qualification 1 it is the primary root of their
individuality, it is easy to see that the characters
which are derived from the individual nature of the
thing, since their primary root is the individual
matter with the dispositions it happens to possess at
the moment when the thing comes into existence,
have, as their first principle in the thing, a principle
which does not require them by its very notion—for
in itself it has neither notion nor intelligibility ; it
requires them solely in virtue of the accidental
dispositions it happens to possess at a particular
moment.
Thus, the individual nature is not the first principle
of intelligibility, because it is by its matter that it is the
principle of the individual characters.2
(c) We have merely sought to indicate here how the
obscure notion offirst matter, the study of which belongs
1 In so far as it materia signata quantitate. Obviously beings wholly
incorporeal or immaterial {pure spirits') cannot derive their individuation
from first matter. They must therefore be individuated by their
essence itself, and each individual in consequence differs from the rest
as a horse, for example, differs from a man, each being by himself a specific
essence. For this reason in the order of pure spirits there are no two
beings essentially equal. And consequently in the case of pure spirits
(but only in their case) the essence is something individual and the
concept of complete essence identical with that of individual nature.
2 To avoid any possible confusion be it observed that an individual
nature is not unintelligible in itself. It is first matter that is unin­
telligible in itself. Though the individual nature is not the first
principle of intelligibility, is not the primarily intelligible being of the
thing, it is nevertheless the primary principle of its being, for it is the
essence as individuated by matter, and is therefore intelligible in
itself. That is why an intelligence more perfect than ours, the Divine
Mind for example, can know it directly.

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to natural philosophy, arises naturally in the mind
as soon as it is understood that considered in itself
the essence of corporeal objects is not individual, a proposition
itself demanded by the fundamental axiom of the
trustworthiness of the intellect.
We may further point out that since matter, this
species of non-being, is present as the ground of
individuation (and consequently as the primary root
of certain qualifications)1 only in the individual nature
(in Peter’s nature as such) and not in the essence
[humanity), we may regard the essence, the primary
intelligible being, as free from all the qualifications due
to matter as their primary root or as immaterialised
being,8 in other words as the archetypal being of the thing,3
1 That is the sense of St. Thomas’s dictum : formae et perfectiones rerum
per materiam determinantur {De Verit., q. 2, a. 2).
2 Aristotle, Metaph., vii, 7, 1032 b 14 : Xlyu 8'ovcrtav S.pev OXys rà rl ijv
elpai.,
3 Cf. St. Thomas, De Ente et Essentia, ii : Haec materia (signata) in
definitione hominis in quantum homo non ponitur ; sed poneretur in definitione
Socratis, si Socrates definitionem haberet. In definitione autem hominis ponitur
materia non signata . . . from this it follows :
(i) That Socrates possesses his essence not precisely as Socrates, but
as man, for the essence is that which the definition expresses {cf. De
Verit., q. 2, a. 2, ad 9) and Socrates, as Socrates, is indefinable. Socrates’s
individual nature is the essence of man individuated by the materia
signata.
(ii) That essence taken in the pure state or separately, as for instance
when we speak of humanity or the being man, may be regarded as the
immaterialised being (stripped of the qualities derived from materia
signata), or as the formal being of the thing as a whole (comprising both
matter—not individual—and form). It is in this sense that the ancients
gave to the essence (itself comprising the matter—not individual—■
and the form) the name ofform {forma totius) : Et ideo humanitas significatur
ut forma quaedam. Et dicitur quod est forma totius . . . sed magis est
forma quae est totum, scilicet formam complectens et materiam, cum praecisione
tamen eorum per quae materia est nata designari (St. Thomas, De Ente et
Essentia, 3). It is important to observe that, although the individual
matter (e.g. haec ossa, hae carnes) is no part of the essence or specific

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an ideal being which in the pure state or separately
has no existence except in the mind, and exists in
reality only as individuated by matter, in the concrete
state of the individual nature.
We must therefore conclude that there is nothing
more in the individual nature than in the essence from
the standpoint of primarily intelligible or archetypal
being.1 From this point of view all individuals of
the same species are on the same level of being ; to
nature, on the other hand the unindividuated or common matter
{ossa, carnes) is part of it. What constitutes man is not the soul alone,
but soul and body together. {Cf. Aristotle, Metaph., vii ; St. Thomas, In
VII Metaph., 1. io, 1492 and 1496, ed. Gathala). This unindividuated
or common matter, taken simply as receiving the form and determined
by it, and not as the primary root of certain characters (the individual
characters) of the subject, is made known to us by the form : materia
cognoscitur per formam, a qua sumitur ratio universalis (St. Thomas, loc. cit.
Cf. De Verit., q. 10, a. 4 & 5, and is part of that which we have here
termed the immaterialised being {archetypal being) or formal being of the
thing {forma totius, seu potius forma quae est totum).
1 The individual nature contains more (the qualities peculiar to the
individual, for example, a particular temperament) than the essence, but
only from the standpoint of matter, not from the standpoint of purely
intelligible or immaterialised being. The individual characters are
no part of that being and add nothing to it in its own order.
Remark in this connection that the individual characteristics {fair,
sanguine, etc.) from the very fact that they are derived from the matter,
are necessary, and unalterable in a totally different sense than are the
characters derived from the essence {properties). The latter are necessary
de jure, as derived from a principle constitutive of the essence which
demands them in virtue of its very concept ; it is absolutely impossible
that Peter should exist without being mortal. The individual characters,
on the contrary, are only necessary de facto, as derived from particular
dispositions of the matter which they presuppose. If it is impossible
that Peter should exist without possessing a particular temperament,
the existence of that characteristic presupposes certain material condi­
tions in virtue of which Peter possesses a particular individual nature,
but which are not themselves necessary. Hence these characters
can be to a certain extent modified, and are unalterable only in their
ground.

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know their (universal) essence is to know all there is to
know in them, for the being of Peter as Peter is no more
complete or determinate than the being of Peter as
man. It is merely more closely circumscribed.
We can now understand how, although the human
intellect cannot directly know the being of objects
in its individuality, its nature as an intellect is not
frustrated on that account, nor does it miss its formal
object, for it truly knows the being of things so far as
it is primarily intelligible or archetypal being.1 Hence,
though imperfect, it is neither useless nor untrust­
worthy.
(¿) Be it observed that the synonyms essence,
quiddity, and nature, all of which denote a universal,
may be stretched to denote something singular,
when we consider the essence {humanity, for example)
as individuated by matter (in Peter, for instance), or
as it possesses in reality a singular mode of existence.
Nevertheless, strictly speaking, the term nature alone
is compatible with the predicate individual, whereas
the expressions individual essence or individual quiddity
are incorrect.2
1 In all this we have in mind things immediately accessible to us,
namely corporeal things, which the human intellect cannot apprehend
directly in their individuality, because, since it is obliged to abstract
from images its wholly immaterial ideas, it is by that very fact compelled
to abstract from that which constitutes the materiality of sense know­
ledge, namely the individual matter.
As regards immaterial things {pure spirits), our intellect is equally
incapable of apprehending them in their individuality, but for an
entirely different reason ; because pure spirits are not immediately
accessible to us, and we can know them only by analogy, not in their
essence, and are unable to apprehend their complete essence.
2 So far at least as the order of corporeal things is concerned. In
the order of pure spirits, on the contrary, the essence is individual (see

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We have indeed seen that the terms essence and
quiddity are used in reference both to the existence and
the definition of anything. The definition, however,
can express only the primarily intelligible being of the
thing, for it states its constituent elements which are
by their very notion principles of intelligibility in it.
Hence the definition cannot express the material
individuating principles of the thing, and for that
reason the individual nature as such is indefinable.
Therefore, since the quiddity, what the object is as definable,
can only consist in the primarily intelligible being
of the object, it must be universal. Similarly, that in
virtue of which anything invites that supreme perfec­
tion which consists in existence can clearly be nothing
but its immaterialised being. For it is not in virtue
of that in it of which the first principle is matter
that it invites existence. Its individuality is merely a
condition in which it must be in order to exist. And
since the essence, what a thing is, taken precisely as that
in virtue of which it receives existence, can consist
in nothing but its immaterialised being, it must be
universal.
The term nature, on the contrary, is used in reference
above, p. 210, note 1). And if we know the essences of spiritual beings
after the fashion of a universal, it is because we only know them
inadequately and by analogy with the corporeal objects previously
known.
The expression individual nature is not uncommon in St. Thomas (cf.
De Verit., q. 2, a. 5, natura singularis; Sum. Theol., i-ii, q. 51, a. 1,
natura individui, etc.). He also uses, though exceptionally, the
expression essentia singularis (cf. De Verit., q. 2, a. 7). Whatever may
be thought of the propriety of the term, in any case St. Thomas
understands by it simply the essence individuated by the matter (not
in Spinoza’s sense, the essence complete, as an essence, only in the in­
dividual').

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to the operations which anything is adapted to
perform. A thing, however, does not act solely in
accordance with its archetypal or primarily intelligible
being, but also as it is subject to particular material
conditions and possesses a particular individuality.
Nothing therefore prevents our diverting the term
nature from its primary significance to denote
secondarily what a thing is as individual.
i what primarily as intelligible : essence,
what -j
quiddity, nature
{what as wholly circumscribed (essence
'that which is :
individuated by matter) : individual
essence in the
nature
wide sense
BEING that which : the subject of action
{suppositum, person)
.act of being : existence

Finally we may remark that in a series of concepts
such as substance, living body, animal, man, Aryan, Breton,
etc., only the concept man, strictly speaking, denotes
Peter's essence. The concepts substance, living body,
animal, denote only certain elements or intelligible
aspects which enter into the constitution of that
essence ; in other words, they denote that essence only
in one part of its qualifications, and the concepts
Aryan or Breton only as circumscribed and differentiated
by certain additional notes arising from the dispositions
of matter. Aryan and Breton are thus, like the essence
man, universal objects of thought apprehended by the
mind in the individual Peter and liberated by abstrac­
tion from the conditions of individual matter ; but
they are universals whose extension is less than that
of the essence, and which belong to a particular class
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(race) divided into a multitude of individuals
s.
mg. the same essence; and, since they can be
distinguished only by means of characters rooted
in certain dispositions of matter they cannot be the
subject of a notion strictly speaking distinct, or a
true definition.

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VI
ONTOLOGY : SUBSTANCE AND ACCIDENT

Adopting the standpoint of intelligibility, we asked
ourselves in the preceding paragraph what is the being
primarily apprehended by the intellect from that
point of view. We were thus brought to the notion
of essence strictly so-called, or nature (the two terms
may be regarded as synonymous) ;1 what an object
primarily is as intelligible.
Let us now consider the being of things no longer
in reference to intelligibility but in reference to
existence.
What from this new standpoint is the being which
immediately presents itself to the consideration of the
intellect, that to which the latter is directed before
anything else ? In other words, what is the being
primarily apprehended by the intellect as existing ?
We have already answered the question.2 What the
mind apprehends first of all as existing, is beings such
as Peter, Paul, this man, this dog, this bird, individual
concrete and independent subjects, fully equipped to
be and to act, and which we have termed the primary
subjects of action, supposita, or persons} It is they who
primarily fulfil the act of being.
1 See above, pp. 201, 213.
2 See above, p. 195.
3 The name person is reserved for supposita of an intellectual nature,
who are therefore masters of their actions and possess the maximum
of independence.

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The subject of action may be thus defined from the
standpoint of existence. It exists wholly by itself alone
or by its own means, not in the sense that it has no
need of a cause {Peter has been engendered and many
causes combine to keep him in being), but in the sense
that it is by itself sufficiently disposed to be drawn
from nothingness by the causes of its being ; taken
separately it possesses in itself or in its own nature
everything necessary to receive existence.1 In this
sense we may say that it is a being existing by itself
{per sé) or in virtue of itself, in virtue of its own nature,
ens per se existens. Since a being of this kind exists as
a whole and in no wise as part of another being or
subject in which it exists, we may also say that it exists
in itself, in se.
A being which exists per se2 or rather a being
immediately disposed to exist per se, is thus from the
standpoint of existence the first datum of the intellect.
Observe further, that when the intellect makes being
of this kind its object, it transcends the limits which
define the essence in the strict sense or the nature {what
a thing is, or rather—if we take the pure essence,
abstracted from the subject which possesses it—that in
virtue of which an object is what it is).
We are now concerned, as we have already
1 We are speaking here of created subjects. An uncreated (divine)
Person possesses in himself everything necessary to exist with an
underived existence. When we say that the suppositum is in no way a
part of the whole in which it exists, the term whole obviously means
a whole that is one in itself (see p. 250), not a collective whole, for example
the universe.
2 This formula is preferable, because existence itself cannot enter
as a constituent part into the definition of anything created. See
further St. Thomas, Quodlib., 2, q. 2, a. 4, ad 2 : ipsum esse non est de
ratione suppositi.

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hinted, with that which is in the strict sense, Peter for
example, and not with that in virtue of which Peter
is what he is {humanity, the property of Peter in
virtue of which he is a man, or his individual nature,
the Petrine humanity, so to speak, in virtue of which
he is Peter).
Í that which is : ( what (or that in virtue of which)
essence in the 1
being J wide sense I that which primarily exists : primary
subject of action (suppositum, person)
.act of being : existence

To be sure, that which is, Peter, possesses no distinctive
characters other than those which constitute what he
is or his individual nature. But when I say Peter I
conceive this nature as constituting the whole which
exists in nothing other than itself.1 When, on the other
hand, I say Peter's nature, I conceive that nature as
distinct from the whole which it serves to constitute
and as existing in him, in that whole.1
2 In short, the
1 Because I conceive it as possessed of a certain mode or fashion of
being which philosophers term subsistence or personality, and which
terminates it, somewhat as a point terminates a line.
In this introduction we make no claim to solve the problem
of subsistence (the distinction between nature and person) which
constitutes one of the most important problems of ontology. Adopting
the pedagogical standpoint of coherent exposition, we have merely
sought to present and classify notions, so that their sense and mutual
relationship may be understood by a synopsis which is complete from
the outset.
2 I conceive it in abstraction from the modality called subsistence
or personality which terminates it. Similarly I can consider a line
abstracting from the point which terminates it, in which case the
line thus considered is simply a part of the whole constituted by
the line and point taken together, and exists in that whole.

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subject of action possesses a nature or essence ; the
concept of that nature or essence taken as such {what
or that in virtue of which) is not the concept of the subject
of action {that which).
We will now turn to this nature or essence of the
subject of action. We have just observed that the
subject of action exists (is capable of existence) in
virtue of its own nature or its own essence.1 The
nature or essence of the subject of action is there­
fore that in virtue of which it is capable of existence
pure and simple {simpliciter) ; the nature of Peter
considered as the subject of action is that in virtue of
which I can say simply Peter exists.2.
Existence pure and simple is undoubtedly Peter’s
primary or first existence. But it is not his sole mode
of existence. He is sad to-day, yesterday he was
cheerful ; to-day he exists as sad, yesterday he existed
as cheerful. He has lost the former existence and
acquired the latter, but he has not therefore ceased
to exist purely and simply. That is to say, he possesses
a host of secondary qualifications in virtue of which
he exists not only simply {simpliciter) but also under a
particular aspect {secundum quid). It is thus that he is
a musician or a philosopher, ill or in good health, happy or
unhappy, etc. All these qualifications have accrued
{accidere) to that which he is primarily as existing, are
increments, or accretions, accidents.
Philosophy, health, happiness, sorrow ; all these are so
1 In virtue of its essence in the strict sense of the term in the case of
a purely spiritual subject, in virtue of its nature in the sense of
individual nature in the case of a corporeal subject. (See p. 235,
note I.)
2 That is to say, without regard to any particular point of view,
without modifying my thought by any addition.

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many essences 1 to which our attention has not hitherto
been directed, and which are not self-subsistent in
being, but on the contrary subsisting, so to speak, only
as coverings of the subject of action. Employing the
analogy of sensible objects we may say metaphorically
that the latter exists beneath the accidents {substat) and
supports them. From this point of view it may be
termed a substance* For example, we say that Peter is
a substance. Moreover, since his nature considered
precisely as such {what he is, that in virtue of which he
is what he is, that in virtue of which he is capable of
existence pure and simple), like himself exists beneath
the accidents, it also is entitled to the name of
substance, and we can speak of Peter's substance. We
have now distinguished the notion of substance as
opposed to that of accident*
1 The definition of essence given above (p. 201) is applicable
to accidents, if the subject is considered in a particular aspect.
Understood in a concrete sense, as attributed to the object (for example
sad when we say Peter is sad), the accident is what a thing primarily is as
intelligible in a particular respect (being sad is the ground on which Peter
possesses certain characteristics which necessarily follow from sadness).
Understood abstractly, and separately or in the pure state (for instance
when we speak of sorrow) the accident is that in virtue of which a thing
primarily is what it is as intelligible in a certain respect.
We may further use the term essence no longer in respect of the subject
Peter, but in respect of the accidents themselves, and say that sorrow
is that in virtue of which a particular passion primarily is what it is as
intelligible.
2 The subject of action is also called £nró<rra<ris (hypo-stasis), irpQn-ov
iiTroKetpevov, primum subjectum attributionis.
3 Observe that the term substance (substantia) corresponds to the Greek
word oi/oia understood in a restricted sense. The term oíala primarily
denotes essence or nature, but since substances are the first object which
the intellect attains, when it considers what exists, they are also for
that reason the first object which confronts the intellect with the notion
of essence ; in other words they are the first to merit the denomination
of essence or nature. Hence the term oíala, which taken in its most

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'that which is : (what a thing is (essence or in a particu­
essence in the I nature} and in virtue of
lar aspect : accident
wide sense 7 which it receives existI ence
absolutely : j
{that
which
primarily
¡-substance
exists (the subject of
action, suppositum, person)
act of being : existence
SUBSTANCE

The name substance is given, as we have just seen,
both to the subject of action itself {that which primarily
exists) and to its nature considered precisely as a
nature or essence {what a thing is, that in virtue of which
the subject of action is what it is and claims existence
pure and simple).1 What then shall be our definition
general sense denotes essence, and is afterwards divided into substance
and accident, has most naturally served to denote in a special sense the
first member of the pair, substance.
1 The subject of action (suppositum or person) is nothing but the
substantial nature completed by a particular modality (subsistence or
personality) which terminates it, as a point terminates a line (without
adding anything to it in its order of nature) and renders it absolutely
incommunicable. The term substance (corresponding to the Greek
oiata, which primarily denotes essence—see the preceding note) denotes
the substantial nature without defining whether or no it is terminated by
subsistence. It is therefore applicable alike to the nature (apprehended
by the mind without the subsistence which terminates it) and to the
subject of action (the terminated nature). But when we distinguish and
contrast the nature (not terminated) and the subject of action, the term
substance remains attached to the nature (not terminated) and is then
contrasted with the subject of action taken as such. Thus when we
speak of Peter’s substance, we mean precisely the nature in virtue of which
the subject of action Peter possesses primary being, and which is part of
him. And theologians use the term in this sense when they teach that
in the Divine Trinity the Father and the Son (two distinct Persons)
possess the same substance, are consubstantial, (¡¡¿oolmoi..
On the other hand, the Greek term viróarcuris (hypo-stasis, etymo­
logically the same formation as sub-stantia) after a certain vacillation in

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of substance ? Being receiving existence of itself {per
se) or in virtue of itself in the unqualified sense adopted
above ? No. For so understood the definition applies
only to the subject of action ; absolutely speaking, it
alone—Peter for example—exists as a whole, and not
as part of a being or subject in which it exists. Its
nature, on the contrary, is part of itself and exists in
itself. Peter’s nature exists in Peter, and is part of
Peter. It is true that since Peter is himself constituted
by it, and exists in virtue of it {per earn), this nature
does not exist in something previously existing which
receives it (as, for example, sorrow exists in Peter, who
was previously in existence). We can therefore say
that it exists (is capable of existence) per se, in the
precise sense that in order to exist it has no need to
be part of another being previously existing which
receives it in itself, but that on the contrary it constitutes
the whole (the subject of action) which exists by itself.
In this sense and, if we are careful to qualify and
explain our meaning, the description ens per se existens
is applicable not only to the subject of action, but also
to its nature, and may therefore serve as the definition
of substance.1
(The same is true of the expression ens in se existens.}
its employment, came finally to denote the subject of action taken
as such (person) and is used exclusively in this sense. It is thus
contrasted with substance understood as a nature not terminated by
subsistence.
Were we tempted to deny the vital importance of these abstract
concepts and distinctions, we might recollect that for the word biiooioios,
on which the true understanding of the Trinity depends, but which
differs only by an iota from the unorthodox term ójuowiftrios, Catholics
were willing, when the Arian heresy flourished, to suffer every kind of
persecution, and sometimes even death.
1 Cf. John of St. Thomas, Cursus philos., i, Log. ii, q. 15, a. i.

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We shall therefore1 define substance as a thing or
nature that can exist by itself or in virtue of itself {per
se)—and not in another thing {in alio), that is to say, in
a subject previously existing.2
(Alternatively we may define substance as a thing
or nature whose property is to exist in itself.)

Conclusion XV.—Substance is a thing or nature
whose property is to exist by itself, or in virtue of
itself {per se) and not in another thing.
It is evident that the idea of substance represents
something which really exists. If no substance
existed, no nature capable of existing in itself, all
natures would be such as could exist only in something
else. But in that case, since nature A could exist only
in nature B and nature B in turn only in nature C, there
would be an infinite regression which could never
1 Existence itself cannot be a constituent part of any created nature.
It is for that reason that substance must be defined as a thing or nature
capable ofexisting per se or apt to exist per se. The same observation was
made above in reference to the suppositum (p. 218, note 2).
We must make the sense of the suggested definition clear. If per se
(or in se) is understood in the restricted sense explained in the text, our
definition will mean : substance is a nature apt to exist per se (or in se) qua
nature or essence in the suppositum which it constitutes when terminated by the
subsistence. If, however, per se (or in se) is understood in the absolute
sense in which it was taken above (p. 218), the proposed definition will
mean : substance is a nature apt to exist per se (or in se) qua subject of action
(suppositum or person).
2 The term substance signifies a thing capable of existing in itself or of
subsisting ; that is to say, of being self-contained as an existent thing
(its function subsistere), so that, once it exists, it sustains in being the
additional qualities or accidents with which it is invested (its function
substare). But it is only as a suppositum that substance is immediately
capable of performing these two functions. Considered as a nature
or essence it merely seeks to perform them.

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reach a nature in which all these natures existed ;
they therefore could not exist.
Those philosophers who, like Fichte (nineteenth
century), denounced the “ dead substance of the
Latins ” to oppose to it “ Teutonic action or
becoming ” were fighting against the intellect itself,
which is simply unable to dispense with the notion
of substance and imposes it upon us as an absolutely
primary and immediate datum. Moreover, that which
they took for substance and declared “ dead,”
“ inert,” etc., was a mere figment of their own
imagination. For substance is not an “ empty
receptacle,” “ an inert and dead support.” It is the
absolutely primal being of a thing, the radical
principle of its activity and all its actuality. As
Aristotle said, substantia est primum ens.1 But to
perceive this a philosopher must make use of his
intelligence, rise above the animal fife of the senses,
and not be content to show his skill in handling words
devoid of conceptual content and freighted only with
material images.
The substance of an object, so long as that object
exists, is as such immutable.1
2
Peter’s substance is that in virtue of which Peter exists
purely and simply, that is to say, as Peter. So long as
Peter exists, his substance as such cannot change. And
when Peter’s substance does change (when Peter’s
body becomes a lifeless corpse} Peter exists no longer, he
is dead.
1 Metaph., vii, I.
2 No doubt when Peter grows the change affects Peter’s substance
itself, which increases, but solely in respect of its quantity. It does not
affect it as substance.

P

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Moreover, in itself substance is invisible, imperceptible
by the senses. For the senses do not apprehend being
as such, but present to us directly only the changing
and the moving. In a certain sense, to be sure, it is
indeed the substance of Peter that my eyes see, as it
was truly Jesus whom the disciples saw at Emmaus, but
my eyes thus apprehend the substance only in fact and
materially, not formally.
In other words the object seen or touched is some­
thing which while seen or touched is at the same time
also a substance ; but it is not seen or touched as a
substance. As a substance it is conceived, not seen
or touched, and so far as it is seen or touched it is
coloured or exerting resistance, not being and
substance. In the language of philosophy substance
is intelligible in itself (per se) and sensible only accidentally
(per accidens). That therefore in things which
possesses most importance for us escapes the direct
grasp of our senses and imagination, and is a pure
object of the intellect, since the intellect alone appre­
hends being as such (sub ratione entis).
Observe that, if from the standpoint of existence
substance is in things the being which is the primary
and immediate object of the intellect, on the other
hand to discover not only that a particular object
possesses a substance, but also in what that substance
consists, or what is its nature, we are obliged to take
our stand upon that which reveals this nature to our
senses, namely the operations, phenomena, or accidents,
of the substance. In this sense we know the substance
by the accidents.

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ACCIDENT

Consider now such things as the laughter, movement,
sorrow, joy, colour, etc., which I perceive in Peter, and
which make Peter exist in certain aspects. These
things are capable of existence. But they obviously
do not exist after the same fashion as substance.
To exist they must belong to another being previously
existing.1 They exist as something which belongs to a
being or subject already in existence. In this sense
we say that they exist in something other than them­
selves. 2

Conclusion XVI.—An accident is a nature or
essence whose property is to exist in something
else.
1 Previously—if not in the order of time, at least in the order of
nature.
2 The accident of which we are speaking is the predicamento! accident
which is contrasted with the substance. The term accident, when it is
contrasted with property and signifies a predicate not derived from the
essence (the predicable accident) has another meaning.
If we are thinking of the predicamental accident, or of the contrast
between substance and accident (a contrast between real beings), we
may say that the attribute relates to an accident (the intellect in virtue
of which a man is capable of laughter is an accident really distinct from
the substance). If, on the other hand, we are thinking of the predicable
accident, that is to say, of the contrast between those unreal beings of
logic (the predicables}, genus, species, specific difference, property, and accident,
it denotes not an accident but a property, an attribute predicated of the
subject, not as something which helps to constitute his specific essence,
but as arising necessarily from it.
Conversely, if we are considering the predicamental accident, we
must say that the individuating characteristics (the possession of a
particular temperament, or heredity) belong, radically at least, to the
substantial, not to the accidental order. If, on the other hand, we are
considering the predicable accident, we must say that these character­
istics are accidents (attributes predicated of the subject, neither as
helping to constitute the specific essence nor as derived from it).

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It follows that though an accident partakes, indeed,
of being, it does not exist as a being ; it is essentially
of a being, ens entis, and capable of existence only as
the complement or perfection of a being. Thus the
word being is predicable of the accident only in a
secondary and indirect sense, and whereas being in
the primary sense of the term is from the standpoint
of existence the subject of action, so that our intellect
apprehends immediately and of itself the subject of
action, the substance, that which exists in itself,
we find it difficult to arrive at a clear understanding
of the accident. To succeed we are obliged to
elaborate our notion of being, to make it more pliable,
plane it down, bind it to the real, in short, to apprehend
the accident by analogy with the substance which is
contrasted with it.
The mere fact that the term accident is a substantive
involves us in the danger of regarding the accident as
a substance, a piece of substance or a reduced
substance. The imagination intervenes, and we depict
to ourselves accidents and phenomena as fragments of
matter inlaid in the suppositum, like a casing of mosaic
or marquetry. Those for whom the words accident
or phenomenon evoke images of this kind miss the notion
of accident altogether. They conceive in fact only
pseudo-substances and are incapable of advancing a
step further in philosophy. An original effort of the
intellect elaborating the notion of being is here the
sole remedy.
It is obvious that things such as an act of thought
or a movement of emotion cannot be confused with
our substance, because they come and go, and change
within us, whereas our substance never ceases or
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changes, being as such immutable so long as we exist.
Nevertheless these things are realities which affect us
intrinsically. They are, therefore, really distinct from
the substance in which they exist or, in technical
language, inhere. There are thus contingent accidents
(such that the subject can exist without them) real
and really distinct from the substance.
But if change, by showing that there are in a subject
things which come and go, helps us to arrive at the
notion of accident, it is very far from being a necessary
attribute possessed by every accident. There are
things without which a subject cannot exist, and which
nevertheless are accidents, additional beings which
complete the substance ; our understanding itself,
for example, and our will are evidently something real
in us. But they cannot be confused with our substance.
For we possess a distinct notion of them wholly
extrinsic to that of substance,1 which would be
impossible if they were not essentially different from
the latter? Therefore the understanding and the1
2
1 We distinctly conceive the understanding or intellect as a faculty
of knowing whose object is being, the will as a faculty of conation
whose object is the good, substance as a nature or essence whose specific
property is self-subsistence. The three concepts fall wholly outside
each other.
2 We are able to reason in this way because we are dealing with
things proportionate to our intellect, which apprehends them by
a proper and distinct concept (things which are, we say, known by
their essence). In such cases, if two concepts are wholly external to
each other, it is because the things they present to the mind really
differ one from the other. Otherwise our intellect would deceive us.
It is in this way that we prove that quantity or extension is an accident
really distinct from corporeal substance, and that in every created
thing the essence is really distinct from the existence. (On the latter
point see John of St. Thomas, Cursus Phil., Phil. Nat., q. y, a. 4.) When,
however, the distinction is due to the standpoint from which the mind

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will are real things in us distinct from our substance,
consequently accidents (belonging as we shall see
later to the category of quality). There are, therefore,
necessary accidents (without which the subject cannot
exist) real and really distinct from the substance.
The different schools which profess conflicting
doctrines on the problem of substance may be repre­
sented roughly by the following scheme :
Philosophy of Aristotle and St. Thomas
There are as many substances as there are individuals.
In virtue of its substance each of these possesses primary
being, but there are in each real accidents really distinct
from the substance.
Substantialists
There are no real acci­
dents really distinct from
the substance, which is the
sole reality.
Descartes, Leibniz, and
especially Spinoza. The
German pantheists of the
nineteenth century.

Phenomenalists
There is no substance ;
the accidents which are
apparent to the senses or
the consciousness (pheno­
mena) are the sole reality.
English sensationalists—
neo-Kantian school. Philo­
sophy of pure becoming.

Descartes denied the existence of real accidents
really distinct from the substance. He identified
corporeal substance with extension and the substance
of the soul with the act of thought. He thus set
views the same object we have indeed two distinct concepts, but not
wholly external one to the other. For example, I distinguish in Peter
his being a man and his being an animal, though in reality they are one
and the same being. But the concept man, far from being external to
the concept animal, implies it on the contrary.

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philosophy on a path which could only lead to
pantheism (for if there are no accidents distinct from
substance, every substance is its action—a perfection
which belongs to God alone—and the concept of
substance becomes identical with that of absolute
Being or God, with whom everything is thus confused),
or if pantheism is to be avoided, to the denial of
substance, which such a philosophy will do its
utmost to disprove and to banish from the human
intellect.
Spinoza erected on the Cartesian foundation a
monism or absolute pantheism from which Leibniz
attempted in vain to escape by substituting for the
single substance of Spinoza an infinite multitude of
individual substances (monads'], thus in effect replacing
Spinoza’s God by a boundless host of deities. Though
they rejected the notion of substance, for which they
substituted that of becoming or evolution, and regarded
the thing-in-itself not as an object which imposes itself
on the mind but as a background of the mind which
produced the object, the German metaphysicians in
the succession of Kant (Fichte, Schelling, Hegel) may
be ranked among the exponents of pantheistic substantialism since they posited a single principle which
constitutes by its development the stuff and reality of
all things.
In the phenomenalist camp the English sensationalists
and associationalists maintained that states of consciousness
(sensations, emotions, ideas, etc.) are the sole reality
accessible to us, and attempted to reduce the whole
of psychology to the mutual association of these states
of consciousness. The philosophers of pure becoming
(Bergson, in particular, who thus joins hands with

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Heraclitus over a gulf of twenty-five centuries) deny
the existence of anything permanent in things, and
maintain that change without any subject of change
is the sole reality. (In psychology these philosophers
are opposed to the former group inasmuch as they
substitute “ a continuous stream of consciousness ”
(W. James) for a mosaic or “host” of states of con­
sciousness. But they are agreed in rejecting the
notion of substance.)
Kant (eighteenth century) substituted for the dis­
tinction between substance and accidents in things
(substance and accidents being equally objects of
knowledge, the former by means of the second)1 an
opposition of two separate worlds, the world of things
as they are in themselves (things-in-themselves, noúmeno)
and the world of phenomena manufactured by our
mind. He regarded the thing-in-itself as wholly
unknowable, though he affirmed its existence. This
thing-in-itself, sought now in the subject of knowledge,
became all in all to the German pantheists of the
nineteenth century. Renouvier and the French neoKantians, on the contrary, taught that the thing-initself, the substance, is not merely unknowable but
absolutely non-existent, and the concept of it
chimerical.
The various phenomenalist philosophers just men­
tioned failed to perceive that what they really deny
is the accident, not the substance. What they under­
stood phenomena is a mere pseudo-substance expressed
by a concept ashamed of itself and self-contradictory,
a substance pulverised, melted down, emptied of real
subsistence, something which is not accident, but
1 See above, p. 226.

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being of a being, the pure complement of being, and
inconceivable except as correlated with substance.
Since they have never really understood what is
meant by substance, and posit, under the appellation
of phenomena, pseudo-substances, they quite naturally
refuse to admit another substance behind these pseudo­
substances of their imagination.
THE INDIVIDUALITY OF SUBSTANCE

The being primarily apprehended by the intellect
from the standpoint of existence (the substance) is
something individual. The intellect indeed appre­
hends it as individual, for it apprehends the being of
things only by turning to the sensations and images
which reveal things to us under the conditions of
their existence and in their individuality. Moreover,
that alone can really exist which is by nature a com­
pletely circumscribed and self-contained unit, or an
individual.
(a) Our intellect, it is true, can have no direct
knowledge of this substance in its individuality ; it
simply knows, by turning to the images from which
it derives its ideas, that this substance is individual,
it does not know in what its individuality consists ;
Peter’s substance is directly revealed to it only by a
universal idea. Peter’s substance thus perceived, in
abstraction from his individuality, is simply Peter’s
nature apprehended in the characters which constitute
his essence, strictly speaking. And since we say of man
that he moves, laughs, possesses understanding and will,
etc., as we say it (primarily and in the first place)
of Peter or Paul—since in consequence the property of
existing beneath the accidents, which strictly belongs
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to the subject and his individual nature, is thence
transferred to the nature of the subject stripped of its
individuality by abstraction—we shall also give the
name of substance, though in a secondary sense
{substantia secunda), to Peter’s nature, as apprehended
in abstraction from his individuality, that is to say,
the universal essence man or humanity. On the other
hand, by substance in the primary sense {substantia
prima), we shall understand the individual substance.1
It is now clear that when we consider the being
primarily apprehended by the intellect in material
things we stress either the individual being or the
universal being according as we consider this being
primarily apprehended in relation to existence or in
relation to intelligibility.
In relation to intelligibility the being primarily
apprehended in things by the intellect is the essence,
strictly speaking, which in itself is not individual and
exists in the mind in a condition of universality ; and
it is only in an improper sense that the term essence
is used of the essence individuated by the individual
matter (that is, of the individual nature).
In relation to existence, on the contrary, the being
primarily apprehended in things by the intellect is
1 In the Aristotelian and Scholastic vocabulary the term substantia
prima, oiala irpCrr-q, denotes (see above note) the individual nature of the
subject of action without determining whether or no it is terminated
by subsistence. Usually indeed it does in fact denote the terminated
nature, or subject of action, the hoc aliquid. It does not, however,
denote formally the subject of action taken as such and contrasted
with the (non-terminated) nature. That function belongs to the terms
suppositum and persona (yirbffra.rri.s'j.
Remark that the distinction between the subject of action and
the nature (non-terminated by the subsistence) is in the main due to
the Schoolmen. Aristotle himself did not make it explicitly.

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the individual substance,1 and it is in a secondary
sense that the term substance is used of the nature
stripped of its individuality by abstraction (that is,
of the essence in the strict sense)?
Here we may call to mind what was said above 1234*
about the individual nature. We see at once how
we should classify the different concepts with which
we have made acquaintance hitherto?

BEING'

what ' primarily as intelli­ in a particular respect : accident
the
gible (essence in the
strict sense) and in
sub­
ject I virtue of which it absolutely : substantia A
that which is :
exists
is
secunda
t primarily as complete­
essence in the<
wide sense
ly circumscribed (in­
■ substance
dividual nature) and
in virtue of which - substantia prima
it exists as such
that which primarily is : the pri­
mary subject ofaction (sup­
positum, person)
act of being : existence
1 Taken precisely as that in virtue of which the subject possesses its
first being, the substance, substantia prima, is the subject’s individual
nature. We said above (p. 214) that that in virtue of which a thing is
susceptible of existence is the universal essence, the reason being that
we were then considering precisely what is the ground on which a thing
is susceptible of existence, in contrast with that which is merely a
condition or state in which it must be in order to exist. Here, however,
we are dealing with that in which the existence of the thing considered
precisely as in the state necessary in order to exist is grounded, and
this is not the universal essence, but the individual nature of the subject.
2 Hence in the order of pure spirits and there alone (where no distinc­
tion exists between the individual nature and the essence, see above
p. 211, n. 3 ; p. 213, n. 2), the substance in the primary sense of the word
is also the essence, strictly speaking. In the material order, on the other
hand, substance in the primary sense of the word is the subject’s
individual nature, and it is only in a secondary sense that the essence,
strictly speaking, is called substance.
8 See page 209.
4 The quod and the quo. We have already observed (see above,
p. 200, note 1) that the essence taken in the concrete or as attributed

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(ô) Per se, a se, in se. We have defined substance
as a thing whose property it is to exist by itself (per se) or
in itself (in se). We must determine carefully the
exact sense of these expressions.
A thing is said to exist in itself (in se) when it does
not exist as part of a whole previously existing, but
to the thing (what a thing primarily is as intelligible) is not presented
to the mind in its purity ; it is in fact presented to the mind together
with the thing or subject which it determines. To possess it in its
purity, it must be conceived separately, without the thing or subject
it determines, as for instance when we speak of humanity or, to force
language, of the being man, the entity man. In that case it must be defined
as that in virtue of which a thing primarily is what it is as intelligible, or, in
other words, that in virtue of which a thing is constituted in a particular
degree of being primarily intelligible. For this reason it will be
better to substitute in our synopses for the term what the phrase that in
virtue of which. So we finally get the following table :
INTELLIGIBILITY ....

Peter exists and is in a particular respect :
what he primar­
whiteness
accident
ily is as intelli­
gible (essence in (absolutely :
the strict sense)
humanity . . substantia'
Peter exists and is
secunda
that which is :
what he primar­
essence in the
ily is as complete­
substance
wide sense
ly circumscribed Peter’s indivi-'
(essence indivi­ dual nature
duated by mat­
BEING
ter, the individ­
-substantia
ual nature}
prima J
'■that which primarily exists :
suppositum, person (id quod} . . . Peter? .... existence
act of being : that in virtue of which
(id quo} a thing is outside nothingness
or its causes : existence
. that in
virtue of
which
(id quo}

The distinction between the quod and the quo plays a part of the first
importance in the metaphysical analysis of things.

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itself constitutes the whole which exists. In this sense
Peter exists in himself.
A thing is said to exist by itself or in virtue of itself {per
se), when it is brought into existence in virtue of itself,
or of its own nature (by the causes on which it depends,
if it is a created nature). In this sense Peter exists per se.1
Philosophy makes frequent use of this expression,
per se. It always means in virtue of itself, in virtue of its
own essence {per suam essentiam)—whether the quality
under consideration forms part of the essence of the
thing or necessarily results from it as its principle (in
which case per se is opposed to per accidens) 2 or whether
we merely wish to state that the attribute under con­
sideration immediately pertains to the thing which does
not receive it through the intermediary of anything
other than its own essence (in which case per se is opposed
to per aliud). It is in this sense that the subject of
action exists per se, whereas the accident exists per aliud.
But the expression per se does not mean in virtue of
itself or of its own nature as the absolutely first principle or
as the complete and ultimate explanation. This is something
totally different, which is expressed by the phrase
a se, of or from itself (as opposed to ab alio). That which
is a se is evidently per se, but that which is per se is not
1 Existence/>«• se or in se can, we have already seen (see pp. 218, 223),
be ascribed, as it is understood in a more or less strict sense, either to
substance in general (that which exists per se and in se contains in itself
whatever is necessary in order to receive existence and is not part of
a previously existent whole) or exclusively to the subject of action
(suppositum or person, which contains in itself everything necessary in
order to receive existence, and exists in no respect as part of a whole).
2 For example, Peter is per se alive, endowed with intellect, and the
faculty of laughter, the artist is per se one who fashions objects. But
Peter is per accidens a sufferer from influenza or the heir to a large
fortune, the artist per accidens celibate or married, etc.

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by any means for that reason a se. That which exists
a se or from itself, possessing in itself the entire explana­
tion of its existence, is uncaused ; God alone is from
himself, a se.
Created substances on the contrary
{created subjects of action) are caused ; they exist per se,
in virtue of their essence ; they do not exist a se.
In their own nature they possess everything necessary
to receive existence, but not to possess an existence
not received from without. They are sufficient by
themselves to exist, in the strictly qualified sense that
they do not exist as something which belongs to some­
thing else, but, absolutely speaking, they are by no
means a sufficient ground of their own existence.
That which is a se cannot cease to exist ; that which is
per se without being a se can lose its existence.
The distinction between that which exists a se and
that which exists per se is perfectly clear. Nevertheless
certain philosophers have lost sight of it, notably
Spinoza, who ascribes aseity (a-se-itas) to every
substance. (From which it follows immediately that
there is only one substance, and that everything
is God—monism and pantheism). When indeed
Spinoza defines substance as that which is in itself and
is conceived by itself, he really means, as the context
shows,1 that which to be and to be conceived needs absolutely
nothing except itself. Descartes had already defined
substance ambiguously as res quae ita exsistit ut nulla
alia re indigeat ad exsistendum, a thing which exists in such
a fashion that it has need of nothing else in order to exist.1
1 Cf. Ethics, i, 7.

2 Principia Philosophiae, i, 51.

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VII
ONTOLOGY : ACT AND POTENTIALITY

When we studied being first from the standpoint
of intelligibility, then from that of existence, we saw
that the object primarily apprehended by the
intellect, being in the primary sense of the term, was
in the former case what we call essence, in the latter
what we call substance.
We must now consider the being of things (under­
standing the term being in its most general and
indeterminate sense) from the standpoint of action, in
reference to the manner in which things behave in
reality, or, if you prefer, in reference to what they do.
This new standpoint acquaints us with a third primary
sense of the term being.
(a) What is the first truth which the intellect grasps
as soon as it has formed the notion of being ? It is
sufficient to consider the notion to see at once that
what is, is (principle of identity), or again that what is,
cannot not be at the same time and in the same relation
(principle of non-contradiction). That is to say, that
everything is what it is, that it is not what it is not,
and that it is everything that it is.
We will now consider what things do, what is their
natural behaviour, what is the primar}' fact of experi­
ence grasped by the senses and consciousness. Things
change. The arrow flies, the animal runs, what was
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cold becomes hot under the action of fire, food becomes
flesh, what was living dies, and every spring that which
had no being comes into existence.
Although, like all our primary notions, it is very
difficult to explain scientifically, everybody knows by
experience in what this great fact of change or motion
consists. We may say that wherever there is change
there is a transition (from one being to another, or
from one mode of being to another). And for
transition to exist, there must be something which
undergoes it, something which is the subject of change,
for example a subject which ceases to be in a particular
place or a particular thing (terminus a quo, the arrow
pressed to the bow, the food, the seed), to be in another place
or another thing (terminus ad quem, the arrow in the
target, flesh, the mature plant).
There is no change without a subject which is
changed, and which must be some particular thing
before the change is effected 1—in other words being
is prior to change.
Those, indeed, who maintain that change is prior
to being, and that there is change without a subject
which is changed and which is some particular thing
before the change is effected, deny the principle of
identity and fall into absurdity. For when they take
up this position, they must either continue to accept
the notion of being, in which case to affirm that there
is change without a subject of change, or that change
is prior to being, is to affirm that what has no being
1 For example, in a substantial change the first matter, which is not
a being, but potential being, is the subject which is changed and consti­
tutes a particular body, or particular being, by its union with a particular
substantial form, before it constitutes some other body by its union with
another substantial form.

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changes, which is manifestly absurd ; or they must
reject the notion of being as illusory and argue that
instead of conceiving being we must conceive change,
in which case they must reject as false, together with
the notion of being, the principle of identity which is
bound up with it, and maintain that thought is
essentially deceptive, which is equally absurd.
We are, therefore, absolutely obliged to hold that
being is prior to change, and that there is no change
without a subject which is changed, and which is some
particular thing before it changes ; or, in the language
of philosophy, that there is no motion without a subject
which is moved.
(¿) We will now turn away from experience and
every sensible representation and attempt to consider
change with our intellect, that is to say, in terms of
being, the formal object of the latter. We shall
inquire how or in what respect the starting-point of
change can thus become the goal. You will answer,
perhaps, that it is according as it is this or that, in
respect of what it is, that the starting-point becomes
the goal. But the starting-point is nothing but what
it is, and is already everything that it is, and therefore
in this respect is incapable of becoming, for it already
is. You may then say that it is according as it is not
this or that, in respect of what it is not, that the startingpoint becomes the goal. But in respect of what it is
not, the thing is nothing whatever, is pure nothing,
and therefore cannot be the source of the product of
change. It is incapable of becoming, for it simply
is not.
Hence the starting-point of change cannot become
its goal—either in respect of what it is or in respect
Q
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of what it is not. In other words, the new being which
is the product of change can be derived neither from
the being which already exists, nor from a nothing,
which has no existence whatever. Is change, therefore,
impossible, as Parmenides maintained ? And are we
obliged with him to deny the evidence of our senses,
which witnesses to the fact of change?
(c) No. But we are obliged to develop and explore
our idea of being. Evidently in the analysis we have
just made something has been left out. The startingpoint of change is no doubt already everything which
it is, but it is not yet all which it can be ; it is not yet
that particular thing it is destined to become, but it
possesses the means to be it, it can be it. Therefore
between being and not being there is the power of being.
It is neither in respect of what it is, nor in respect of
what it is not, but in respect of what it can be that
the starting-point of change becomes its goal.
The arrow is here (on the bow, for instance) and from
the standpoint of being pure and simple, it is nowhere
else ; but it can be there {at the goal, for example),
and possesses the means to be there. Bread is bread
and nothing but bread, and not flesh, so far as it is,
in the sense of being pure and simple, that is to say,
of being completely realised ; but it can cease to be
bread and become flesh. There is in it that which
enables it to undergo the change under the action of
certain determinate causes.
POTENCY OR POTENTIALITY

Things therefore are not confined and held fast by
what they are and what they are not. Even while
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they are here and not there, this and not that, they
possess the power to be there and no longer here,
that and no longer this. But so long as they are here
or are this, that power which they possess remains
mere power and is not manifested.
This power in them is as such something real.
Consider a man asleep. He neither sees nor speaks
nor walks. But he is not therefore blind, paralysed,
or dumb. He is really capable of seeing, speaking,
and walking. While he does not speak he retains
the power to speak, he has it in him ; whereas he
cannot without a violation of nature become a tree
or a bird. Or again take a billiard ball at rest. It
is immobile (not moving). But it is not therefore
immovable. It is really capable of motion. While it
does not move, it retains the power of being moved,
it has it in itself ; whereas it has no natural power
of passing through a wall. The power of being is not
being in the full and primary sense of the term ; but
power of being without as yet being is not sheer non­
entity. Power of being taken precisely as such is irre­
ducible either to nonentity or to being pure and simple.
It is something different from either, something sui
generis for which philosophy must find a place. Pre­
cisely so far as things can be something they are not,
they, after an inferior fashion, are.
We have thus found something which does not
deserve to be called being, on which that title can
be bestowed only in a secondary and improper sense,
as an alms, so to speak, but which nevertheless is real.
It is what philosophers term potency or potentiality.
In using the term potency we must be on our guard
against ambiguity. This potency is not that of which

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we think when we say that a being is potent. This
potency is not an active power ; power to effect
something or to work, at least when understood as
active, is the absolute contrary of the power or potency
with which we are now concerned, being not potency
but act. The potency of which we are speaking is
entirely passive, nothing more than a real power of
being or becoming. Wax is in potency to receive the
impress of the seal, water in potency to become ice or
vapour. The active powers (for instance, the faculties
of the soul) are also rightly termed potencies or potenti­
alities, but only in so far as they are not, or are capable
of not being, actually operative, or so far as they are
simple capacities of action or operation.
ACT

Since, however, power of being, though not nothing,
is not being in the full and primary sense of the term,
we must find a name for being in the full and primary
sense of the term as distinguished from potentiality.
Philosophers call it act.
Here also we must beware of ambiguity. We are
not concerned, at least not primarily and chiefly, with
an act in the ordinary sense of the word, with doing
or action. Action or operation is indeed an act, being
in act, but it is what is termed the secondary act {actus
operationis'). Action presupposes being. And the
primary act is the act of being {actus exsistentiae), more­
over of being a particular thing {actus essentiae). For
example, a body is luminous in act, even when it is
not illuminating anything else. Clay, once modelled,
is a statue in act, water at 320 Fahrenheit is ice in act,

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and the moment anything effectively is one thing or
another and especially the moment anything exists,
it is in act.
Act may therefore be defined as being in the strict
sense of the term, taken in the fullness thus signified,
or again the finished, the determinate, or the perfect as
such. Potentiality, on the other hand, is the determin­
able, the perfectible, that which is capable of being
finished, as such ; not a being but a real power of
being.
We must take care not to attempt to think with
our imagination these concepts of act and potentiality.
They can be thought by the intellect alone. Least of
all must we conceive of potentiality as some sort of
being in act which we imagine as more or less hazy,
indefinite, inactive, and hidden in the object. Poten­
tiality in itself is absolutely incapable of being repre­
sented. It is not a spring or an organ hidden in the
thing, nor a character prefigured in it after the fashion
of an imaginary statue outlined beforehand by the
veins of marble within the block, nor yet an act thwarted
or rendered abortive, like an effort or pressure over­
come by the resistance of an obstacle. It is absolutely
nothing done or in process of doing, absolutely nothing
in act. In itself it cannot be conceived (for in that
case it would necessarily be conceived as something
determinate). It can be conceived only by means of
the act (the particular thing) with which it is corre­
lated, as the simple power of being that particular
thing.

Conclusion XVII.—Being, considered in relation
to the fullness and perfection which the term
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signifies, is divided into being in the strict sense or
act, and power of being or potentiality.

We are now in a position to understand change.
The product of change arises neither out of being in
act nor out of nothing, but from potential being. In
other words, the action of the efficient cause draws,
educes, from the potentiality of the subject the deter­
mination, the form, which was wanting in the startingpoint of the change and characterises its goal, as when
the action of fire educes from the potentiality of
water (the water is cold, but can be hot) the determina­
tion (a specific intensity of heat) which characterises
it as the result of the change. The change is the
transition from potentiality to act, or, more accur­
ately, according to a definition to which we must
return later, it is the act of a thing in potentiality taken
precisely in respect of its potentiality : actus exsistentis in
potentia prout in potentia.
ACT AND POTENTIALITY IN THINGS

From what has been said it follows that all change­
able things, in whatever respect they are subject to
change, are compounded of potentiality and act.
God alone, since he is absolutely unchangeable, is
devoid of any potentiality. Since he is subsistent
Being itself or the Fullness of being, he is incapable
of becoming ; there is no perfection which he does
not possess or rather is not already ; he is pure act.
The being of all other things, on the contrary, is
too poor and too weak to realise simultaneously
everything they are capable of being. For every one
of them there is really open a vast range of possibilities,
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of which they can never realise more than a few, and
that by changing.
Here we may observe that the obscure and mysterious
concept of first matter whose acquaintance we made
when we studied the notion of individual nature is
that of a pure potentiality in the order of substance,
which can be any and every body and by itself is none.
It is the purely potential principle which in union
with an actual principle (a substantial form) constitutes
a particular corporeal substance, and is the subject
of substantial changes.
Potentiality and act divide between them the
totality of created being, both in the order of substance
and in the order of accidents. In other words, they
are, like being itself, transcendental objects of thought
which exceed or transcend every limitation of class
or category, and include all created things. The
substance of bodies is compounded of potentiality
{first matter) and act {substantial form). The substance
of incorporeal things {pure spirits') is not composite ;
it is in respect of that which constitutes its nature or
essence wholly act. But it is not therefore pure act
(in the case of pure created spirits), for this substance
{substantial essence) is itself potentiality in relation to
that which is the ultimate act of everything real
{actualitas omnis formae) or existence : pure spirits do
not derive their existence from themselves, a se ; they
can not be.
On the other hand, we may remark that every
accident {whiteness, strength, virtue, etc.) is an act
{accidental form) which determines the subject and is
itself sometimes in potentiality in respect of further
determinations. The intellect, for example, is an
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accident (an accidental form) whose subject is the soul,
and it is in potentiality in respect of a particular act
of thought.
It is clear that all the notions with which we have
become acquainted hitherto can be classified in the
following fashion :
' uncreated being : God, ens a se ...........
primarily as in­ ' in a particu­
what telligible (ess­
lar respect :
the
ence in the strict
sub­ sense) and in vir­ absolutely : 1
that ject
substantia
tue of which it
BEINGS
which is
secunda
exists
is :
'■primarily as com-\
essence .
pletely circum­
in the
scribed (individ­
ual nature) and
creat­ wide
ing* sense
i n virtue of
substantia
which it exists
* prima
as such
that which primarily is :
the primary subject
of action (supposit­
um, person)

\ act of being : existence................ .

.pure act
accident (^ac­
cidentalform)

substance
composed (in
the corporeal
order) of potentiality
and act, and
itself actualised by the
ultimate
act of every­
thing real
'

After what has been said, it is sufficient to consider
the notions of potentiality and act to see immediately
the truth of the following Axioms :
(i) Potentiality cannot exist in the pure state, apart
from any act. This is evident. For, since existence
is an act, potentiality can only exist in beings which
are in some other respect in act.1
1 Hence first matter cannot exist separately unactualised by some
particular substantial form. Similarly essence is in relation to the
act of existence a potentiality really distinct from existence but actual
in virtue of existence.

248

being
com­
pounded
of poten­
tiality
and act

ontology:

act

and

potentiality

(ii) Nothing is educed from potentiality to act except
by some being in act. It is plainly impossible that
that which is in potentiality, that which is capable
of having a determination or a perfection but does
not have it, should give to itself what it lacks, so
far as it does not possess it, that is to say, so far as
it is in potentiality.
(iii) Act is prior to potentiality. A consequence of
the preceding axiom.1
(iv) Potentiality is essentially relative to act and is
for the sake of the act {potentia dicitur ad actum).
It is indeed only in relation to the act that the
potentiality can be conceived (only in relation to
being white that we can conceive the power of being
white) ; and it is also only for the determination or
perfection that the determinable and the perfectible
as such are.
(v) Act and potentiality belong to the same order ; that is
to say, both must be in the order of substance, or
both in the order of accident. For it is evident that
every act which at the same time completes and
specifically determines a potentiality must belong
to the same order as that potentiality. The activity
of thought, for example, belongs to the order of
accident like the faculty itself from which it proceeds
and which is in potentiality to that activity.
(vi) Everything acts according to its nature in act.
1 This axiom is the metaphysical explanation of the truth previously
affirmed : being is prior to becoming or change. Absolutely speaking
this is true. In the order of material causality on the other hand
potentiality is prior to act, becoming prior to being, the seed prior to
the tree. But the seed itself presupposes the tree which produced it
and at the beginning of the entire process the actuality of the First
Cause.

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Since activity is an act {actus operationis') which is
brought into being by the subject from which it
proceeds it presupposes (as laid down by Axiom ii)
that the latter is in act to the extent to which it
produces that activity. The same truth differently
enunciated is expressed by the dictum action or
operation manifests being {operatio sequitur esse).
(vii) The combination of two beings in act cannot
produce something which is one of itself. We call one
of itself {unum per se), as opposed to one by accident,
a thing which constitutes a single being and not a
conjunction of beings, in other words a thing which
is one in virtue of the nature by which it exists.
For example, a living organism is a unit of itself,
whereas a machine or a house is an accidental unit.1
This distinction once understood, it is plain that
two beings in act, and as such constituting two
beings, can never by their combination constitute
anything except a conjunction of beings, that is to
say, an accidental unit.2

Once more on this question of act and potentiality
we find philosophers divided into three great schools.
The school of Aristotle and St. Thomas teaches the
distinction between potentiality and act, the priority
1 No doubt, if you destroy the unity of the machine or the house,
you destroy the machine or the house, but you do not destroy the
natures (or substances') of which it is composed (iron, steel, bricks, etc.).
Destroy, on the other hand, the unity of an organism, you destroy its
very nature (substance).
2 This axiom plays an important part in natural philosophy and
particularly in psychology. For instance, the Cartesian conception
which regards the soul and the body as independent of each other,
two complete substances, is unable to explain the substantial unity of
the human being, because two complete substances are two beings
in act.

25O

ontology:

act

and

potentiality

of act to potentiality, the reality of motion and
becoming, but the priority of being to motion. It
also shows that between God (the pure act) and all
things besides (compounds of potentiality and act)
there is an absolute and infinite difference.
Exaggerated intellectualism (Parmenides, Spinoza,
Hegel) refuses to admit the notion of potentiality,
because by itself it is obscure. If, however, everything
which is, is wholly act or pure act, either motion must
be unreal (Parmenides) or contraries identical (Hegel)
and creatures must possess the same nature as God
(pantheism).
Anti-intellectualism (Heraclitus, Bergson) equally
rejects the distinction between potentiality and act, but
because the notion of being is in the opinion of these
philosophers illusory. If, however, being is denied in
favour of becoming or pure change, pure act can no longer
exist ; and however the exponents of this school may
struggle to escape the logic of their position, God must
possess the same nature as things (pantheism).
Moderate Intellectualism
{School of Aristotle and St. Thomas')
Potentiality and act in things. God or the pure act
is absolutely distinct from created things.

Exaggerated Intellectualism
No potentiality in things.
Everything is absorbed
either in pure being, or in
the contradiction which
constitutes becoming, and
created things are identified
with God.

Anti-intellectualism
Neither act nor being.
Everything is absorbed in
change or pure becoming,
and God is identical or
continuous with things.

Material and formal, virtual and formal (or actual),
implicit and explicit, in accomplished act, in express act.
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In connection with the notions of potentiality and
act philosophers use certain expressions whose meaning
must now be explained.
We have just learned the meaning of the two
correlatives in potentiality and in act. The marble
before it has been carved is a statue in potentiality ;
as soon as the sculptor has given it the form he intends,
it is a statue in act.
(«) Closely related to these expressions in potentiality
and in act are the expressions so frequently met in
philosophy material and formal. They have been
borrowed from natural philosophy (cosmology)
which proves that every corporeal substance is
compounded of two principles, first matter (pure
potentiality in the order of substance) and substantial
form or first act.1
The terms material and formal have passed from
natural philosophy into all branches of philosophy, to
designate, by analogy, on the one hand whatever, in
itself indeterminate and potential, plays the part of a
subject which receives a determination, on the other
hand whatever possesses of itself a determining, actualising, and specificatory function, or again whatever
is taken as possessing a particular character, in a
particular aspect. It is in this sense that, as we have
already seen,8 we distinguish between the material
and formal objects of a virtue, science, or faculty.
Hence arises in particular the distinction between
the material and formal statement. We speak
materially when we do not take the things of which we
speak precisely as possessing the characters denoted by
the words we use ; we speak formally when in the
1 See above, pp. 166-168.

2 See above, p. 106.

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ontology:

substance and

accident

things of which we speak we consider not so much the
subject which possesses these characters as the
characters themselves, with the sharp contour and
clear-cut line they describe in it. This distinction is
extremely important. Formal statement should, in­
deed, be the constant aim of philosophy ; and, on the
other hand, many propositions are true formaliter
loquendo which are false materialiter loquendo, and vice
versa. For examples the following propositions are
true understood formally, but false if understood
materially :

Everything which is, is good (so far as it is).
The common good is always preferable to the good of
the individual (provided the common good is under­
stood formally, in which case the union of the soul
with God, that is with the transcendent common good
of all creatures, is to be preferred to everything else).
Superiors ought always to be obeyed. (So far as they
are superiors, and command nothing opposed to the
orders of a superior of higher rank.)
There are men who are natural slaves. (If slave is
understood formally, as meaning destined for manual
or servile work.)
Every virtue is stable. (If we consider solely its
quality of virtue.)
Knowledge is infallible (so far as it is knowledge).
Conversely, the following propositions are true only
in a certain context, and if understood materially.1
1 It would be of interest to show how philosophy, since it has given up
the technical language of Scholasticism, has increasingly tended to use
terms in a material rather than a formal sense. Hence a number of
badly stated problems, and a host of misunderstandings both between

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PHILOSOPHY

This picture is the Adoration of the Magi.
This book is the philosophy of Pythagoras.
Speech has been given to man to conceal his thoughts.
Philosophy is proud.
The British Constitution is good because it is illogical.

(Z>) We must be careful to distinguish in potentiality
from virtual, for they signify entirely different things.1
A thing is said to be virtual, or to exist virtually, when it
is contained in another thing of superior rank, not in
its being or proper determination (its formality) but
under another being or determination (another
formality), so that it is truly there according to the
virtue or degree of perfection which belongs to it, but
not formally or actually. In this case, the being in
which it is found is not in potentiality in respect of it,
but on the contrary in act after a higher fashion.
Its superiority is, so to speak, an obstacle which
prevents the thing which it virtually contains from
being present with its proper and inferior determina­
tion {formality).
Thus the perfections of all corporeal objects exist
modern philosophers themselves, and still more between the modern
philosophers and the ancients, with their formal terminology.
It may also be observed that certain philosophic terms understood in
a material sense, have acquired a meaning totally different from their
original significance. Take, for example, the term object. For the
ancients the object meant what is placed before the mind or presented to it,
considered formally as such. Hence imaginary beings, the chimaera
for example, were said to exist objectively or as objects present to the mind,
but not really or as things existing outside the mind. The moderns, on
the contrary, understand by an object the thing itself or the subject
which is presented to the mind, and to exist objectively is therefore the
same as to exist really or outside the mind.
1 Observe, however, that the expression potentially, in potentia, is
sometimes used improperly in the sense of virtually.

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potentiality

virtually in God, conclusions are virtually contained
in the premisses, partial lives exist virtually in the life
of an organism.
(c) We must now call attention to the fact that the
contrast between implicit and explicit is not to be
confused with that between virtual and formal (actual).
A thing contained implicitly in another may be there
formally or actually, not virtually : but it is present in
a confused fashion, wrapped up and hidden as a flower
lies hidden and folded in the bud. For example, in
the truth Peter is a man there is implicitly contained
the further truth Peter is a rational animal.
(d) Finally a thing given formally and explicitly
may be in act in two different ways. Take, for instance,
a man who is running as fast as he can to escape his
enemies. ïf I say he is fleeing I mention what he is
doing in express act (in actu signato) (what he is doing as
stressed or expressed, so to speak, by his intention).
If, however, I say that he is accelerating the rate of his
breathing I mention what he is doing only in accomplished
act (in actu exercito).
Similarly, a man who reads Ronsard, Lamartine, or
Victor Hugo, to count the number of times they use
the words aimer or chérir, reads the poets, to be sure,
and reads them formally and explicitly, but that is
not what he does in intention. On the contrary,
when we consider his object in reading the poets, we
must say that he is preparing an essay of stylometric
literary criticism. We may say that he reads the poets
in effect or in accomplished act, but that expressly
or in express act he is preparing the essay in question.
Again, when we repeat lilia agri non laborant neque
nent, thinking solely of the meaning of the sentence,

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what we then know in express act is the lilies of the
field, which are present to our mind as neither toiling
nor spinning. But at the same time we know in
accomplished act the nominative plural, lilia, which in
turn we shall know in express act, if we return to
the sentence in question and submit it to grammatical
analysis.
That is to say, the phrase in express act (in actu signato}
is used of things to which intellect or will are directed,
when they are the object of a concept of the intellect
or an intention of the will specially formed for them,
and are thus presented to the mind or brought into
being under the actual heading or on the actual ground
expressed by their name. When on the contrary
they are presented to the mind or brought into being
on occasion of something else and without being
intended in themselves, we say that they are present
only in accomplished act (in actu exercito}.

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VIII
THEODICY (NATURAL THEOLOGY)

Metaphysics studies being as such, but for that
very reason is obliged to study the cause of being.
That is why its highest branch, the coping-stone? so
to speak of the entire metaphysical edifice, is con­
cerned with him who is subsistent Being itself. This
branch of metaphysics is called natural theology (the
science of God in so far as he is accessible to natural
reason, or, from another point of view, so far as^he
is the cause of things and author of the natural order).
Since Leibniz it has also been known by the less
appropriate name theodicy.
Leibniz in his Theodicy (1710) undertook to defend
Divine Providence against the attacks of the sceptics
(particularly Bayle). The term theodicy (etymologi­
cally : justification of God) has been used since that
time to denote the branch of philosophy whose object
is God. But the name is objectionable on two grounds :
first because the providence of God has no need to
be justified by philosophers ; secondly because provi­
dence and the problem of evil are neither the sole nor
the most important questions of which natural theology
has to treat.
The primary questions discussed by natural theo­
logy are obviously those which concern God’s existence
itself.
For the existence of God is not in fact, as MaleR
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PHILOSOPHY

branche and the ontologists believed, evident to us
immediately and prior to any discursive activity of
the mind ; it is in virtue of that intellectual operation
which is the activity most profoundly distinctive of
man, namely ratiocination, that it becomes evident to
us, and to attain that certainty reasoning must proceed
not from the mere idea or notion of perfect being (the
ontological argument of St. Anselm and Descartes)
but from facts whose existence is established beyond
dispute. St. Thomas, resuming the entire tradition
of the past, shows by five different arguments how
the conclusion God exists is imposed with absolute
necessity on the human reason. There exist in the
world motion or change ; beings and events newly
brought into being ; things which are and are capable
of not being ; things graded in degrees of perfec­
tion, whose perfection, which consists in being, is more
or less limited, obscured, mingled with imperfection ;
irrational natures disposed towards an object or end,
as is proved, not only by the complex system of the
universe or the structure of living organisms, but even
by the simple aptitude of every agent to produce its
specific operation. To account for these various facts
we are compelled—for under pain of absurdity we are
obliged to stop at an ultimate explanation of existence
—to admit a cause which moves without being
moved, causes without being caused, cannot lack
existence, contains in its purity the perfection of which
tilings partake in greater or less degree, possesses an
intellect which is the final ground of all natures and
the first principle of all things. Such a cause we
term God ; it is pure act, deriving its existence from
itself {a se~). In other words, being itself is its nature
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THEODICY

(NATURAL

THEOLOGY)

or essence, it is subsistent Being itself, he who is. This
conclusion, which for the philosopher involves the
most sublime truths of metaphysics, is reached very
simply by common sense, for it is in truth the most
fundamental natural operation of the human under­
standing, so that it can be denied only by denying
reason itself and its first principles (the laws of identity
or non-contradiction, sufficient reason, causality) ; and
as the history of philosophy shows only too plainly,
the mind has no other choice than between the alter­
natives : “ the true God or radical irrationality.” 1
It is also the province of theodicy to show with
what manner of knowledge we know God and in due
course to study his nature and perfections, in particular
the unity, simplicity, and immutability which are immedi­
ately deducible from the perfection of underived
existence (aseity), the fundamental character of pure
act, and which prove most clearly that he is abso­
lutely and essentially distinct from the world ; his
relations with the world, his knowledge, his activity
as Creator and Mover ; and finally the problems
involved in the divine foreknowledge of contingent
events, particularly man’s free acts, and those arising
out of the existence of evil in the universe.
The school of Aristotle and St. Thomas teaches that
God is known by the natural reason analogically, so
that we perceive the divine perfections {being, unity,
goodness, wisdom, love, etc.) in the mirror of creatures,
without asserting any unity of nature, common
measure, or proportion, or mixture or confusion of
any kind between God and created things. This
1 Garrigou-Lagrange, Dieu, son existence, sa nature, Paris, 3rd ed.,
1920.

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teaching is opposed to two contrary errors, the error
of the agnostics, who maintain that the Divine Being
is beyond the ken of our intellect and God unknowable
by the reason (sceptics ; phenomenalists ; positivists
like Comte and Spencer, the Kantian school as a
whole), and the error of the pantheists, who confuse
the Divine Being with the being of created things
(Parmenides, Heraclitus, the Stoics, Spinoza, the
German metaphysicians after Lessing and Kant ; the
modernists and immanentists').
Philosophy of Aristotle and St. Thomas
God is known by analogy and is absolutely distinct
from creatures.
Pantheism
God confused with creatures.

260

Agnosticism
God unknowable,

IX
THE PHILOSOPHY OF ART
ETHICS

*T*

he aim of the practical sciences is to know, not for
the sake of knowing, but to procure by some action
the good of man (other than the pure act of knowing
truth). But the good of man can be understood in
two different senses ; either of this or that particular
good or of the good which is in itself alone the good
of man and which, as we say, determines the signifi­
cance of human fife.
the philosophy of art

Of the different practical sciences which are con­
cerned with the good of man from the first standpoint
(that of particular goods, and not of the absolute
good of human life), none, as we have pointed out
already,1 is a philosophy. For none of these proposes
to regulate human action in reference to the supreme
cause in the practical order, that is (for in the practical
order the aim or end pursued fulfils the function of
cause or principle) in reference to the last end (the
absolute good of man).
Nor are these practical sciences sciences in the
strict sense, for they do not proceed by way of demon­
stration, drawing conclusions from their premisses.
1 See p. 149.

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They are rather arts than sciences, and belong im­
mediately to the wide category of art, not to that of
science.
The essential character of art taken in its complete
extension is to instruct us how to make something,
so that it is constructed, formed, or arranged, as it
ought to be, and thus to secure the perfection or
goodness, not of the maker, but of the object itself
which he makes. Art therefore belongs to the
practical order in the sense that it instructs us how to
make something, considering not the use we should
make of our free will but the manner in which the
work as such and in itself should be executed. We
may thus say that art is concerned with what is to be
made, factibile, koitjtov.
This formal character of making is fulfilled primarily
in the material objects produced or fashioned by
man (foe factibile in the strict sense). But in a wider
sense it is to be found also in works of a purely spiritual
nature. In this case it goes beyond the sphere of
practice as such, so far as practice is opposed to
speculation and signifies an activity other than that
of pure knowing. It is in this sense that there is
making in the purely speculative order (a form of
argument, a proposition, are works, but works of the
speculative reason), and there are arts, logic, for
example, which are speculative arts.
In order, however, to establish a general theory of
art and making we must have recourse to the highest
and most universal concepts and principles of human
knowledge. Such a theory therefore belongs to the
domain of philosophy.
The province of philosophy thus defined is indeed
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OF

ART.

ETHICS

practical, since it is concerned with making, and its
object is to order from above the branches of practical
instruction. Nevertheless, since it is in the strict
sense a science, it cannot be essentially practical,
but remains essentially speculative in virtue of its
object and method of procedure ; moreover, it is
extremely remote from actual practice. Indeed, not
only has it no concern with the application of the
rules of art to a particular work to be accomplished,
but further it formulates rules which are far too
general to be capable of such immediate application
and to be correctly termed rules of art in the strict
sense ; it is therefore practical only in an improper
sense and very imperfectly.
The individual arts alone (branches of study
essentially practical) possess rules sufficiently detailed
to be immediately applicable to a particular work,
and their application belongs solely to them. Further,
with the exception of the fine arts, whose object,
beauty, being itself universal and immaterial, enables
philosophy to perform effectively though from : a
remote height her office of supreme arbiter, the; arts
since they are devoid of any universal character, except
the fact of being arts, of which philosophers can7 take
cognizance, escape her jurisdiction almost completely.
If we would accurately describe this branch of
philosophy, we should term it the philosophy of making,
but we shall call it simply the philosophy of art.1 Here
1 The term aesthetics, which has now become current, would be
doubly incorrect here. Modern writers understand by the word the
theory of beauty and art, as though the philosophy of art were the place
in which to treat questions concerning beauty considered in itself (such
questions belong to ontology), and as though art were confined to the
fine arts (a mistake which vitiates the entire theory of art). Moreover,

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we must first inquire what is the nature of art, if it is
indeed, as St. Thomas teaches, a virtue of the practical
intellect, and how it is distinguished on the one hand
from the speculative virtues (understanding offirst principles,
knowledge, wisdom), on the other from the moral virtues,
prudence in particular ; how art is to be subdivided
and the different arts classified ; and finally what are
the first principles and distinctive conditions—though
solely of the highest and most general order—of those
arts which have beauty for their object (the yâze arts)
and which thus occupy a superior rank among the
arts.
ETHICS

The practical science which aims at procuring man’s
unqualified good, his absolute good, is that of morals
or ethics. Since its distinctive object is not the
the word aesthetics is derived etymologically from sensibility (aZafláro/uu
= feel), whereas art, and beauty also, are matters of the intellect, quite
as much as of feeling.
Scholastic textbooks do not usually devote a separate treatise to the
philosophy of art, and either study its problems in psychology alone,
or, the better to explain the concept of prudence, in ethics. It would
be necessary to classify the philosophy of art, like ethics itself, under
natural philosophy, if we kept to the single standpoint of the
specification of the sciences by their formal object. But if we adopt the
wider standpoint of the end to which the sciences are ordered, we must
distinguish practical from speculative philosophy, and it is equally
necessary to distinguish, in practical philosophy itself, the philosophy
of making and the philosophy of doing (çf. the author’s Art and
Scholasticism). This treatment presents the double advantage of
corresponding to a very marked trend of modern thought, which tends
to devote a special treatise (aesthetics) to the theory of art, and of
returning to one of Aristotle’s fundamental classifications : irâsra ôlîvom
■¡j irpaKTiK-ri h ttoliitikti h eeupijTucó {Metaph., ii, I, 1025 b 25). Cf. Top.,
vi, 6, 145 a 15, and viii, 1, 157 a 10 ; Metaph., vi, 1 ; Nic. Eth., vi, 2,
1139 a 27. Hamelin (op. cit., pp. 81 sqq.) makes a convincing defence
against Zeller of Aristotle’s real opinion on this matter.

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ETHICS

perfection of the works produced and fashioned by
man but the good and perfection of the agent himself,
or the use he freely makes of his faculties, it is in the
strict sense the science of action, the science of human
acts (in technical language, of the agibile or -pazxóv,
that is to say, of the free use, so far as it is free, of our
faculties).
Ethics is as practical as any true science in the strict
sense can be, for it teaches not only the most general
rules of remote application, but also the particular rules
applicable to the particular action to be performed.
But at the same time this science has in view, not
some particular secondary end, but the last end (the
absolute good) of man, the supreme cause in the
practical order. It is therefore a philosophy. It is
without qualification the practical philosophy.
Note.-—Though ethics is as practical as any science
in the strict sense can be, we must not therefore suppose
that it is essentially practical (no science vere et proprie
dicta is essentially practical), or that it is sufficient to
make men behave rightly. It supplies, it is true, rules
immediately applicable to particular cases, but it
has no power to make us constantly apply them as we
should in particular cases,1 in spite of the difficulties
1 On the contrary, the essentially practical sciences, that is to say the
arts, themselves apply their rules to particular cases. These sciences
are, strictly speaking, practical, but are not sciences in the strict sense
but only improperly.
There are thus many degrees of practicality. The philosophy of art
(whose end is practical, and whose object an operabile, but to be known)
provides no rules immediately applicable to particular cases. It is
only improperly and very imperfectly practical.
Ethics (whose end is practical, and whose object is also an operabile,
but also to be known) does not apply, but provides rules immediately
applicable to particular cases. It is as practical as a science in the

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arising from our passions and the complexity of
material circumstances.
It remains, therefore,
essentially speculative in its final object {knowledge
of human acts) and in its procedure (the deduction of
truths from their premisses, not incitement to action)
and is thus practical only in an improper sense.1 If
man is to do the right in the order of action moral
science must be supplemented by the virtue of
prudence, which, if we make use of it, makes us always
judge correctly of the act we should perform, and will
always that which we have thus judged to be right.
On the other hand, ethics only supplies rules of
human conduct in the natural order and in relation
to man’s last end as it would be, if it were a natural
happiness. But since, in fact, man’s last end is a
supernatural good {God possessed not by the imperfect
knowledge of human reason as such, but by the
strict sense can be practical, but it is not strictly speaking or perfectly
practical.
The arts—medicine, for example, or engineering—whose object is
something to be done (not merely an operabile, but envisaged operabiliter), provide rules immediately applicable and actually apply
them to particular cases, but only by enabling us to judge of what is
to be done, not by making us will to do it (for the artist can make a
mistake and still be an artist (because he wills to make it). They are
in the strict sense practical—but do not attain the highest degree of
practicability.
Finally prudence (whose object is also something to be done) applies
to particular cases the rules of moral science and reason, not only
teaching us to judge of the act to be performed, but making us employ
as we ought our free activity (for the prudent man, as such, always wills
the right). It is, strictly speaking, practical, and attains the highest
degree of practicability.
1 Cf. St. Thomas, Sup. Boet. de Trin., q. 5, a. 1, ad 3 : Scientia moralis,
quamvis sit propter operationem, tamen illa operatio non est actus scientiae, sed
actus virtutis, ut patet V Ethic. Unde non potest dici ars, sed magis in illis
operationibus se habet virtus loco artis et ideo veteres diffinierunt virtutem esse
artem bene recteque vivendi, ut dicit August. X, de Civ. Dei.

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beatific and deifying vision of the Divine Essence'), and since
his actions must be regulated in reference to this
supernatural end and so as to enable him to attain it,
ethics or philosophic morality is evidently inadequate
to teach him everything he needs to know in order to
act rightly. It must be completed and elevated by
the teachings of revelation.
The epithet practical, applied to ethics, does not
merely mean having as its aim an activity other than that
of simply knowing (in this sense practical, whether used of
art or morals, is opposed to speculative) ; but more
strictly concerned with action and behaviour (the
rcpaxTÓv, the distinctive sphere of moral science and the
moral virtues as contrasted with the 7roi7)T0v, the
distinctive sphere of art).

The fundamental question which practical philosophy
must answer before any other is in what consists
(from the standpoint of the natural order) the last
end or absolute good of man. It must then study
the actions by which man approaches or departs
from his last end, examining first their nature and
inner machinery, then what constitutes their moral
character, that is to say, renders them morally good
or bad. Ethics must, therefore, study in themselves
the supreme rule of such actions (questions which
treat of the eternal law and the natural law) and their
immediate rule (questions relating to the conscience);
it must also study the intrinsic principles from which those
acts proceed, that is to say, the moral virtues and vices.
But since ethics is a practical science it must not
be content with these universal considerations ; it
must proceed to the more particular determination of
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human acts and their rules. It is therefore obliged to
study in great detail the rules which regulate man’s
conduct first so far as they concern the good of the agent
himself and secondly so far as they concern the good
of others (consequently the virtue of justice).
The latter inquiry introduces a number of most
important questions pertaining to what is called
natural right, and treating in the first place of man’s
obligations to God (a question of natural religion),1
secondly of his obligations to his fellow-men. Here
are discussed the questions which concern men as
individuals (the rights of the individual, for example,
the right of property), and those which concern them as
members of a natural whole whose common good
individuals must serve—the family and the political
society (the rights of society).
Aristotle divided the science of morality, of human
conduct {ethics in the wide sense) into three parts :
the science of man’s actions as an individual, ethics
(in the stricter sense) ; the science of his actions as
a member of the domestic society, economics ; the
science of his actions as a member of the city (the civil
society), politics.2

On the fundamental question of ethics—the question
of man’s last end—we find for the last time the schools
of philosophy divided roughly into three groups.
The school of Aristotle and St. Thomas teaches that
the entire moral fife depends on man’s tendency to
his sovereign good or happiness and that the object
1 I.e. of religion as it would be apart from the supernatural order
to which man has in fact been raised.
2 See on this point Nic. Eth., vi, 9, 114? a 9 ; End. Eth., i, 8, 1218
b I g, and the two first chapters of the Politics. Cf. Hamelin, op. cit., p. 85.

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in which this happiness consists is God—whom, more­
over, we ought to love, not for our own sake, but for
himself (precisely because he is our last end, that
is to say, that which is willed and loved for itself, not
for the sake of anything beyond).
The schools which find the end and rule of human
conduct in pleasure {hedonism, Aristippus, Epicurus),
utility {utilitarianism, Bentham, John Stuart Mill), the
state (Hegel and sociologists'), humanity (Auguste Comte),
progress (Herbert Spencer), sympathy (the Scottish
school), pity (Schopenhauer) or the production of the
superman (Nietzsche), assign as man’s last end some­
thing created, and thereby degrade him below himself.
The schools which claim that virtue (the Stoics,
Spinoza) or duty (Kant) is self-sufficient, either because
virtue is itself happiness, or because the pursuit of
happiness is immoral, assign as man’s last end man
himself, and thereby, while seeming to deify man,
really, like the schools last mentioned, degrade him
below himself, for the greatness of man consists in
the fact that his sole end is the uncreated Good.
Thomist Philosophy
{Ethics of Happiness or the Sovereign Good)
Man is ordered to a last end other than himself, and
this last end is God.
Moral Systems which degrade
Man
Man is ordered to a last
end other than himself,
and this end is something
created {hedonism, Epicure­
anism, utilitarianism, etc.).

Moral Systems which deify
Man
Man is not ordered to
any last end other than
himself, his own virtue
being his last end {Stoicism),
or his goodness not de­
pending on any good for
which he has been made
{Kantism).

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Thus on every one of the great problems of
philosophy the doctrine of Aristotle and St. Thomas,
when compared with the doctrines of other
philosophers, appears as an eminence between two
contrary errors. This is an additional argument for
its truth to be added to those enumerated earlier.1
The truth, indeed, is not to be found in a philosophy
which keeps the mean between contrary errors by its
mediocrity and by falling below them, being built up
by borrowing from both, balancing one against another
and mingling them by arbitrary choices made without
the light of a guiding principle {eclecticism) ; it must be
sought in a philosophy which keeps the mean between
contrary errors by its superiority, dominating both, so
that they appear as fragments fallen and severed from
its unity. For it is clear that, if this philosophy be
true, it must reveal in full what error sees only in part
and distorted by a bias, and thus must judge and
secure, by its own principles, and in the light of its
own truth, whatever truth error contains though it
cannot distinguish.
1 See pp. 99-101.

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Philosophy is thus divided into three principal
sections : logic, speculative philosophy, practical philosophy ;
or, if we take account of the subdivisions of these three
sections, into seven main sections : minor logic, major
logic; the philosophy of mathematics, the philosophy of
nature, metaphysics ; the philosophy of art and ethics.
This order is represented by the following table :
í I. Minor or formal logic : the rules of reasoning
( 2. Major or material logic : the matter of reasoning
'3. The philosophy of mathematics : quantity
I
,
.... h, f ,
(the material world f^logy
II
4. 1 he philosophy of nature : {
(man
psychology
SPECULATIVE.
i truth
(epistemology) criticism
PHILOSOPHY
5. Metaphysics -! being in general
ontology
.
I being a se
(natural theology) theodicy

I

logic

III

Í6. The philosophy of art : making

practical -i
philosophy ( 7.

Ethics or moral philosophy : action, conduct

The division of philosophy into speculative and
practical depends, not on the specific character of the
various philosophic sciences, but on the end which they
pursue. If that end is knowledge alone, the philosophy
is speculative ; if the good of man, it is practical.1
If the philosophic sciences are classified from the
standpoint of their specific character,2 ethics, which
1 See St. Thomas, Sup. Boet. de Trin., q. 5, ad 4.
2 This specification depends essentially on the degree of abstraction
or degree of immateriality of the object studied.

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treats of the moral virtues 1 and whose formal object
is human action, and the philosophy of art, which treats
of the practical intellectual virtues and whose formal
object is human making, are divisions of the science of
man, which itself belongs to natural philosophy (though
it enters also into metaphysics}.
From this point
of view we can recognise as specifically distinct
philosophic sciences only logic, metaphysics, and the
philosophy of nature, also the philosophy of mathematics, if
this is not regarded as a subdivision of metaphysics or
of the philosophy of nature.
1 Sic pertinet ad philosophiam (naturalem), et est pars illius, quia agit de
anima ut est actus corporis, et consequenter de moralibus ejus. (John of
St. Thomas, Cursus, phil., i, p. 732 ; Log., ii, q. 27, a. 1.)

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