Super Boethium De Trinitate

Thomas Aquinas

Questions 1-4, translated by Rose E. Brennan, S.H.N. (Herder, 1946)
Questions 5-6, translated by Armand Mauer (Toronto, 1953)



St. Thomas' Commentary

QUESTION I: Concerning the knowledge of divine things

  1. Whether the Human Mind in Order to Attain to a Knowledge of Truth Requires a New Illumination of Divine Light
  2. Whether the Human Mind Can Arrive at an Idea of God
  3. Whether God Is the First Object Known by the Mind
  4. Whether the Human Mind Is Capable of Arriving at a Knowledge of the Divine Trinity Through Natural Reason
QUESTION II: Concerning the manifestation of knowledge of divine truth
  1. Whether Divine Truths Ought to Be Treated of by the Method of Inquiry
  2. Whether There Can Be Any Science of Divine Truths Which Are Matters of Faith
  3. Whether in the Science of Faith, Which Is Concerning God, it Is Permissible to Use the Rational Arguments of the Natural Philosophers
  4. Whether Divine Truths Ought to Be Concealed by New and Obscure Words
  1. Boethius' Text
  2. St. Thomas' Commentary
QUESTION III: Concerning Those Things That Pertain to the Knowledge Possessed by Faith
  1. Whether Faith Is Necessary for Mankind
  2. Whether Faith Should Be Distinguished from Religion
  3. Whether the Christian Religion Is Aptly Called Catholic or Universal
  4. Whether it Is a True Article of Faith, That the Father, Son, and Holy Spirit Are One God
QUESTION IV: Concerning Those Things That Pertain to the Cause of Plurality
  1. Whether Otherness Is the Cause of Plurality
  2. Whether Variety of Accidents Produces Diversity According to Number
  3. Whether Two Bodies Can Be, or Can Be Conceived of as Being Simultaneously in the Same Place
  4. Whether Variety of Location Has Any Influence in Effecting Numerical Difference
  1. Boethius' Text
  2. St. Thomas' Commentary
QUESTION FIVE: The division of speculative science
  1. Is Speculative Science Appropriately Divided into these Three Parts: Natural, Mathematical, and Divine?
  2. Does Natural Philosophy Treat of What Exists in Motion and Matter?
  3. Does Mathematics Treat, Without Motion and Matter, of What Exists in Matter?
  4. Does Divine Science Treat of What Exists Without Matter and Motion?
QUESTION SIX: The methods of speculative science
  1. Must we Proceed according to the Mode of Reason in Natural Science, according to the Mode of Learning in Mathematics, and according to the Mode of Intellect in Divine Science?
  2. Should We Entirely Abandon the Imagination in Divine Science?
  3. Can Our Intellect Behold the Divine Form Itself?
  4. Can Our Intellect Behold the Divine Form by Means of Some Speculative Science?


“I will seek her out from the beginning of her birth, and bring the knowledge of her to light” (Wis. 6:24)

The natural intuition of the human mind, burdened by the weight of a corruptible body, cannot fix its gaze in the prime light of First Truth, in which all things are easily knowable; whence it must be that, according to the progress of its natural manner of cognition, the reason advances from the things that are posterior to those that are prior, and from creatures to God. “For the invisible things of Him, from the creation of the world, are clearly seen, being understood by the things that are made” (Rom. 1:20) and “For by the greatness of the beauty and of the creature, the Creator of them may be seen, so as to be known thereby” (Wis. 13:5); and this is what is said in Job 36:25: “All men see Him, gazing from afar.”

For creatures, through whom God can be known by the natural light of reason, are at an infinite distance from Him. But since, in those who look at a thing from a great distance, vision may readily be deceived, therefore those striving to attain to a knowledge of God from creatures fell into many errors: wherefore it is said: “The creatures of God are... a snare to the feet of the unwise” (Wis. 14: 11), and: “They have failed in their search” (Ps. 63:7); and therefore God has provided for the human race another safe road of cognition, bestowing upon the minds of men, by faith, a knowledge of Himself. Therefore, it is said: “The things also that are of God no man knows, but the Spirit of God: but to us God has revealed them by His Spirit” (1 Cor. 2: 11): and this is the Spirit by whom we are enabled to be believers: “Having the same spirit of faith, as it is written: ‘I believed, for which cause I have spoken’ (Ps. 115: 10); we also believe, for which cause we speak also” (2 Cor, 4:13)

Therefore, as the principle of our cognition is naturally the knowledge of created things, obtained by means of the senses, so the principle of supernatural cognition is that knowledge of First Truth conferred upon us, infused by faith; and hence it follows that in advancing one proceeds according to a diverse order. For philosophers, who follow along the way of natural cognition, place knowledge about created things before knowledge about divine things: natural science before metaphysics: but among theologians the procedure is in reverse order, so that study of the Creator comes before that of creatures.

This order, therefore, Boethius followed: intending to treat of those things which are of faith, he took as the starting point of his study that highest origin of things, namely, the Trinity of the one, simple God. Whence it is that the above-quoted words are applicable to him: “I will seek her out from the beginning of her birth, and bring the knowledge of her to light.”

In these words, as regards the present opusculum, which he addressed to Symmachus, a patrician of Rome, three things can be noted: namely, the matter, the mode, and the purpose.

The matter of this work is the Trinity of Persons in the one, divine Essence, that Trinity which has its source in the primal nativity in which divine wisdom is eternally generated by the Father. “The depths were not as yet, and I was already conceived” (Prov. 8:24), and: “This day have I begotten you” (Ps. 2:7)

This nativity is the beginning of every other nativity, as it is the only one involving perfect participation in the nature of the generator: but all others are imperfect according as the one generated receives either a part of the substance of the generator, or only a similitude: from this it follows that from the aforesaid nativity, every other is derived by a kind of imitation; and thus: “Of whom all paternity in heaven and in earth is named” (Eph. 3: 15); and on this account the Son,is called the first-born of every creature (Col. 1:15) so that the origin of nativity and its imitation might be designated, but not according to the same meaning of generation; and therefore it is aptly said: “I will seek her out from the beginning of her birth.” “The Lord possessed me in the beginning of his ways” (Prov. 8:22); for not only of creatures is the aforesaid nativity the beginning, but even of the Holy Spirit, who proceeds from the Generator and the Generated.

But in saying this, he does not say: “I will seek out the beginning of nativity,” but “from the beginning” signifies that his search is not limited by initiation of this kind of nativity, but that, beginning from this, he proceeds to others, for his doctrine is divided into three parts. The first part, concerning the Trinity of Persons, from the procession of whom every other nativity and procession are derived, is contained in that book which we possess at hand, so far as anything can be known about the Trinity and Unity.

But in another book which he wrote to John, a deacon of the Roman Church, we find what he says about the mode of predication which we employ in the distinction of Persons and unity of essence; and this book begins: “I inquire whether the Father.”

The second part, which is about the procession of good creatures from a good God, is in a book that is written to the same John (De hebdomadibus), and this begins: “You ask of me.

The third part is about the separation of creatures through Christ. This is divided into two parts: For first, there is set forth the faith which Christ taught by which we are justified, in that book entitled De fide Christiana, which begins: “The Christian faith.” In the second part, an explanation is given of what must be held about Christ: namely, how two natures are united in one person. This discussion of the two natures and the one person in Christ is also in a book written to the same John, which begins: “You, indeed, solicitously.”

Now the mode employed in treating of the Trinity is twofold, as St. Augustine says in I De Trinitate, namely, through truths known on the basis of authority, and through those known by reason, both of which modes Augustine combined, as he himself says.

Some of the holy Fathers, as Ambrose and Hilary, employed but one mode of explanation: namely, by setting forth those truths founded upon authority. But Boethius chose to proceed according to the other mode; namely, according to reasoned arguments, presupposing what had been concluded by others on the grounds of authority. Hence also the method of his work is indicated in what he says: “I shall investigate”, in which an inquiry of reason is signified. In Sirach 39:1 we read: “Wisdom,” namely, knowledge of the Trinity; “of all the ancients,” that is, which the ancients affirmed solely on the grounds of authority; “the wise man will seek out,” that is, he will investigate by reason.

Wherefore, in the preface he speaks of “An investigation carried on for a very long time.”

The purpose of this work is: that hidden things may be made manifest, so far as that is possible in this life.

“They that explain me shall have life everlasting” (Sirach 24:31); and therefore, he says: “I will bring the knowledge of her to light” (Wis. 6:24). “The depths also of rivers he searched, and hidden things he brought forth to light” (Job 2 8: 11).


The problem which has been for so long a time the subject of my investigation—to the extent that the divine light has deigned to enkindle the feeble spark of my mind—now arranged according to a reasoned plan and consigned to writing, I have taken pains to offer and share with you, prompted as much by desire for your judgment as by zeal for my task.

In this matter it is possible to understand what my intention is whenever I entrust my thought to pen, both because of the difficulty of the matter and because it is only to you men that I am addressing it.

Indeed, I am not prompted by any desire for fame or for empty popular applause; but if there is any exterior reward, it can be no other than to hope for a judgment in keeping with the matter.

For, wherever I have directed my gaze, apart from you, I have encountered, on the one side, stolid indifference or, on the other, sly envy, so that I would appear to offer insult to matters pertaining to divine things by putting them before such monsters of men to be trampled under foot by them rather than to be acknowledged. On this account I restrain my pen by brevity, and truths gleaned from the deepest teachings of philosophy I veil over by the signification of new words, so that they may speak only to me and to you; if you, indeed, will direct your attention to them. But, as for others, I so disregard them that those who are unable to grasp the meaning of my words shall seem unworthy to read them.

Only so much ought one require of me as the intuition of human reason can approximate about the sublime truths of the Godhead. For in the case of other arts, the same limit is also established, namely, that which by the way of reason one can attain. Now, medicine does not always effect the cure of the patient. But no blame will be placed upon the physician if he has omitted none of the things which he ought to have done; and the same is true in other matters.

Moreover, in proportion to the difficulty of a problem, the pardoning of error ought to be the more easily granted. You must also determine this: whether the seeds of speculation, gathered from the writings of the blessed Augustine, have in my work borne fruit.

Now, therefore, let us undertake at this point the discussion of the proposed question.

St. Thomas’ Commentary

To this work the author prefixes a preface, in which he does three things: First, he briefly indicates the causes of the work, in doing which he inclines his hearer to accept what he says. Secondly, he adds an excuse or explanation in which he gains the good will of his hearer, where he says: “I restrain my pen.” In the third place, he points out that the source of his work and, in a certain way, its teaching, is the doctrine of St. Augustine, and in doing this he renders his hearer attentive, when he says: “You must also determine this: whether the seeds of speculation, gathered from the writings of blessed Augustine, have in my work borne fruit.”

He likewise sets forth in the first part the four causes of his work.

1) First, the material cause, when he says: “the problem which has been for so long a time the subject of my investigation,” that is, about the Trinity of Persons of the one God; and in these words he implies both the difficulty of the matter, because he has carried on the investigation for a very long time, and also the diligence of the study with which he has for so long a period investigated it, as “investigation” is understood by us, although it can also be understood to mean investigation by many; because from the beginning of the existence of the Church, this question has especially continued to challenge the cleverest minds of Christians.

2) Secondly, he indicates the proximate or secondary efficient cause when he says: “the feeble spark of my mind.” Moreover, he speaks also of the first or principal cause when he adds: “that the divine light has deigned to enkindle.”

Now the proximate cause of this investigation is, indeed, the intellect of the author, which is rightly termed a spark. “For fire,” as Dionysius says (XV Coel. hier.), “especially serves to signify properties of the divinity: at once by reason of its subtlety, of its light, and also by reason of its place and motion.”

These things, in the highest degree, pertain to God, in whom exist the culmination of simplicity and of immateriality, perfect charity, almighty power, and highest majesty.

To the angels, “fire” (as indicative of intellect) may be applied in a middle sense, but to human minds, with only a more restricted meaning; for by union with a body, its purity is lessened, its light is obscured, its power weakened, and its upward motion retarded: wherefore the efficacy of the human mind is rightly compared to a spark.

Hence it would not be able to investigate the truth of this question unless light were cast upon it by the divine light; and thus the divine light is the principal cause; but the human mind, a cause in the secondary order.

3) Thirdly, he treats of the formal cause when he says: “arranged according to a reasoned plan,” and he indicates the mode of treatment under three headings.

a) First, since he proceeds by argumentation, he therefore says, “arranged according to a reasoned plan.” For a question discussed even over a long period according to probable reasons but still with doubt is, as it were, without form, not yet laying claim to the certitude of truth; and hence it is said to possess form when reasonable proof is added, through which certitude regarding the truth may be attained: in this process, intellect gives us vision of the truth, because what we believe, we owe to authority; but what we understand, we owe to reason, as Augustine says.

b) In the second place he discusses the mode of treatment, since he treats of this matter not only in words, but has incorporated it in writing, he says: “I entrust my thought to pen.” In so doing, he has made provision against the weaknesses of memory.

c) Thirdly, since he has written, not after the manner of one imparting doctrine to another present with him, but as to one absent, by means of a letter.

Thus Aristotle also composed his books in different ways: some addressed to those who in his presence listened to him, and these books are called Auditus, as one such book is, entitled, De naturali auditu; but certain others he wrote to those absent, as we find in I Ethic. that the books De anima were so written, where the names of discourses addressed to those at a distance are given, as the Greek commentator says.

Accordingly, he adds: “I have taken pains to offer and share with you, prompted by desire for your judgment,” as if addressing an expert and asking his opinion in this matter. Thus, he continues: “prompted as much by desire for your judgment as by zeal for my task.” Because he had been zealous for ascertaining the truth, he had ordered the aforesaid question according to reasonable arguments; and, because he was desirous of the judgment of Symmachus, he presented to him the work thus arranged in orderly fashion.

4) In the fourth place, he refers to the final cause when he says: “What my intention is,” that is, what end I am striving for in regard to the above-mentioned problem: “Whenever I entrust my thought to pen” concerning the aforesaid or certain other matters, “it is possible to understand” for two reasons: “because of the difficulty of the matter” and also, “because it is only to you men that I am addressing it.”

This book, therefore, he has not written in order to read it to the many, which would be with hope of popular acclaim, but rather, for one wise man alone; wherefore, he continues: “I am not prompted by any desire for fame or for empty popular applause,” as are the poets who recite their verses before the foolish crowds in the theater, because such applause is often altogether without reason. Thus he puts aside any unworthy end and establishes one that is honorable, implying a principal purpose, which is interior, namely, knowledge of divine truth, and, explicitly pointing out a secondary end, that is, the judgment of a wise man, when he says: “If there is any exterior reward,” as if he would say: It is an interior reward that principally urges me on, but if there is any that is exterior, this can be none other than to wait and to hope for a judgment like to the matter, that is, proportionate to it: By way of exterior return I ask for nothing except what is fitting in a matter of such importance, in regard to which I have stated that a judgment of it should be neither stolidly indifferent nor the bitter one of an envious critic, but only that pronounced in good will by a wise man. Accordingly, he adds: “Wherever I have directed my gaze apart from you, that is, to whomsoever I have looked, except to you alone, I have encountered on the one side, stolid indifference”; that is, lack of comprehension, “on the other side, sly envy,” that is, ill will, sly only in condemnation, so that he who treated of these things, would seem to offer insult to divine treatises, that is, by inordinately explaining them “to such monsters of men.” Men are called monsters who, though in human body, bear within them the heart of a beast, since vice has made them like to beasts in their affections; hence these things “would be trampled under foot by them, rather than acknowledged,” because they do not so much seek to know, but—because of their envy—to revile whatever is said; wherefore, “Give not what is holy to dogs, neither cast your pearls before swine, lest they trample them under their feet” (Matt. 7:6). Therefore, that I should not do otherwise than this, “I restrain my pen by brevity.”

This is the second part of the preface, in which he adds an explanation of his manner of writing. And first, he explains the difficulty of the task. In the second place, he excuses its imperfection. “Only so much ought one require of me as the intuition of human reason can approximate about the sublime truths of the Godhead. He refers also to a threefold difficulty which purposely he attached to it.

The first is by reason of the brevity of his writing; wherefore, he says, “I restrain my pen by brevity,” according to that saying of Horace: “While I labor to be brief, I become obscure.”

The second arises from the subtlety of the reasoning which he introduces; thus he says: “truths gleaned from the deepest teachings of philosophy,” which are those doctrines abstracted from the senses, the principles and conclusions which metaphysics and logic make use of.

The third difficulty arises from the newness of the words used; wherefore he says: “I veil over by the signification of new words.” These words are called “new” either with reference to the matter, because others treating of this same question did not employ the same vocabulary, or with reference to those who read them, because they are unaccustomed to such terms.

These three difficulties he adds to the fourth which he had previously mentioned: that is, the difficulty of the subject; consequently, in regard to those things written in this book, the meaning is clear only to the wise, to such men as the author himself and the one to whom he has addressed it. But others who cannot comprehend it are excluded from the reading of it. For things which are not understood are not read with pleasure. And because his reason for so writing is connected with preceding statements, he introduces it ‘with “therefore,” which is a sign of a conclusion. The meaning is clear.

“Only so much ought one require of me as the intuition of human reason can approximate about the sublime truths of the Godhead.” Here he excuses a defect of the work, because, indeed, one ought not demand from him in this task any more certitude than that which the human reason, in mounting up to the divine, is capable of; a position which he justifies by reference to matters of less importance in other arts, in which only such an end is established for each craftsman as he can accomplish, one such as human reason allows. A physician does not always, indeed, effect a cure, but if he omits nothing which he ought to do, he will be without blame; and the same is true in regard to other arts. Therefore in this work, where the matter is difficult, going beyond the experience of human nature, the greater leniency ought to be granted if he does not solve the question with perfect certitude.

Then, when he says: “You must also determine this: whether the seeds of speculation, gathered from the writings of the blessed Augustine, have in my work borne fruit,” he adduces whose authority he follows in his work, namely, Augustine. Not that he says only those things that are to be found in the books of Augustine, but because those things which Augustine said regarding the Trinity—namely, that the divine Persons are equal in an absolute sense and are distinguished according to relationships—he accepts as seeds and principles, which he uses in resolving this difficult question; and so this explanation of truth by means of many considerations of reason is the fruit springing forth from those seeds found in the writings of Augustine himself; but whether they are acceptable and productive, he leaves to the judgment of him to whom he writes, thus coming directly to the proposed question.


Concerning the Knowledge of Divine Things

Here there occurs a twofold question: concerning the knowledge of divine things, and concerning the manifestation of them.

In regard to the first, four things are asked:

1. Whether the human mind in order to attain to a knowledge of truth requires a new illumination of divine light.

2. Whether it can attain to an idea of God.

3. Whether God is the first object known by the mind.

4. Whether the human mind is capable of arriving at a knowledge of the divine Trinity by natural reason.

Article 1

Whether the Human Mind in Order to Attain to a Knowledge of Truth Requires a New Illumination of Divine Light


1. It seems that the human mind in attaining to any knowledge whatever requires a new illumination of divine light. “Not that we are sufficient to think anything of ourselves as of ourselves, but our sufficiency is from God” (2 Cor 3:5); but there can be no perception of truth of any kind whatever without thought; therefore the human mind cannot know any truth unless it is illuminated by a new light from God,

2. It is easier to learn any truth from another than to discover it for oneself: wherefore, those who know things by their own efforts are preferred to those who are able to learn from other men, according to I Ethic.; but man is not able to learn from another unless his mind is interiorly taught by God, as Augustine says in his book, De magistro, and Gregory in Hom. Pentec.; therefore neither can anyone discover truth of himself unless his mind is illuminated by God with a new light.

3. As the eyes of the body are related to corporeal things which they behold, so is the intellect related to the intelligible truth which it perceives, as is evident in III De anima; but the bodily eye cannot see corporeal things unless it is illuminated by the material sun; therefore neither can the intellect behold the truth unless it is illuminated by the light of the invisible sun, which is God.

4. Those acts are said to be in us (as our own) for the exercise of which we possess within ourselves principles that are sufficient; but in us there is not the power to know truth altogether [or absolutely] for there are many who labor to learn the truth and who, nevertheless, are unable to do so; therefore we have not in us sufficient principles for knowing truth and so it must be that to arrive at knowledge of it we require aid from outside ourselves, and so the conclusion is like the foregoing.

5. The operation of the human mind depends more upon the divine light than does the operation of sensible or inferior beings upon the light of the material heaven; but inferior bodies, although they have forms which are principles of their natural operations, are, nevertheless, incapable of perfecting these operations unless they are aided by the influence of the light of the stars; wherefore Dionysius (De div. nom., chap. 4) says that the light of the sun contributes to the generation of visible bodies and that it moves them to life and nourishes them and causes them to grow; therefore its natural light, which is, as it were, its form, would not, suffice to make truth visible to the human mind unless another light, namely, the divine, supervened to assist it.

6. In all causes that are ordered to one another essentially, and not accidentally, no effect proceeds from a second cause unless through the operation of a first cause, as is established. in the first proposition of De causis; but the human mind is ordained beneath the uncreated light according to an order that is essential and not accidental; therefore the operation of the human mind which is its proper effect, namely, the cognition of truth, cannot proceed from it unless by reason of the operation of the first uncreated light: its operation, however, seems to indicate nothing other than illumination; therefore, etc.

7. As the will is related to willing well, so the intellect is related to right understanding: but the will cannot will well unless it is aided by divine grace, as Augustine says; therefore neither can the intellect know the truth unless illuminated by divine light.

8. That for which our powers do not suffice is wrongly ascribed to our strength: but it is reprehensible that anyone should ascribe knowledge of the truth to his own ability, since indeed we are even commanded to ascribe it to God, according to this saying of Sirach 51:23: “To Him that giveth me wisdom, will I give glory”; therefore our powers do not suffice for knowledge of truth, and so the conclusion is as before.

Sed contra. The human mind is divinely illuminated by its natural light, according to the saying of Psalm 4:7: “The light of Your countenance, O Lord, is signed upon us.” Thus, therefore, if this created light is not sufficient for the knowing of truth, but there is required a new illumination, according to the same reasoning this superadded light would not suffice either, but wiluld require still another light, and so on to infinity, which cannot be encompassed; and so it would be impossible to know any truth. Therefore one must stand firm in reliance upon the first light, namely, that the mind by its natural light, without the superaddition of any other, can see the truth.

Again, as it suffices for what is actually visible that it should he proportionate to the sight in order to move it, so it suffices for what is intelligible that it should be proportionate to the intellect in order to move it: but our mind possesses within itself the power of making things intelligible in act, namely, the active intellect, and what is intelligible is proportionate to it; therefore it does not require another new illumination in order to know truth.

Moreover, as corporeal light is related to bodily vision, so is the intellect related to intelligible vision. But any corporeal light at all, even though it is weak, renders something corporeally visible, at least itself; therefore, the light of the intellect also, which is connatural to the mind, suffices for the understanding of some truth.

Furthermore, all things that are artificially made depend upon the cognition of some truth since the principle of them is knowledge; but it is certain that products of art do exist in which, according to Augustine, the free will is able [to act] by itself, as in building houses and the like; therefore man is sufficiently capable of knowing some truth without a new divine illumination.

Response. It must be said that between potencies that are active and those that are passive there is this difference: passive potencies cannot enter on the act of their proper operation unless they are moved to do so by their own active agents, just as the senses experience no sensation unless moved by some sensible object; but active potencies are capable of operation without being moved by another, as is evident in the case of the potencies of the vegetative soul: but as regards the intellect, a twofold potency is found, an active potency, that is, the active intellect, and a passive potency, that is, the possible intellect.

Now, there are certain philosophers who maintained that the possible intellect alone is a faculty of the soul, while the active intellect is a separate substance; and this is the opinion of Avicenna. According to this opinion, it follows that the human soul would not be capable of entering upon its proper operation, which is knowledge, unless illuminated by an exterior light, namely, by the light of that separate substance which they call the active intellect.

But because the words of the Philosopher (III De anima) seem to proclaim more convincingly that the active intellect is a potency belonging to the soul—and with this the authority of Scripture agrees, which declares that we are distinguished by that intellectual light to which the Philosopher compares the active intellect—therefore it is held that there is in the soul, fitting it for intelligible operation, that is, for undertaking the cognition of truth, a potency which is active and another which is passive. Wherefore, as some powers which are naturally active, when conjoined with those which are their passive complements, suffice for the carrying on of their natural operations, so also the soul of man, having in itself an active and a passive potency, is sufficient for perception of the truth.

Since, however, the power of any created thing is but finite, its efficacy will be limited to certain determined effects. Consequently it cannot attain to certain other effects unless new power is added to it; but there are some intelligible truths to which the efficacy of the active intellect does extend, as, for example, those first principles which man naturally knows, and those truths which are deduced from them; and for such knowledge no new light of intelligence is required, but the light with which the mind is naturally endowed suffices.

But there are other truths to which the aforesaid first principles do not extend; e.g., the truths of faith and things that exceed the faculty of reason, such as knowledge of future contingent events, and the like; and such things the human mind cannot know unless it is divinely illuminated by a new light, superadded to that which it naturally possesses.

For, although it does not require the addition of new light for knowledge of those things to which reason naturally extends, it does require divine operation: for over and above that operation by which God created the natures of thingsgiving to each its proper form and ability, by which they are able to exercise their proper operation. He also operates in things the works of Providence, directing and moving the capabilities of all things to their proper acts. For in this way the whole universe of creatures is subject to the divine governance, as instruments are subject to the direction of the workman and as natural qualities are subject to the power of the nutritive soul, as is said in II De anima. Therefore, as the work of digestion is accompanied by a natural heat, according to the measure which the digestive function imposes upon heat, and as all the inferior powers of the body operate according as they are directed and moved by virtue of the heavenly bodies, so all the active created powers are governed and moved by the Creator.

Thus, therefore, in all cognition of truth, the human mind requires the divine operation. In the realm of naturally known truths, however, it requires no new light, but only the divine motion and direction; for the knowledge of other (supernatural) truths it needs also a new illumination. And because it is of such things that Boethius speaks, he says: “To the extent that the divine light has deigned to enkindle the feeble spark of my mind.”

Answers to objections.

1. Although we are in no way sufficient of ourselves, as from ourselves, to know anything without the operation of God, yet it is not necessary that for every operation of ours a new light should be given to us.

2. In matters of natural cognition God teaches us interiorly in this way: that He is the cause of the natural light which is in us, and He directs it to the truth; but in other (supernatural) matters He further teaches us by the infusion of a new light.

3. The eye of the body, when illuminated by the light of the material sun, does not respond to a light which is in any way natural (i.e., intrinsic) to itself, by means of which it makes things to be actually visible; even as is the case with the mind when it is illuminated by the uncreated Light; and therefore the eye always requires an exterior light, but not the mind.

4. Where there is pure light of intellect, as in the angels, it makes,evident without difficulty all things known in the natural order, so that in them there is cognition of all objects naturally intelligible to them: in us, however, this light is obscure, being overshadowed as it were by reason of conjunction with the body and with corporeal powers, and on this account it ii hindered so that it cannot freely and naturally behold that truth which is itself knowable, as is said in the Book of Wisdom (9:15): “For the corruptible body is a load upon the soul; and the earthly habitation presseth down the mind that museth upon many things.” From this it follows that on account of the impediment (of the body) it is not in our power to know truth altogether in its fullness. But each one possesses more or less the power to know in proportion to the purity of the intellectual light which is in him.

5. Although inferior bodies have need of superior bodies for their operation, to the extent that they must be moved by them; nevertheless, for the perfect accomplishment of their proper functions, they do not need to receive from these superior bodies any new forms, And in like manner it is not necessary that the human mind, which is moved by God, should be endowed with any new light in order to understand those things which are within its natural field of knowledge.

6. As Augustine says (VIII Super Gen. ad litteram), as the air is illuminated by the presence of light, but straightway grows dark if the light should be removed, so the mind is illuminated by God, and so also it is God who continually causes the natural light in the soul, not one kind now and another kind at another time, but the same (natural light); for He is the cause not only of its coming to be, but of its continued existence in us. In this way, therefore, God continually operates in the mind since He causes and governs the natural light in it, and thus the mind does not carry on its own function without the operation of the First Cause.

7. The will never can will the good without divine incitement: nevertheless it can will the good without infusion of grace, though not meritoriously. And likewise the intellect, without divine influence, is incapable of knowing any truth whatever; it can, however, know without infusion of new light, though not those truths which exceed natural cognition.

8. From the very fact that God causes the natural light in us by conserving it and directing it to seeing, it is manifest that perception of the truth must be ascribed principally to Him, just as the producing of a work of art is ascribed to the artist rather than to the thing produced.

Article 2

Whether the Human Mind Can Arrive at an Idea of God


1. It seems that in no way can God be known,by us. For that which in the highest degree of our knowledge remains unknown to us, in no manner is knowable: but in the most perfect degree of our cognition we are not united with God, except as with One who is, as it were, unknown, as Dionysius says (Theologia mystica, chap. 1); therefore God is in no way knowable by us.

2. Anything that is known is known through some other form; but, as Augustine says, God escapes (by transcending) every form of our intellect; therefore in no way is He knowable by us.

3. Between the knower and the thing known must be some kind of proportion, as in the case of any potency and its object; but between our intellect and God there can be no proportion, as there can be none between the infinite and the finite; therefore our intellect can in no way know God.

4. Since potency and act are reduced to the same genus, they divide all classes of being, no potency can be in act which is outside its own genus: just as the senses are incapable of knowing intelligible substance; but God is outside every genus; therefore He cannot be known by any intellect that is in a genus; but our intellect is of this kind.therefore, etc.

5. If that which stands first is done away with, everything consequent upon it is likewise put aside: but what is first intelligible about a thing is its quiddity; hence that which a thing is, is said to be the proper object of the intellect (III De anima); and what is serves as a medium of demonstrating whether it exists, and all the other conditions of the thing. But concerning God, we are unable to know what He is, as Damascene says. Therefore, we can know nothing of God.

Sed contra

But on the contrary is the saying of Rom. 1:20: “For the invisible things of Him, from the creation of the worla, are clearly seen, being understood by the things that are made: His eternal power also and divinity.”

According to Jer. 9:24: “But let him that glorieth glory in this, that he understandeth and knoweth Me”; but this would be empty glory unless we were able to know Him; therefore we can know God.

Nothing is loved unless it is known, as is evident from Augustine (II De Trinitate); but we are commanded to love God; therefore we are capable of knowing Him, since the impossible is not enjoined by precept.

Response. I answer: It must be said that there is a twofold way in which anything is known. One manner is through its proper form, as the eye sees a stone through the species of the stone. Another way is through some other form similar to it, as a cause is known through the similitude of its effect, just as man is known through the form of his image.

Moreover, through its own form a thing is also known in two ways. One way is the following: when knowledge is through the form which is the thing itself, as with God who eternally knows His own essence, and as an angel knows itself. According to another mode, knowledge is through a form which is other than the thing: either when the form has been abstracted from a thing—in which case the form is more immaterial than the thing itself, as is the form of a stone abstracted from the stone itself— or when the form is impressed on the intellect by a thing, as occurs when the thing is more immaterial than the similitude by which it is known; thus, as Avicenna says, we know intellectual beings through their impression in us.

Therefore, since our intellect has, in our present state of wayfaring, a determined relation to forms abstracted from sensible things (since it is dependent upon phantasms in the same way as sight is upon colors, as is said in III De anima), it cannot know God in this life through that form which is His essence; though it is in this way that He is known by the blessed in heaven.

No similitude, however, of whatever kind impressed by Him upon the human intellect, would suffice to make His essence known, since He infinitely transcends every created form; consequently God cannot be made accessible to the mind through created forms, as Augustine says. Nor, in this present state, can God become known to us even through the species of things which are purely intelligible, which have in a certain way a likeness to Him, because our intellect is connaturally related to phantasms, as has been said. Therefore it remains certain that it is only through the forms of His effects that He is known.

There are, moreover, two kinds of effects: those which adequate the power of a cause, and through such an effect the power of a cause is fully known, and consequently the essence of the cause; and another kind of effect which is not completely equal to its cause. Through this latter kind of effect it is not possible to comprehend the power of the agent, and consequently not its essence either; but regarding the cause it can be known only that it exists. Thus the knowledge of an effect stands as a principle whereby the existence of its cause is known, just as does the quiddity of the cause when it is known through its own form. Now, it is according to this second mode that every effect stands in relation to God; and hence we are not able in this life to attain to any knowledge of Him, except that He is.

Nevertheless, of those knowing that He is, one will know Him more perfectly than another, because a cause is more perfectly understood from its effect the more perfectly the relation of the cause to its effect is apprehended. And in this relation of an effect not reaching in equality to its cause, three things are noted: namely, the progression of the effect from its cause; secondly, the consequent similitude of the effect to its cause; and thirdly, the failure on the part of the effect to attairt to a perfect likeness of its cause. Thus the human mind grows in the knowledge of God, even though it cannot attain to a knowledge of what He is, but only to a knowledge that He is, in three ways.

Thus, in the first place, God is known as His productiveness and efficacy are more perfectly known. Secondly inasmuch as He is known as the Cause of the nobler of His effects, since ihose creatures which display being of a higher mode in their resemblance to Him manifest His eminence more than others. In the third place, He is better recognized as differenhated from all those things which appear in His effects.

Hence, in De divinis nominibus, Dionysius says that God is known inasmuch as He is the cause of all things, by His transcending eminence in comparison to all things, and by denial (of all created imperfection).

Moreover, in the attempt to arrive at some knowledge of God, the human mind is greatly assisted when its natural light is fortified by a new illumination: namely, the light of faith and that of the gifts of wisdom and of understanding, by which the mind is elevated above itself in contemplation, inasmuch as it knows God to be above anything which it naturally apprehends. But because even this new light does not suffice to penetrate to a vision of His essence, it is said to be, in a certain way, turned back upon itself by His excellent light; and this is what is said in Gregory’s gloss regarding the statement in Gen. 32:30 (“I have seen God face to face”): “When the vision of the soul is directed to God, it is reflected back upon itself, overwhelmed by the brilliance of His immensity.”

Answers to objections

1. It is answered: God as an unknown is said to be the terminus of our knowledge in the following respect: that the mind is found to be most perfectly in possession of knowledge of God when it is recognized that His essence is above everything that the mind is capable of apprehending in this life; and thus, although what He is remains unknown, yet it is known that He is.

2. It may be said: From the fact that the divine essence escapes any form of our intellect, evidently it is not possible to know what He is, but only that He exists.

3. It is answered: Proportion is nothing other than the mutual relation of two things associated by something in respect to which they either agree or differ. Now, agreement may be of two kinds.

In one way, things may be associated as belonging to the same genus of quantity or quality, as is the relation of one surface to another or of one number to another inasmuch as one excels the other or is equal to it, or even as heat is related to heat; and according to this mode of relation there is no possible proportion between God and creature, since there is no agreement in any genus.

In another way beings are said to be related when they are associated in a certain order; and in this way there is proportion between matter and form, between the maker and the thing made. This also is the kind of proportion required between knower and knowable, since what is knowable is, in a certain way, the act of the knowing power. Such, too, is the proportion of a creature to God: that of caused to its cause, and of knower to the knowable; but according as the excellence of the Creator transcends the creature, there is no proportion of the creature to the Creator which makes it possible to receive from Him an influx proportionate to His complete power, or to know Him perfectly, even as He perfectly knows Himself.

4. It may be said: The intellect and the intedligible object are of one genus, as potency and act. God, however, although not in the genus of intelligible things, as if comprehended under a genus participating in its nature, nevertheless is related to this genus as its principle. For His effects are not outside every genus of intelligible beings; wherefore even here, He can be known through His effects, and in heaven, through His essence. Moreover, a thing seems to be called “intelligible” more by negation than by, affirmation; for a thing is said to be intelligible inasmuch as it is either immune from matter or separated from it. Hence, negations may be stated in regard to divine things with truth; though affirmations are inadequate in expressing agreement, as Dionysius says (Coel. hier., chap. 2).

5. It may be answered: When a thing is known, not through its own form, but through an effect, the form of that effect takes the place of the form of the thing itself, and therefore from the effect it is possible to know whether the cause exists.

Article 3

Whether God Is the First Object Known by the Mind


1. It seems that the first object known or perceived by the mind must be God Himself. For, that in which all other things are known and through which we form judgments of what we know from all other things, is the first thing known by us, just as light is known by the eye prior to what is seen by the light; and as principles are understood before conclusions: but all things are known in the First Truth, and through that Truth we judge of all things, as Augustine says in De Trinitate and in De vera religione; therefore the First Truth is first known by us.

2. When there are many ordered causes, the influx of the first cause into the thing caused is prior to that of the second cause, and it is the last to leave the effect, as is said in Liber de causis: but since human knowledge is caused by things, the knowable or the intelligible is the cause of the mind’s intellection; therefore the first intelligible is the first to influence it: but the influence of the intelligible on the mind, as such ‘ is that it be understood; therefore God is the first object known by our intellect, since He is the first intelligible.

3. In all cognition, in which those things that are prior and simpler are first known, what is first and simplest is known first: but in human cognition. those things that are first experienced are things prior to others and simpler, as is evident, since being is that of which first the human mind forms a concept, as Avicenna says; being, moreover, is first among created things; therefore also, God first comes to the knowledge of the human mind, since He is absolutely first and most simple being.

4. That end which is the last in attainment is the first in intention: but God is the last end of the human will, to whom all other ends are ordained; and He is, therefore, the first in intention. But this could not be unless He were known; therefore God must be the first object of kliowledge.

5. That which requires no preliminary preparation in order to be fitted to the need of the workman is the first chosen for his task, rather than that which needs some labor in order to be made ready, just as one making a bench selects wood already cut rather than uncut wood: but sensible things need to be abstracted from matter by the active intellect befctre they can be understood by the possible intellect. God, on the other hand, is by His very nature altogether separate from matter: therefore He is understood by the possible intellect prior to sensible things.

6. Those things that are naturally known, and that cannot be thought of as non-existing, are what first occur to our cognition: but an idea of the existence of God is naturally implanted in all minds, as Damascene says. Neither is it possible to think of God as non-existent, as Anselm states; therefore God is the first being known by us.

Sed contra

On the contrary, according to the Philosopher, everything known by us takes its origin from sense knowledge: but God is absolutely remote from sense experience; therefore He is not first known by us, but is known last.

Again, according to the Philosopher, those things that are posterior, according to nature, are first known as far as we are concerned; and those things which are less knowable in themselves are better known as far as we are concerned. But created things are posterior and less knowable by nature than is God Himself; therefore, by us, He is known after creatures.

Again, what is promised as an ultimate reward does not come first, preceding everything done to deserve it: but knowledge of God is promised to us as the ultimate reward of all cognition and action; therefore God is not the first object known by us.

Response. I answer that it must be said: There are those who declare that the first object known by the human mind even in this life is God Himself, who is first truth and the one through whom all other things are known. But this is evidently false, since to know God through His essence constitutes the beatitude of man; wherefore it would follow that every man would be blessed.

Moreover, since in the divine essence all things said of it are one, no one would err in regard to anything he said concerning God—a thing which from experience is evidently false; furthermore, since things first in the comprehension of the intellect ought to be most certainly known, the intellect would be certain that it knew them; but it is clear that this is not the case in the proposition (as to knowing God).

This position is also repugnant to the authority of Scripture (Exod. 33:20): “Man shall not see Me and live.”

Hence there are others who say that the divine essence is not the first thing known by us in this life, but the influx of its light is, and in this way God is the first object known by us.

But this claim cannot be held; for the first influx of divine light in the mind is the natural light by which the power of intellectual life is constituted. This light, however, is not at first known by the mind; neither by cognition by which is known what this light is, since much investigation is required to know the essence of the intellect; nor by cognition by which is known whether such a light exists; for we do not perceive that we possess intellect, except inasmuch as we perceive that we understand, as is clear from the Philosopher’s words in IX Ethic. For no one knows that he understands anything, save inasmuch as he understands something intelligible. From this it is evident that cognition of an intelligible object-precedes cognition by which one knows that he himself understands, and consequently precedes the cognition by which he knows that he possesses an intellect; and so the influx of the natural light of intelligence cannot be the first thing known by us; and much less can any other kind of influx of light be the first thing known. Therefore it must be said that “the first thing known to man” is a phrase which can be understood in two ways: either according to the order of diverse potencies, or according to the order of objects in some one potency.

According to the first way, since all the knowledge of our intellect is derived from sense experience, what is made known to us by our senses is known prior to what is known by the intellect; and this is the singular, or the sensibleintelligible.

According to the other meaning, that is, according to the order of objects in any one potency, the proper object of each potency is what is first knowable by it. Since, however, in the human intellect there is an active potency and a passive one, the object of the passive potency, namely, the possible intellect, will be that which is in act through the active potency, that is, through the active intellect, since to the passive potency there must correspond that which activates it.

The active intellect, however, does not render intelligible separate forms, which are of themselves intelligible, but those forms which it abstracts from phantasms; and hence forms of this I er kind are those which our intellect knows. And amongese forms, the ones that first come to be abstracted by the intellect hold the place of priority. These, furthermore, are the forms that comprehend more notes—either after the manner of a total universal or after the manner of an integral whole—therefore the more universal things are first known to the intellect; a composite is known before its component parts, and a definition before the parts of the definition.

In this respect there is a certain imitation of the intellect found in the sense powers, which also receive as their objects things which in a certain way are abstracted from matter. For even in the case of the senses, singular things of a more general nature are the first known, as “this body” is known sooner than “this animal.”

Thus it is evident that God and other separate substances cannot in any way be the first objects of our intellection, but are understood from other things, as is said in Rom. 1:20: “For the invisible things of Him, from the creation of the world, are clearly seen, being understood by the things that are made.”

Answers to objections

1. It may be said: From the words of Augustine and from other similar sayings, it is not to be understood thai the uncreated truth itself is the proximate principle by which we know and judge of things, but that through the light conferred upon us, which is a similitude of that truth, we have cognition and judgment. Nor would this light have any efficacy except from the First Light: just as in methods of demonstration second principles would have no certitude unless founded upon the truth of first principles. Nevertheless it should not be thought that even this (natural) light is the first thing known by us. For we do not know other things by means of it, as if it were a medium for cognition of the knowable, but because (as agent) it makes other things knowable. Wherefore it could not itself be known unless it were contained among knowable things; even as light could not be seen by the eye unless manifested in color itself.

2. It may be answered: In the case of a plurality of ordered causes, the influx into the ultimate effect is not always of the same nature. Therefore it need not be that the first intelligible so influence our intellect as to be Himself an object of our knowledge; but it is only necessary that as cause He bestow the power of intellection. Or it may be said that although in the order of intelligible things God is first absolutely, yet He is not first in the order of things that are intelligible to us.

3. It may be said: Although those things which are first in the genus of things abstracted by the intellect from phantasms are first known by us, as ens and unum, nevertheless it does not follow that those which are first absolutely (simpliciter), which are not contained in the genus of any proper object, should be classed with the former [i.e., things abstracted from phantasms].

4. Answer is made: Although God is the last end in attainment and first in the intention of the natural appetancy, it is not necessary that He be first in the cognition of the human mind, which is ordained to its end, but first in the mind of the One ordaining it, as is the case in other things which by natural appetancy tend toward their own end. Nevertheless, the end is known from the beginning and intended in a certain general way, inasmuch as the mind desires its own well-being and welfare, which is possible to it only on condition that it (ultimately) possess God.

5. It may be answered: Although a process of abstraction is not required for the understanding of separate substances, they are not intelligible through the light of the active intellect; wherefore they are not the first objects of knowledge as far as our intellect is concerned.

6. It may be said: The existence of God, considered in itself, is a thing knowable in itself, since His essence is His existence; and in this way Anselm stated the matter.

Nevertheless, to us, who do not behold His essence, it is not self-evident that He exists; though cognition of it may be said to be innate inasmuch as it is through principles which are innate in us that we are easily able to perceive that God exists.

Article 4

Whether the Human Mind Is Capable of Arriving at a Knowledge of the Divine Trinity Through Natural Reason


1. It appears that the human mind is sufficiently capable of attaining to a knowledge of the divine Trinity through natural reason. Whatever belongs to being inasmuch as it is being ought especially to be found in first being: but a trinity does belong to being inasmuch as it is being, since such is found in everything, in this way: that all things have species, mode, and order, as Augustine says; therefore it is possible to know by natural reason that in God there is a Trinity.

2. No perfection can be wanting in God: but three is the number of every perfect thing, as is said in I De coelo et mundo: therefore Trinity must be attributed to God, and thus the conclusion is like that of the previous argument.

3. All inequality is reducible to prior equality, as multitude is reducible to unity: but between God and first created being there is inequality; there must, therefore, be some preceding equality, but this could be no other than that of a plurality; therefore there must be some plurality in the Divine Being.

4. Anything that is equivocal is reducible to what is univocal: but the issuing forth of creatures from God isequivocal; it is needful, therefore, to presume as prior to it a univocal procession, by which God proceeds from God, by reason of which a Trinity of persons ensues.

5. Without companionship, there can be no joy in the possession of any good: but in God there is from all eternity a most joyful possession of good; therefore, He possesses eternal companionship; but this could be no other than the companionship of divine persons, since no creature is eternal. Therefore, it is necessary to suppose a plurality of persons in the Deity.

6. It is possible to know from natural reason that God is intelligent; but from the fact that He is intelligent it follows that He conceives the Word, since this is common to every intelligence; therefore by natural reason it is possible to know of the generation of the Son and, in the same way, of the procession of love (between Father and Son: the Holy Spirit).

7. Richard of St. Victor in his De Trinitate says: “I believe without any doubt that in the case of whatever things are necessary there cannot be wanting reasons to explain them, not only probable arguments, but necessary ones”; but that God is three and one is a necessary truth, since He is eternal; therefore in proof of this there are necessary arguments of reason, and so the conclusion is as the previous one.

8. The Platonists had no knowledge of God except through reason: but they held that there were at least two persons: namely, the Father and the Mind generated by the Father, and this Mind contained the ideas of all things—a truth which we claim in regard to the Son; therefore by natural reason a plurality of persons can be known.

9. The Philosopher at the beginning of De coelo et mundo says: “Through this same number (three) we ourselves are accustomed to call upon God the Creator”; and so the conclusion is the same.

10. In this life we can in no way know what God is but only that He is: but there is a way in which we know that God is three and one, since we know it by faith; therefore this truth does not pertain to a quidditative knowledge of God, but only to an entitative knowledge. But by natural reason we can know God entitatively; therefore it is possible by natural reason to know that God is three and one.

Sed contra

Faith is of things that are not apparent to reason, as is clear from Heb. 11:1; but that God is three and one is an article of faith; therefore reason does not suffice for knowing this.

Again, natural reason has its efficacy from first principles of natural cognition: but that God is three and one cannot be deduced from principles naturally known, for these are derived from sense experience, and in sensible things there is found nothing like to three supposita of one essence; therefore God cannot be known as three and one from reason.

Moreover, according to the words of Ambrose: “It is impossible for anyone to know the secret of generation; the mind fails; the voice is silent; not only mine, but even that of the angels”; therefore natural reason does not suffice for knowledge of divine generation, and consequently for knowledge of the Trinity of persons.

Response. I answer that the truth that God is three and one is altogether a matter of faith; and in no way can it be demonstratively proved. For, although certain reasons can be found (by way of demonstration ad hoc), they are not necessary, or even very probable except to one who believes it. This is evident from the fact that in this life we know God only from His effects, as previous statements have proved. Hence, according to natural cognition, we can know nothing of God except what we can derive concerning Him from viewing the relationship of effects to Him. Thus there are things that designate His causality and His eminence over creatures and that deny in Him any of the imperfections found in effects. The existence of a Trinity of persons, however, cannot be perceived from a consideration of divine causality, since causality is common to the whole Trinity. Nor can it be known from His lacking any imperfection. Therefore in no way can it be demonstratively proved that God is three and one.

Answers to objections

1. It may be said: Those things which are many among created beings are in fact one in God: and therefore, although in every creature there is found a certain kind of trinity, it cannot be necessarily concluded from this that there is such a trinity in God, except logically, and this kind of plurality is not sufficient to prove a distinction of persons.

2. It may be answered: The perfection of the number three is found in God according even to the unity of His essence, not because His essence is subject to numeration, but because in it there is contained virtually the perfection of every number, as is said in the Arithmetica of Boethius.

3. It may be said: Apart from any distinction of persons, there is equality in the Divinity, inasmuch as Its wisdom is equal to Its power. Or it can be said that in regard to equality there are two points of consideration, namely, plurality of supposita, among whom equality exists, and unity of quantity, which is the cause of equality. The reduction of inequality to equality, therefore, does not occur by reason of the plurality of supposita, but by reason of the cause; for just as unity is the cause of equality, so inequality is the cause of plurality. Hence it must be that the cause of equality precedes the cause of inequality, but not that any kind of inequality is preceded by some kind of equality: otherwise it would be necessary in an order of numbers that there should be something before unity and duality, which are unequals; or that in unity itself there should be found plurality.

4. It must be said: Although anything equivocal is reducible to what is univocal, it is not necessary that equivocal generation should be reduced to univocal generation, but that it should be reduced to a generator which is univocal in itself. Now, in natural things we see that equivocal generations are prior to univocal because equivocal causes have an influx extending to the total species, whereas univocal causes have not, their influence extending only to one individual; and thus they are quasi-instruments of equivocal causes, just as inferior bodies are of superior.

5. It is answered: It is not possible for man to have a joyous life without companionship because he has not within himself that which makes him all-sufficient; whereas, for the same reason, animals that are self-sufficient require no association with others for preservation of life, but are solitaries. God, however, is supremely self-sufficient; wherefore, even though there were no distinction of persons, infinite joy would still be His.

6. It may be said: In God, intellect and object of intellect are the same; and therefore, from the fact that He is intelligent, it need not be supposed that in Him there is any concept really distinct from Himself, as is the case with us: Trinity of persons, however, requires real distinction.

7. It may be answered: Understanding of this passage is clarified by that which follows: “Although they (these truths) are of such kind as to escape all our endeavors.” All things that are necessary in themselves, therefore, are either known in themselves or are knowable through other things: yet not in such a way that they are necessarily apparent to us. Therefore we cannot, even as a result of all our industry, discover necessary arguments of reason sufficient to prove all necessary truths.

8. It may be said: The position of the Platonists affords no argument as regards the truth of this matter, even though it appears to do so according to words. For they did not hold that this Mind was of the same essence with God the Father, but that it was another substance proceeding from the first, and separate; and they also supposed that there was a third substance, the Soul-of-the-World, as is evidenced by Macrobius. And because all these separate substances they called “gods,” it came about that they called upon or spoke of three gods, as Augustine says in De civitate Dei (chap. 10); because they did not hold that there was anything like to the Holy Ghost, as there was to the Father and the Son. For the Soulof-the-World is not the nexus of the other two, according to their doctrine, as is the Holy Spirit between the Father and the Son; therefore they are said to have lacked the third sign, that is, knowledge of the Third Person. Or it may be said, as the more common explanation has it, that they knew two persons according to the things appropriated to power and wisdom, but not according to the things proper to them. But goodness, which is appropriated to the Holy Spirit especially, has as its effects things which they did not know.

9. It may be said: Aristotle did not have any intention of saying that God should be worshiped as three in one, but that He was honored by the ancients by the number three in their sacrifices and prayers because of the perfection of three as a number.

10. It may be answered: All things in God are of one, simple essence; but those things that in Him are one, are many in our intellem, and on this account our intellect can apprehend one of these things without the other. Therefore in this life we are able to understand the quiddity of none of these things, but only their existence; and thus it happens that one of them may be known to exist and not another: just as one might know that there is ‘ wisdom in God, but not know that there is also omnipotence; and likewise it is possible, by natural reason to know that God exists, but not that He is a Trinity, and one God.


Concerning the Manifestation of Knowledge of Divine Truth

Here four questions are proposed:

1. Whether divine truths ought to be treated of by the method of inquiry.

2. Whether there can be any science of divine truths which are founded upon faith.

3. Whether in the science of faith, which is concerning God, it is permissible to employ arguments of the natural philosophers.

4. Whether divine truths ought to be veiled by new and obscure words.

Article 1

Whether Divine Truths Ought to Be Treated of by the Method of Inquiry


1. It seems that it is not permissible to investigate divine things by the arguments of reason. In Sirach 3:22, it is said: “Seek not the things that are too high for thee”; but divine truths are, in a special way, too high for man, and particularly those truths which are of faith; therefore it is not permissible to inquire into them.

2. Punishment is not inflicted except for some fault; but, as it is said in Prov. 25:27, “He that is a searcher of majesty shall be overwhelmed by glory”; therefore, it is not right to search out those things which pertain to divine majesty.

3. Ambrose says: “Abandon arguments where faith is sought.” But in regard to divine truths, especially those concerned with the Trinity, faith is required; therefore in this matter it is not permissible to inquire into truth by arguments of reason.

4. Ambrose, in speaking of divine generation, says: “Supernal mysteries are not to be scrutinized: one may know that the Son was begotten; but how He was begotten should not be analyzed.” Accordingly, for the same reason it is not permissible to make rational investigation of those truths which pertain to the Trinity.

5. Gregory in his Homily for Easter (chap. 8) says: “Faith has no merit where human reason affords proof”; but it is wrong to lose the merit of faith; therefore it is not right to investigate matters of faith according to methods of reason.

6. All honor ought to be given to God: but divine mysteries are honored by silence; wherefore Dionysius says at the close of Coel. hier.: “Honoring by silence the hidden truth which is above us”; and with this there agrees what is said in Psalm 64, according to the text of Jerome: “Praise grows silent before You, O God,” that is, silence itself is Your praise, O God; therefore we ought to refrain ourselves in silence from searching into divine truths.

7. No one is moved to infinity, as the Philosopher says in I De Coelo et mundo, because all motion is on account of the attaining of an end [terminus], which is not to be found in infinity; but God is infinitely distant from us. Since, therefore, investigation is a kind of motion of reason toward that which is being searched out, it appears that divine truths ought not to be investigated.

Sed contra

On the other hand, it is said (1 Pet. 3:15): “Being ready always to satisfy everyone that asketh you a reason of that (faith and) hope which is in you”; but this could not be done unless we inquired reasonably into those things which are matters of faith; therefore investigation according to methods of reason into the truths of faith is necessary.

Again as is said in Titus 1:9, it pertains to a bishop that he be capable of exhorting in sound doctrine and of overcoming those contradicting it: but he cannot do this without use of argumentation; therefore one ought to employ the arguments of reason in matters of faith.

Again Augustine says in I De Trinitate: “With the help of God our Lord, we shall begin to discuss according to reason that for which they [our adversaries] seek explanation: that the Trinity is one God.” Therefore man can inquire about the Trinity according to methods of reason.

Also Augustine says in his argument against Felician: “Since without too much disagreement you recognize these two things—since you do not disregard the foregoing argument and the word of authority—I present the matter to follow in spch a way that you yourself may accept it as proof”; that is, I shall make use of arguments from reason and authority; and thus the conclusion is like the previous one.

Response. I answer that it must be said that, since the perfection of man consists in his union with God, it is right that man, by all the means which are in his power and in so far as he is able, mount up to and strive to attain to divine truths, so that his intellect may take delight in contemplation and his reason in the investigation of things of God, according to the saying of Ps. 72:28, “It is good for me to adhere to my God.” Hence also the Philosopher in X Ethic. opposes the saying of those who maintained that man ought not concern himself about divine things, but only about such as are human, saying: “One ought to be wise in regard to man, however, not according to those treating of human affairs alone, as a mortal knowing only mortal things; but, inasmuch as it is fitting for a mortal man to do so, he ought to do all things according to the best of those powers that are in him.”

In a threefold manner, however, it is possible for man to err on this point:

First, by presumption, since one might enter upon such investigation as if he could attain a perfect comprehension, and it is this kind of presumption that is denounced in Job 11:7: “Do you think you can comprehend the steps of God, and find out the Almighty perfectly?” And Hilary says: “Do not involve yourself in the hiddenness and mystery of this inconceivable nativity; do not overwhelm yourself, presuming to comprehend the loftiest of intelligible things, but understand that it is incomprehensible.”

In the second place, error arises if, in matters of faith, reason has precedence of faith and not faith of reason, to the point that one would be willing to believe only what he could know by reason, when the converse ought to be the case: wherefore Hilary says: “While believing [in a spirit of faith], inquire, discuss, carry through your speculation.”

In a third way error results from undertaking an inquiry into divine things which are beyond one’s capacity. Wherefore it is said in Rom. 12:3, “Not to be more wise than it behoveth to be wise, but to be wise unto sobriety and according as God hath divided to every one the measure of faith.” All men, indeed, have not been accorded the same measure; wherefore a thing is beyond the capacity of one which is not beyond that of another.

Answers to objections

1. It may be said: Those things are said to be too high for man which exceed his capacity, no those things which are of greater dignity according to nature: for the more man fixes his gaze upon things loftier by na ture, in accordance with his capacity, the more it is to his advantage; but in the consideration of things which in the least exceed his capacity, he easily falls into error. Therefore the gloss on this same passage says: “Heretics are produced in two ways: namely, when men, beyond their proper capacity entering upon inquiry concerning the Creator or creatures fall into errors and depart from the truth.”

2. Answer may be made: To search out is, as it were, to press one’s investigation to the very end; but this would be unlawful and presumptuous if one should so investigate divine truths as though he could attain to complete comprehension as his goal.

3. It is answered: Where faith is sought for, those arguments which are in opposition to faith and those which seek to have precedence over it are cast aside, but not those which in due manner follow it.

4. It may be said: It is not lawful in this world to inquire into divine mysteries in such a way that one would have the intention of comprehending them, as is evident from the words that follow: “It is lawful to know that He was begotten,” etc. For he undertakes an unlawful mode of inquiry who seeks to know what the nature of this nativity is, since in regard to divine things we are able to know what they are not, but not what they are.

5. It may be answered: Human reasoning may be spoken of in two ways: in one way, it may be regarded as demonstrative, forcing the intellect to believe; and this kind of reasoning cannot be possessed in regard to those truths which are of faith; but it is possible to possess this kind of reasoning in refuting those arguments which would destroy faith or assert the impossible. For, although reason cannot demonstrate those things which are of faith, neither can these same truths be demonstratively disproved. Moreover, if this kind of reason could lead ta a proving of those things which are of faith, it would deprive man of the merit of faith, because then assent would not be voluntary, but necessary.

Persuasive reasoning, however, derived from certain likenesses to those things which are set forth by faith does not void the meaning of faith, since it does not make these truths to be apparent, for there can be no resolution of them to those first principles discernable by the intellect. Nor does it take away the merit of faith, because it does not force the intellect to comprehend truth, but assent remains voluntary.

6. It may be said: God is honored by silence, but not in such a way that we may say nothing of Him or make no inquiries about Him, but, inasmuch as we understand that we lack ability to comprehend Him. Wherefore in Sirach 43: 32-34, “Glorify the Lord as much as ever you can, for He will yet far exceed, and His magnificence is wonderful. Blessing the Lord, exalt Him as much as you can: for He is above all praise. When you exalt Him put forth all your strength, and be not weary: for you can never go far enough.”

7. Answer may be made: Since God is infinitely distant from creatures, no creature is so moved unto God as to be made His equal, either in receiving from Him or in knowing Him. Therefore, by reason of the fact that God is infinitely distant from creatures, there is no terminus to the motion of creatures; but every creature is moved to this: that he may be more and more like to God, so far as this is possible, and so also the human mind ought always be moved more and more to a knowledge of God, according to the measure that is proper to it. Therefore Hilary says: “He who in pious spirit undertakes the infinite, even though he can in no wise attain it, nevertheless profits by advancing.”

Article 2

Whether There Can Be Any Science of Divine Truths Which Are Matters of Faith


1. it appears that there can be no science of those divine truths which are matters of faith. For wisdom is distinguished from science; but wisdom treats of divine truths; therefore science cannot do so.

2. As is said in I Poster., in every science one must suppose a quidditative knowledge of the subject; but in regard to God, it is impossible for us to know in any way what He is, as Damascene says; therefore it is not possible to possess any science of God.

3. It pertains to every science to consider the parts and passive potencies of its subject; but, since God is simple form [absolute act], He has not any parts that can be distinguished, nor in Him can there be any passive potencies; therefore there can be no science about God.

4. In any science, reason precedes assent, for it is demonstration which in the sciences makes one assent to what is knowable; but in regard to those truths which are of faith, the converse ought to prevail, namely, assent on account of faith ought to precede reason, as has been said; therefore, of divine truths, especially of those which are known by faith, there can be no science.

5. Every science proceeds from self-evident principles which every man accepts upon first hearing, or from principles in which he has faith because of those first principles; but the articles of faith which are first principles in matters of faith, are not principles of this same kind, since they are not per se nota nor can they be resolved by demonstration to those that are, as has been said; therefore, there can be no science of divine truths held by faith.

6. Faith is not of those things that are apparent: but science is of things that are apparent, because through science those things that are treated of come to be clearly seen; therefore, concerning divine truths that are held by faith there can be no science.

7. Understanding is the principle of every science, because from the intellection of principles one comes to scientific knowledge of conclusions: but in those things that are of faith, intellection is not the beginning, but the end, for, as is said in Is. 7:9, “If you will not believe, you shall not understand”; therefore there can be no science of divine truths held by faith.

Sed contra

But on the contrary is what Augustine says in XII De Trinitate: “To that science only do I attribute any value by which faith is well served, which leads to, produces, defends, and strengthens happiness”; therefore there is a science of the truths of faith.

Also, Wis. 10:10: “She gave him the science of the saints”, that is, of the truths of faith, because no other science can be here meant except that by which saints are distinguished from sinners, which is the science of faith.

Also the Apostle in speaking of the knowledge of the faithfu says in 1 Cor. 8:7: “But there is not knowledge in everyone,” and thus we come to the same conclusion as before.

Response. I answer that, since the essence of science consists in this, that from things known a knowledge of things previously unknown is derived, and this may occur in relation to divine truths, evidently there can be a science of divine things.

But knowledge of divine truths can be thought of in two ways. In one way, as on our part, such truths are not knowable except from created things, of which we have a knowledge derived from sense experience. In another way, on the part of the nature of these things themselves, they are, in themselves, most knowable; and although they are not known by us according to their essences, they are known by God and by the blessed according to their proper mode; and so science of divine things must be considered in a twofold manner. One is according to our mode of knowledge, in which knowledge of sensible things serves as the principle for coming to a knowledge of divine; and it was in this way that the philosophers handed down a traditional science of divine things, calling first philosophy a divine science. The other mode is according to that of divine things themselves as they are understood in themselves. This is, indeed, a mode of knowledge which we cannot possess perfectly in this life; but there is for us, even in this life, a certain participation and assimilation to such a cognition of divine truth, inasmuch as through the faith which is infused into our souls we adhere to the very First Truth on account of Itself. And as God, since He knows Himself, knows in a way that is His own, that is, by simple intuition, not by discursive thought, so we, from those truths that we possess in adhering to First Truth, come to a knowledge of other truths, according to our own mode of cognition, namely, by proceeding from principles to conclusions. Wherefore, those truths that we hold in the first place by faith are for us, as it were, first principles in this science, and the other truths to which we attain are quasi-conclusions. From this it is evident that this science is of a higher order than that which the philosophers traditionally termed divine, since it proceeds from higher principles.

Answers to objections

1. It may be said: Wisdom is not distinguished from science as opposed to it, but as related to science by adding to it. For wisdom is, indeed, as the Philosopher says in VI Ethic., the head of all the sciences, regulating all others inasmuch as it treats of highest principles: on this account it is also called “the goddess of sciences” in I Metaph.; and much more is this true of that wisdom which is not only about highest principles, but from highest principles. Moreover, the function of wisdom is to order, and therefore this highest science, which orders and rules all others, is called wisdom; just as in mechanical arts we call those men wise who direct others, as the architects: but the name of “science” is also left to others that are inferior, and accordingly science is distinguished from wisdom as a property from a definition (i.e., as properties flow necessarily from an essence, so do the other sciences from wisdom).

2. It may be said: As has been previously declared, since causes are known through their effects, the knowledge of an effect substitutes for the quidditative knowledge of the cause; this is necessarily required in those sciences treating of things that cannot be known through themselves: thus, for us to have a science of divine things, it is not necessary that we first have a quidditative knowledge of God. Or, again, it can be said that what we know God is not, takes the place, in divine science, of a cognition of what He is: for as one thing is distinguished from others by what it is, so God is here known by,that which He is not.

3. It may be answered: In science the parts of a subject are not to be understood only as subjective or integral parts; but the parts of a subject are all those things of which knowledge is required in order to have cognition of the subject, since all things of this sort are not dealt with in a co-science except inasmuch as they are related to the subject. Those also are called passive potencies which can be proved in regard to anything, whether they are negations or relations to other things. And many such things can be proved in regard to God, both from naturally known principles and from principles of faith.

4. It may be answered: In any science whatever there are certain things that serve as principles, and others as conclusions. Hence the reasoning process set forth in the sciences precedes the assent given to a conclusion, but follows upon assent to principles, since it proceeds from them. Now, it is true that the articles of faith are in this science rather principles aian conclusions, but they must be defended against those opposing them, as the Philosopher (IV Metaph.) proves against those denying first principles: for they may be made clearer of understanding by certain similitudes, by inducing results of opposing naturally known principles, but they cannot be proved by demonstrative reasoning.

5. It must be said: Even in those sciences handed down to us by human tradition, there are certain principles in some of them which are not universally known, but which presuppose truths derived from a higher science, just as in subordinate sciences certain things taken from superior sciences are assumed and believed to be true; and truths of this kind are not per se nota except in the higher sciences. This is the case with the articles of faith; for they are principles of that science leading to knowledge of divine things, since those truths which are per se nota in the knowledge which God has of Himself, are presupposed in our science; and He is believed as the one manifesting these truths to us through His messengers, even as the doctor believes from the word of the physicist that there are four elements.

6. Answer is made: The evident truths of a science proceed from the evident truth of principles. Wherefore a science does not make clear the truth of its principles, but makes clear that of its conclusions: and in this same way the science of which we now speak does not make evident the things of which we have faith, but on the basis of them, it makes other things evident with the same certitude as that belonging to their first principles.

7. It may be said: Understanding is always the first principle of any science, but not always the proximate principle; rather, it is often faith which is the proximate principle of a science, as is evident in the case of the subordinate sciences; since their conclusions proceed from faith in truths accepted on the authority of a superior science as from a proximate principle, but from the understanding of scientists in the superior field who have intellectual certitude of these created truths as from their ultimate principle. So likewise the proximate principle of this divine science is faith, but the first principle is the divine intellect to the revelation of which we give the assent of faith; but faith is in us that we may attain to an understanding of those things we believe; in the same way that a scientist in an inferior field, if he should gain knowledge of a higher, would then possess understanding and science of truths which previously were accepted only on faith.

Article 3

Whether in the Science of Faith, Which Is Concerning God, it Is Permissible to Use the Rational Arguments of the Natural Philosophers


1. It seems that in regard to those truths that are of faith it is not right to employ the rational arguments of the natural philosophers, for, according to 1 Cor. 1:17, “Christ sent me not to baptize, but to preach the gospel: not kisdom of speech”; that is, “in the doctrine of the philosophers,” as the gloss says. And concerning the line (1 Cor. 1:20), “Where is the disputer of this world?” the gloss says: “The disputer is he who searches into the secrets of nature; such men God does not accept as preachers.” And on the line (1 Cor. 2:4), “And my speech and my preaching was not in the persuasive words of human wisdom,” the gloss says: “Although the words were persuasive, they were not so because of human wisdom, as is the word of pseudo-apostles.”

From all these lines it is evident that in matters of faith it is not lawful to employ philosophical reasoning.

2. On that line (Is. 15:1), “Because in the night Ar of Moab is laid waste,” the gloss says: “Ar, that is, the adversary, namely, secular science, which is the adversary of God”; therefore, etc.

3. Ambrose says: “The deepest mysteries of faith are free from the reasonings of the philosophers”; therefore, when a matter of faith is dealt with, the reasonings and words of the philosophers ought not to be used.

4. Jerome relates in a letter to Eustochium that in vision he was beaten, according to divine justice, because he had read the books of Cicero, and that those standing by besought that leniency might be granted on account of his youth, and that afterward the extreme penalty should be exacted if he read again the books of the Gentiles; wherefore, calling upon the name of God, he exclaimed: “If ever I shall possess secular books, if ever I read them, I shall have denied You”; therefore it is not lawful to use them in treating of divine things.

5. In Scripture, secular wisdom is often represented by water, but divine wisdom by wine. Now, according to Is., chap. 1, the innkeepers are upbraided for mixing water with wine; therefore the doctors are blameworthy for their mingling of philosophical doctrine with sacred Scripture.

6. Jerome says, in his gloss on Hosea, chap. 2, “With heretics we ought not to have even names in common.” But heretics use the arguments of philosophers to destroy faith, as is maintained in the gloss on Prov., chap, 7 and Is., chap. 15; therefore Catholics ought not to use such in their discussions.

7. Every science has its proper principles, and thus also sacred doctrine has those that belong to it, namely, the articles of faith; but in other sciences the process is not valid if principles are saken from a different science, but each ought to proceed from its own principles, according to the teaching of the Philosopher (I Poster.); therefore the method is not permissible in sacred doctrine.

8. If the doctrine of anyone is repudiated in any respect, the authority of his teaching will not be valid in proving anything; wherefore Augustine says that, if in sacred doctrine we discover some falsity, the authority of that teaching is destroyed for confirming anything in regard to faith; but sacred doctrine repudiates the doctrine of the philosophers in many ways, because many errors are found among them; therefore their authority has no efficacy in proving anything (regarding sacred doctrine).

Sed contra

But on the contrary, the Apostle (Titus 1: 12) makes use of a verse from the poet Epimenides, saying, “The Cretans are always liars, evil beasts,” etc.; and (1 Cor. 15:33) he employs the words of Menander: “Evil communications corrupt good manners”; and in Acts 17:28 are the words of Aratus, “For we are also his (i.e., God’s) offspring.” Therefore it is licit for other doctors of divine Scripture also to make use of the arguments of the philosophers.

Again, Jerome, in a letter to Magnus, a famous orator of Rome, having enumerated many doctors of Scripture, such as Basil and Gregory, adds: “All these have so intermingled in their books the teachings and the sayings of the philosophers that one knows not which to admire first in them, their secular erudition or their knowledge of the Scriptures.” But this they would not have done had such been illicit or useless.

Also Jerome in a letter to Pammachius about the death of Paula says: you have become enamored of the captive woman, secular wisdom, and captivated by her beauty, cut her hair and her finger nails, cut away the enticement of her tresses and the adornments of her words, bathe her with prophetic niter, and, lying with her, say: ‘His left hand under my head, and his right hand shall embrace me’ (Cant. 8:3), and many children will the captive woman give to you, and from the Moabite, Israelites will be born to you.” Therefore with fruitful results some make use of secular wisdom.

Again Augustine (II De Trinitate) says: “I shall not be without zeal in seeking out knowledge of God, whether through Scripture or creatures”; but knowledge of God through creaturegis given in philosophy; therefore it is not unfitting that in sacred doctrine one should make use of philosophical reasoning.

Again Augustine (Book II, De doctrina Christiana) says: “If the philosophers have by chance uttered truths helpful to our faith, they are not only not to be feared, but rather those truths ought to be taken from them as from unjust possessors and used to our advantage.” Thus the conclusion is as before.

Also on the saying in Dan. 1:8, “But Daniel purposed in his heart,” the gloss says: “If anyone ignorant of mathematics should write in opposition to the mathematicians, or knowing nothing of philosophy should argue against the philosophers, would he not be derided?” But doctors of sacred Scripture must at times argue with philosophers; therefore it is needful that they make use of philosophy.

Response. I answer that it must be said that gifts of grace are added to those of nature in such a way that they do not destroy the latter, but rather perfect them; wherefore also the light of faith, which is gratuitously infused into our minds, does not destroy the natural light of cognition, which is in us by natuise. For although the natural light of the human mind is insufficient to reveal those truths revealed by faith, yet it is impossible that those things which God has manifested to us by faith should be contrary to those which are evident to us by natural knowledge. In this case one would necessarily be false: and since both kinds of truth are from God, God would be the author of error, a thing which is impossible. Rather, since in imperfect things there is found some imitation of the perfect, though the image is deficient, in those things known by natural reason there are certain similitudes of the truths revealed by faith. Now, as sacred doctrine is founded upon the light of faith, so philosophy depends upon the light of natural reason; wherefore it is impossible that philosophical truths are contrary to those that are of faith; but they are deficient as compared to them. Nevertheless they incorporate some similitudes of those higher truths, and some things that are preparatory for them, just as nature is the preamble to grace.

If, however, anything is found in the teachings of the philosophers contrary to faith, this error does not properly belong to philosophy, but is due to an abuse of philosophy owing to the insufficiency of reason. Therefore also it is possible from the principles of philosophy to refute an error of this kind, either by showing it to be altogether impossible, or not to be necessary. For just as those things which are of faith cannot be demonstratively proved, so certain things contrary to them cannot be demonstratively shown to be false, but they can be shown not to be necessary.

Thus, in sacred doctrine we are able to make a threefold use of philosophy:

1. First, to demonstrate those truths that are preambles of faith and that have a necessary place in the science of faith. Such are the truths about God that can be proved by natural reason—that God exists, that God is one; such truths about God or about His creatures, subject to philosophical proof, faith presupposes.

2. Secondly, to give a clearer notion, by certain similitudes, of the truths of faith, as Augustine in his book, De Trinitate, employed any comparisons taken from the teachings of the philosophers to aid understanding of the Trinity.

3. In the third place, to resist those who speak against the faith, either by showing that their statements are false, or by showing that they are not necessarily true.

Nevertheless, in the use of philosophy in sacred Scripture, there can be a twofold error:

In one way, by using doctrines contrary to faith, which are not truths of philosophy, but rather error, or abuse of philosophy, as Origen did.

In another way, by using them in such manner as to include under the measure of philosophy truths of faith, as if one should be willing to believe nothing except what could be held by philosophic reasoning; when, on the contrary, philosophy should be subject to the measure of faith, according to the saying of the Apostle (2 Cor. 10:5), “Bringing into captivity every understanding unto the obedience of Christ.”

Answers to objections

1. It may be said: From all these words it is shown that philosophical doctrine ought not to be used as if it had first place, as if on account of it one believed by faith; nevertheless the fact is not disproved that doctors of sacred learning may employ philosophy, as it were, secondarily. Wherefore, on the saying (1 Cor. 1:19), “I will destroy the wisdom of the wise,” the gloss adds: “This he does not say because the understanding of truth can be worthy of God’s anger, but because the false prudence of those who trusted in their erudition is worthy of reproof.”

Nevertheless, in order that all that is of faith might be attributed not to human power or wisdom but to God, God willed that the primitive preaching of the apostles should be in infirmity and simplicity; though, on the other hand, with the later advent of power and secular wisdom, He manifested by the victory of the faith that the world is subject to God as much by wisdom as by power.

2. It may be said: Secular wisdom is said to be contrary to God in so far as it is an abuse of wisdom (i.e., erroneous) as when heretics abuse it, but not in so far as it is true.

3. It may be answered: The sacred deposit of the truth of faith is said to be free from philosophical doctrine inasmuch as it is not confined by the limits of philosophy.

4. It may be said: Jerome was so influenced by certain books of the Gentiles that he contemned, in a way, sacred Scripture: wherefore he himself says: “If I began to read it while turning over the words of the Prophets in my own mind, their crude expression filled me with distaste.” And no one will deny that such was reprehensible.

5. It may be said: No conclusive argument can be drawn from figurative speech, as the Master (Peter Lombard) says. Dionysius also says in his letter to Titus that symbolic theology has no weight of proof, especially when such interprets no authority. Nevertheless it can be said that When one of two things passes into the nature of another, the product is not considered a mixture except when the nature of both is altered. Wherefore those who use philosophical doctrines in sacred Scripture in such a way as to subject them to the service of faith, do not mix water with wine, but change water into wine.

6. It may be said: Jerome is speaking of those arguments that were invented by heretics to give support to their errors; but such doctrines do not belong to philosophy; rather they lead only to error; and consequently on their account che truths of philosophy ought not be shunned.

7. Answer may be made: Sciences which are ordered to one another are so related that one can use the principles of another, just as posterior sciences can use the principles of prior sciences, whether they are superior or inferior: wherefore metaphysics, which is superior in dignity to all, uses truths that have been proved in other sciences. And in like manner theology—although all other sciences are related to it in the order of generation, as serving it and as preambles to it—can make use of the principles of all the others, even if they are posterior to it in dignity.

8. It may be said: Inasmuch as sacred doctrine makes use of the teachings of philosophy for their own sake, it does not accept them on account of the authority of those who taught them, but on account of the reasonableness of the doctrine; wherefore it accepts truth well said and rejects other things: but when it uses these doctrines to refute certain errors, it uses them inasmuch as their authority is esteemed by those whose refutation is desired, because the testimony of an adversary has in that case greater weight.

Article 4

Whether Divine Truths Ought to Be Concealed by New and Obscure Words


1. It seems that in the science of faith divine truths ought not to be veiled over by obscurity of words, for it is said in Prov. 14:6, “The learning of the wise is easy.” Therefore these truths ought to be presented without obscurity of words.

2. According to Sirach 4:28, “Hide not thy wisdom in her beauty,” and Prov. 11:26, “He that hideth up corn (the gloss says that preaching is here meant) shall be cursed among the people.” Therefore the words of sacred doctrine ought not to be hidden.

3. The text of Matt. 10:27, “That which I tell you in the dark (gloss, in mystery) speak ye in the light (gloss, openly).” Therefore the obscure truths of faith ought to be made more manifest, rather than hidden by the difficulties of words.

4. The doctors of truths of faith are debtors to wise and unwise, as is evident from Rom. 1:14: therefore they ought so to speak that they may be understood by great and small, that is, without obscurity of words.

5. Wis. 7:13, “Which I have learned without guile, and communicate without envy”; but those who hide do not, communicate; therefore they seem guilty of envy.

6. Augustine in IV De doctrina Christiana says: “Those explaining sacred Scripture ought not to speak in such a way that they themselves need explanation as of the same authority; but in all their sermons they ought to strive primarily and especially to be understood, and to declare these truths with as much clarity as possible so that he would be very dull who would not comprehend them.”

Sed contra

But on the contrary is that which is said in Matt, 7:6, “Give not that which is holy to dogs,” on which the gloss comments: “A hidden thing is more eagerly sought for, a thing concealed appears more worthy of veneration, that which is a long time sought for is held more dear.” Since, therefore, sacred writings ought to be regarded with the greatest veneration, it seems that it is expedient they be discussed with obscurity of speech.

Again, Dionysius (I Eccles. hier.) says: “Do not reveal to another every holy thing in praise of God, except those forms of praise generally ordained; that is, those divine rites by which all the sacraments are surrounded should not be revealed except to those like yourself”; but if they were written in conspicuous words, they would be apparent to all; therefore the secrets of faith are to be concealed by obscuring words.

Also it is said in Luke 8:10, “To you it is given to know the mystery of the kingdom of God” (that is, to have understanding of the Scriptures, as is evident from the gloss); “but to the rest in parables.” Therefore one ought by obscurity in speech conceal”We sacred truths from the multitude.

Response. I answer that the words of a teacher ought to be so moderated that they result to the profit and not to the detriment of the one hearing him. Now, there are certain things which on being heard harm no one, as are the truths which all are held responsible to know: and such ought not to be hidden but openly proposed to all. But there are others which, if openly presented, cause harm in those hearing them; and this can occur for two reasons: in one way, if the secret truths of faith are revealed to infidels who oppose the faith and so come to be derided by them. On this account it is said in Matt. 7:6, “Give not that which is holy to dogs.” And Dionysius (II Coel. hierar.) says, “Listen reverently to these words, to this doctrine given for our instruction by the divinity of divinities, and hide these holy teachings in your minds, shielding them from the unclean multitude so that you may keep them as uniform as possible.”

Secondly, if any subtleties are proposed to uncultivated people, these folk may find in the imperfect comprehension of them matter for error; wherefore, in 1 Cor. 3:1 it is said: “And I, brethren, could not speak to you as unto spiritual, but as unto carnal. As unto little,ones in Christ, I gave you milk to drink, not meat.” And therefore also, on Exod. 21:33, “If a man open a pit,” the gloss of Gregory says: “He who in sacred eloquence now understands lofty things should cover over these sublime truths by silence when in the presence of those who do not comprehend them, lest through some scandal of mind he cause the loss of some little one among the faithful or of an infidel who otherwise might have come to believe. Those truths, therefore, ought to be hidden from those to whom they might do harm; but a distinction can be made as regards speaking, since these same truths may be privately revealed to the wise, though publicly silence is kept regarding them.”

Thus, Augustine (IV De doctrina Christiana) says: “Where certain truths are, by reason of their own character, not comprehensible, or scarcely so, even when explained with every effort on the part of the speaker to make them clear, these one rarely dwells upon with a general audience, or never mentions, at all: but in writing, the same distinction cannot be adhered to, because a book, once published, can fall into the hands of any one at all, and therefore some truths should be shielded by obscuring words so that they may profit those who will understand them and be hidden from the simple who will not comprehend them.”

And by this procedure no harm is done to anyone, because those who understand are held by that which they read, but those who do not understand are not compelled to continue reading. And therefore Augustine says in the same place: “In books which are, so written that they somehow keep a hold on the attention of the reader who understands them, but cause no harm to the one who does not understand them and so is unwilling to read further, there is no failure in duty on the part of the author as long as we bring these truths, even though they are so difficult of comprehension, to the understanding of some.”

Answers to objections

1. It is answered: The authority quoted is not relevant to the proposition. For it is not to be understood that the teaching of prudent men be “easy” in the active sense; that is, that they easily teach everything; but in the passive sense: that such men are easily taught, as is evident from the gloss.

2. It may be answered: These authorities speak of hiding truths which ought to be made manifest; wherefore it is previously said in Sirach 4:28, “Refrain not to speak in the time of salvation.” By this, however, there is no denial of the fact that gore are mysteries which ought to be concealed by obscuring words.

3. It may be said: The doctrine of Christ ought to be taught publicly and openly to this extent: that the truths expedie nt for each one to know be made clear. Things that are not expedient, however, need not be publicly taught.

4. It may be answered: The doctors of sacred Scripture are not debtors to the wise and to the foolish in such a way that they must propose the same truths to both, but that they propose to each what is to the advantage of each.

5. It may be said: Subtle truths are not concealed from the multitude on account of envy, but rather out of due discretion.

6. It may be answered: Augustine is here speaking of explanations made orally to the people, not of those transmitted in writing, as is evident from what follows.


Boethius’ Text There are many who claim as theirs the dignity of the Christian religion; but that form of faith has supreme authority, and has it exclusively, which, both on account of the universal character of the rules and doctrines affirming its authority, and because the worship in which they are expressed has spread throughout the world, is called catholic or universal.

1.1.2 The belief of this religion concerning the Trinity is as follows: The Father is God, the Son is God, the Holy Spirit is God.

1.2.1 Therefore, Father, Son, and Holy Spirit are one God, not three Gods. The nature of Their Unity is such that there is no difference. Difference cannot be avoided by those who add to or take from the Unity, as for instance the Arians, who by graduating the Trinity according to merit, break it up and convert it to Plurality. For the essence of plurality is otherness; apart from otherness plurality is unintelligible. In fact, the difference between things is to be found in genus or species or number.

2.1 In as many ways as things are the same, in the same number of ways they are said to be diverse.

2.2 Sameness is predicated in three ways: by genus; e.g., a man and a horse, because of their common genus, animal. By species; e.g., Cato and Cicero, because of their common species, man. By number; e.g., Tullius and Cicero, because they are numerically one. Similarly difference is expressed by genus, species, and number.

2.3 But a variety of accidents brings about numerical difference; three men differ neither by genus nor species, but by their accidents, for if we mentally remove from them all other accidents, still each one occupies a different place which cannot possibly be regarded as the same for each, since two bodies cannot occupy the same place, and place is an accident. Wherefore it is because men are plural by their accidents that they are plural in number.

St. Thomas’ Commentary

Hereupon, after the Prooemium, Boethius begins his treatise De Trinitate Personarum, et Unitate divinae essentiae: and this book is divided into two parts. First, he discusses those things which tain to the unity of the divine essence, making opposition the Arians. Secondly, he treats of those things which pertain to the Trinity of persons, in opposition to Sabellius, beginning: “In as many ways as things are the same, in the same number of ways they are said to be diverse.”

The first part is also divided into two sections. In the first, he proposes the doctrine of the Catholic faith in regard to the unity of the divine essence. Secondly, he investigates the truth of the doctrine proposed when he says: “Therefore...” In the first section he treats of two things. First, he represents the condition of that faith whose doctrine he intends to explain. Secondly, he sets forth the doctrine of the faith he has described concerning this proposition, saying: “The belief of this religion concerning the Trinity.” He describes this religion in a twofold manner, namely, by comparison with heretical cults, which it excels, and also in its own name since it is called catholic or universal. He says, therefore, that there are many, that is, many sects of diverse heresies, who make unlawful claims, since they unduly attribute to themselves the honor of the Christian religion, that is, the honor which ought to be paid to it: namely, that all others should be subject to it. 1 John 5:4: “This is the victory that overcomes the world, our faith.” Or, again, they claim the dignity which belongs to the Christian religion in that it manifests the glory of God by believing those truths which have been divinely revealed. “But that form of faith has supreme authority, and has it exclusively.” Here he adds the two things that make it distinct both according to truth and according to reputation. Now according to the truth of the matter, heretics are not Christians, since they cut themselves off from the teachings of Christ, and in this respect the Catholic faith alone is valid. But according to appearances and in the opinion of men, heretics are called Christians because they do indeed still, at least in word, confess the name of Christ; and according to this aspect, the Catholic faith is not the only one, but holds the place of greater authority.

That this religion is the more common and the more widely diffused is understood when he says, “is called catholic or universal.” Now this is the same thing; for catholic in the Greek, means the same as the Latin universal. For the use of this name, he assigns two reasons, saying: “On account of the precepts of its universal rules,” for the precepts which the Catholic religion sets forth are not to be observed by one race alone, but by all: and in this respect it differs especially from the Law of Moses which gave precepts to one people alone. Likewise even individual heresies propose rules that are accommodated to their own members only; while the Catholic faith, having the care of all, gives its precepts to all: not to the unmarried alone, as do the Manichaeans, but also to the married; not to the innocent alone, as do the Novatians, but to sinners as well, for whom that sect would make salvation impossible. Wherefore he adds: “the authority of this religion is evident because of its universal rules,” on account of which all ought to be subject to it.

Or they may be called universal rules since there is in them no falsity or any admixture of evil, neither in any essential article or accidentally. Then he adds another reason, saying: “Because the worship in which they are expressed has spread throughout the world,” a thing which is evidently in accord with that saying of Ps. 18:5: “Their sound has gone forth into all the earth: and their words unto the ends of the world.”

1.1.2 Hereupon he next sets forth the doctrine of the Catholic faith concerning the question proposed: “The belief of this religion concerning the Trinity.” Concerning this, he does three things: First, he presents the teaching of the Catholic faith on the unity of the Trinity. Secondly, the reason for this opinion: “The principle of this unity.” Thirdly, he shows the fitness of the reason, saying: “Now the essence of plurality.” Moreover, he proposes the opinion of Catholic faith in a certain argumentative form, because faith is called “the evidence of things that appear not” (Heb. 11:1). In the same argument, indeed, from the fact that divinity is attributed equally to each of the Persons, he concludes that of all three the name “God” is ‘Predicated not plurally, as taken together, but individually. Next he assigns the reason for this belief. First, he states the reason, and secondly, he explains it by its contrary where he says: “Difference cannot be avoided by those who add to or take from the Unity.” Therefore he says: “The nature of Their Unity is such that there is no difference,” namely, the Unity of Deity in the three Persons, as confessed by the Catholic faith. From this the conclusion following upon the foregoing words is that Deity without difference is attributed to each of the three Persons; ( and this reasoning he explains by its contrary saying: “Difference cannot be avoided by those who add to or take from the Unity (of the Deity)”: that is, who hold that one Person is greater or less than the others, as the Arians, who make the Father greater than the Son. Wherefore he continues: “As for instance the Arians, who by graduating the Trinity, break it up”; that is, by graduating the Trinity according to dignity, since they make the Son subject to the Father, and the Holy Spirit to both Father and Son, and so “convert it to Plurality”; that is, produce diversity by dividing the Deity among the Persons. For from division there follows plurality. Conversely, Catholics who confess an equality of the Persons, an equality without difference, make profession of consequent Unity. Next, he shows that the foregoing reasoning is valid, saying: “For the essence of plurality is otherness,” and first he points out the necessity possessed by this reasoning. Secondly, what in the demonstration itself had been supposed is made clear: “In fact, the difference between three or more things lies in genus or species or number.” Regarding the first point he does two things. First he shows that otherness is the principle of plurality, understanding by “otherness” any difference by which things can be constituted among themselves as other. And he prefers to say “otherness” rather than “separateness” because not only substantial differences constitute plurality, since they make another thing, but accidental differences also constitute plurality, since they make for otherness: they make a thing other. Now otherness follows upon separateness; but the converse is not true. And the reason for the deduction of the Arians follows from this supposition. For if otherness is the principle of plurality, and positing a cause posits its effect, then supposing in them that otherness is by augmentation and diminution, plurality of divinity would follow. Secondly, he proposes that otherness is properly the principle of plurality, because, except for it, understanding of plurality is impossible; and according to this principle is the Catholic explanation of divine unity: for if a proper cause is taken away, so also is the effect. If, therefore, in the three Persons there is no otherness of Deity, there will be no plurality, but unity. Next, he proves what was supposed, namely, that otherness is the proper principle of plurality, when he says, “In fact, the difference between three or more things.” And the reason is that in all things that differ in genus or species or number, there is some otherness or difference which is the cause of plurality or, diversity. But all plural things, whether three or more, are diverse either generically, specifically, or numerically; therefore some kind of otherness is the principle of all plurality.

2.1 In explaining this, he does three things. First, he states the minor; secondly its proof, beginning, “In as many ways as things are the same, in the same number of ways they are said to be diverse.” This is [the demonstration of] the proof: In as many ways as things are said to be the same, in the same number of ways they are said to be diverse. But things are said to be the same in three ways, namely, in genus, species, and number. Therefore things are said to be diverse in the same number of ways. The first is supposed from what is stated in I Topic., that as much is said of one of two opposites as is said of the other: and from the saying of X Metaph., that the same and different are opposites.

2.2 The second is made clear by examples and supposes what is said in I Topic.

2.3 Thirdly, he proves the major in regard to that point which might be held in doubt, saying: “But a variety of accidents brings about numerical difference.” That the diversity of those things which are diverse according to genus or species must have as principle some otherness, is evident from the name itself. For from the fact that things are of different genera it is evident that a different, or other, genus belongs to each; and if they differ in species, it is because they are contained under other species. But in the case of things which are said to be diverse numerically, it is not evident from the name itself that otherness is the principle of plurality. Furthermore, it might rather appear to be the converse according to the name and that plurality, which is designated by number, might be the principle of diversity, since things numerically different are different according to the same name employed when difference is by genus or species: Therefore, to prove the major of his syllogism, he shows that this difference by which things are said to differ numerically is produced by a certain kind of otherness or variety. He proves this by the fact that in three men who agree in genus and species, but who differ numerically, there is found accidental otherness, just as between man and ox there is specific otherness and between man and stone generic otherness. Wherefore, as man and ox differ specifically, so two men differ accidentally.

And because some one might be able to say that accidental variety is not the cause of numerical plurality since, if accidents are done away with-either removed actually, as when separable, or by the mind and in thought, as when inseparable—substance still remains, since accident is that which can be present or absent without corruption of the substance: therefore he forestalls this objection, saying that, although all accidents might indeed be separated from a substance by the mind, nevertheless the diversity of one accident could in no way, even by the mind, be separated from diverse individuals, namely, diversity of place. For two individuals cannot be in the same place either according to fact or according to any fiction of the mind, since this cannot be understood or imagined. Wherefore he concludes that from the fact that men are plural in number they are plural by reason of accidents; that is, they are for this reason diversified; and with this is terminated the teaching of this part of the treatise.


Concerning Those Things That Pertain to the Knowledge Possessed by Faith

This question is twofold. First, there is consideration of those things that pertain to the communion of faith: secondly, of those that pertain to the cause of plurality.

In regard to the first, four questions are asked:

1. Whether faith is necessary for mankind.

2. How faith is related to religion.

3. Whether the true faith is aptly called Catholic or universal.

4. Whether this is the, confession of the true faith: that Father, Son, and Holy Spirit each is God, and that the Three are one God without any difference owing to inequality.

Article 1

Whether Faith Is Necessary for Mankind


1. It seems that faith should not be considered necessary for mankind. As is said in Eccles. 7:1, “What needeth a man to seek things that are above him?” This is to say, there is no need. But those things that are believed by faith are above man, as exceeding his reason; otherwise ~his reason, which is the cause of science, would suffice. Therefore it was not necessary for man that, over and above the truths of reason, he should be taught those of faith.

2. God established human nature as something perfect when He created it. Deut. 32:4, “The works of God are perfect.” But from the ability bestowed upon the human mind according to its original condition, man cannot attain to those things which must be known by faith; otherwise he would be able to possess scientific knowledge of them, a knowledge which is caused by the fact that conclusions are resolved into naturally known principles. Since, therefore, a thing is called perfect if it lacks nothing that it ought to possess, as is said in V Metaph., it seems that man does not require faith.

3. Every wise man makes choice of the shorter way to reach a goal: but it would appear exceedingly difficult for a creature to believe truths which are above reason and, in the case of men, extremely dangerous, since many fall away from the state of salvation because they do not believe; therefore, it seems that God, who is all-wise, ought not to have established faith as the way of salvation for men.

4. Whenever there is acceptance of knowledge without judgment, the road to error is easy; but we have in ourselves no ability by which we are able to judge of the things which we accept by faith, since our natural judgment does not extend to truths of this kind, as they exceed reason; therefore evidently the road to error is an easy one for us, and so it would appear rather harmful than useful for man that he should be directed to God by the way of faith.

5. As Dionysius says, it is an evil for man to exist apart from reason; but man in adhering to faith departs from reason, and in this he is even accustomed to despise reason; therefore it seems that such a way is evil for men.

Sed contra

But on the contrary, it is said in Heb. 11:6, “Without faith it is impossible to please God”; but it is supremely necessary for man that he be pleasing to God, since otherwise he can neither do nor possess any good; therefore faith is most necessary for man.

Again, it is most necessary for man to know the truth, since beatitude is joy in knowing the truth, as Augustine says; but faith establishes believers in truth and establishes truth in them, as Dionysius says (De div. nom., chap. 7); therefore faith is most necessary for man.

Again, that without which human society cannot be conserved is especially necessary for man, since man is a political animal, as is said in VIII Ethic.; but without faith human society cannot be preserved, since it is requisite that one man believe in the promises of another and in his testimony and the like, for this is necessary if they are to live together; therefore faith is most necessary for mankind.

Response. I answer that it must be said that faith has something in common with opinion, and something in common with knowledge and understanding, by reason of which it holds a position midway between opinion and understanding or science, according to Hugh of St. Victor. In common with understanding and knowledge, it possesses certain and fixed assent; and in this it differs from opinion, which accepts one of two opposites, though with fear that the other may be true, and on account of this doubt it fluctuates between two contraries. But, in common with opinion, faith is concerned with things that are not naturally possible to our understanding, and in this respect it differs from science and intellection.

That a thing should not be apparent to human understanding can arise for two reasons, as is said in II Metaph.: namely, because of lack of knowability in things themselves, and because of lack of intellectual ability on our part.

1. It may be due to lack on the part of things, as in the case of singular and contingent things which are remote from our senses, like the deeds and words and thoughts of men; for these are of such a nature that they may be known to one man, but unknown to others. And since among men dwelling together one man should deal with another as with himself in what he is not self-sufficient, therefore it is needful that he be able to stand with as much certainty on what another knows, but of which he himself is ignorant, as upon the truths which he himself knows. Hence it is that in human society faith is necessary in order that one man give credence to the words of another, and this is the foundation of justice, as Tullius says in his book, De officiis. Hence also it is that no lie is without sin, since every lie derogates from that faith which is so necessary.

2. The truth of things may also not be evident because of defect on our part, as in the case of divine and necessary things which, according to their own nature, are most knowable. Wherefore, to understand them, we are not capable of immediate intellection, from the very beginning, since it is in accordance with our nature to attain from things less knowable and posterior in themselves, to knowledge of those that are themselves more knowable and prior. But since from none of those things that we know last do we have any knowledge of those that we know first, it is needful for us even at first to have some notion of those things that are most knowable in themselves; but this cannot be except by believing. And this is evident even in the order of the sciences; since that science which is concerned with highest causes, namely, metaphysics, comes last in human knowledge; yet in sciences that are preambles to it there must be supposed certain truths which only in it are more fully revealed; therefore every science has some suppositions that must be believed in order to cafty on the process of learning.

Since, therefore, the end of human life is beatitude, which consists in the full cognition of divine truths, it is necessary that human life be directed to this beatitude by an initial possession of divine truths by faith, truths which man can hope to know fully in the ultimate state of human perfection.

Certain of these truths that must be known can be attained by reason even in this life: however, although knowledge of them is possible and even possessed by certain men, nevertheless faith is necessary for five reasons, which Rabbi Moses enumerates:

1. First, on account of the depth and subtlety of the matter, by which divine truths are hidden from human understanding. Therefore, lest any man be without some knowledge of them, provision is made that through faith, at least, he know divine truths. Therefore, in Eccles. 7:25 it is said: “It is a great depth, who shall find it out?”

2. Secondly, on account of the weakness of the human intellect from the beginning. For perfection of knowledge does not belong to the human intellect except at the end; therefore, that it should at no time lack a knowledge of God, it requires faith by which it may accept divine truths from the very beginning.

3. Thirdly, because of the many preambles that are required for a knowledge of God according to reason. For this there is needed knowledge of almost all the sciences, since cognition of divine things is the end of them all. But few indeed would comprehend these preambulatory truths or investigate them completely. Therefore, lest large numbers of men should be left without knowledge of divine things, the way of faith has been provided by God Himself.

4. In the fourth place, many men on account of their natural constitution are unfitted for perfect intellectual investigation according to reason; therefore, that these might not lack knowledge of divine truths, the way of faith has been provided.

5. In the fifth place, because of numerous occupations with,which men are busied, it would be impossible for all of them to discover, by way of reason, necessary truth in regard to God, and on this account the way of faith has been established, both as regards things that might in some way be known and as regards those that required revelation in order that they be believed.

But in the case of certain divine truths, for a complete understanding of them the human mind in no way suffices, but full knowledge of them is to be awaited in that future life when there will be complete beatitude: such is the truth of the Trinity and the unity of one God; and man is led to knowledge of this, not in accordance with anything due his nature, but by divine grace alone. Therefore it is necessary that, for a perfection of knowledge of this kind, certain suppositions be proposed which must be believed at first, and from these one is directed into full cognition of those truths which at the outset he held on faith, even as in other sciences also, as has been said. Hence in Is. 7:9 it is said, according to one translation: “Unless thou hadst believed, thou wouldst not understand.” And suppositions of this sort are those that must be believed by all, since in this life they are neither known nor understood by, any one.

Answers to objections

1. It may be said: Although matters of faith considered according to man’s natural powers are above him, they are not above man when he is illuminated by divine light; hence it is not necessary for man that he seek out such truths by his own power, but it is necessary for him to know them by divine revelation.

2. It may be said: God, in the first creation of things, established man as perfect in accordance with the perfection of his nature, and this consisted in the fact that man had all things due to his nature. But over and above that due to nature there were added afterward to the human race certain other perfections owing their source to divine grace alone, and among these was faith, as is evident from Eph. 2:8, where it is said of faith that it is “the gift of God.”

3. It may be said: For anyone striving to attain beatitude it is necessary to know in what he ought to seek this beatitude, and in what way. But this, indeed, can be done in no easier way than through faith, since investigation by reason cannot attain to such knowledge except after a previous knowledge of many other things, things not easy to know. Nor can one attain to such knowledge without danger, since human investigation, because of the weakness of our intellect, is prone to error; and this is clearly shown by reference to those philosophers who, in attempting to find out the purpose of human life by way of reason, did not find in themselves the true method, and so fell into many and shameful errors; and so greatly did they differ among themselves that scarcely two or three among them all were in agreement on any one question; yet, on the other hand, we see that by faith many peoples are brought to the acceptance of one common belief.

4. It may be said: Whenever there is acceptance of a truth, by whatever mode of assent, there must be something which moves the mind to assent: just as the naturally possessed light of the intellect causes assent to first principles, and the truth of those first principles causes assent to conclusions made from them; while in other ways we assent to things of which we have an opinion, though, if motives were a little stronger, they would incline us to belief, in so far as faith is said to be opinion. But that which inclines the mind to assent to the first principles of understanding or to conclusions known from these principles is a sufficient induction which forces assent, and is sufficient to judge of those things to which the mind gives its assent. On the other hand, whatever inclines one to form an opinion, even though with a good amount of conviction, is not that sufficient form of induction whereby assent is forced, nor by reason of it can there be perfect judgment of the things to which assent is given. Therefore also in faith by which we believe in God, not only is there acceptance of the truths to which we give assent, but also something which inclines us to that assent; and this is the special light which is the habit of faith, divinely infused into the human mind. This, moreover, is more sufficient for inducing belief than any demonstration, for, though from the latter no false conclusions are reached, still man frequently errs in this: that he thinks something is a demonstration which is not. The light of faith is also more sufficient than the natural light of reason by which we assent to first principles, since this natural light is often impeded by bodily infirmity, as is evident in the case of the. insane. But the light of faith, which is, as it were, a kind of impression of the First Truth in our minds, cannot fail, any more than God can deceive us or lie; therefore this light suffices for making judgment.

This habit of faith, nevertheless, does not move us by way of intellectual understanding, but more by way of the will; therefore it does not make us comprehend those truths which we believe, nor does it force assent, but it causes us to assent to them voluntarily. And thus it is evident that faith comes in two ways: namely, from God by reason of the interior light which induces assent, and also by reason of those truths which are proposed exteriorly and take their source from divine revelation. These latter are related to the knowledge which is oi faith as things known by the senses are to knowledge of first principles, because in both cases there is a certain determination given to cognition. Therefore, as cognition of first principles is received by way of sense experience, and yet the light by which those principles are known is innate, so faith comes by way of hearing, and yet the habit of faith is infused.

5. It may be said: To live in accordance with reason is the good of man inasmuch as he is man. Now, to live apart from reason, according to one meaning, can be understood as a defect, as it is in those who live according to sense; and this is an evil in man. But in another way, it may mean to live above reason as when, by divine grace, a man is led to that which exceeds reason: and in this case, to live apart from reason is not an evil in man, but a good above that which is human. And such is the cognition of truths of faith, although faith itself is not in every way outside reason; for, it is the natural reason which holds that assent ought to be given to truths declared by God.

Article 2

Whether Faith Should Be Distinguished from Religion


1. It seems that faith ought not to be distinguished from religion, because, as Augustine says in Ench., “God is to be worshiped by faith, hope, and charity”; but worship of God is an act of religion, as is evident from the definition of Tullius, which says: “Religion is that which offers to a superior nature, which men call divine, worship and ceremony”; therefore faith pertains to religion.

2. Augustine says in De vera religione: The true religion is that by which the one God is honored and known with a most unsullied piety or purity.” But to know God is a thing which belongs to faith; therefore, faith is contained under religion.

3. To offer sacrifice to God is a function or act of religion, but this pertains to faith, as Augustine says in IV De civ. Dei: “True sacrifice is any work done in order that we may adhere to God in holy association”; but the first adherence of man to God is by faith; therefore faith pertains principally to religion.

4. In John 4:24 it is said: “God is a Spirit, and they that adore Him, must adore Him in spirit and in truth.” Now, God is adored more when one submits his intellect to Him than when a bodily prostration is made; but through faith the intellect is submitted to God, since it subjects itself entirely in assenting to the truths revealed by God; therefore faith pertains especially to religion.

5. Every virtue having God as its object is a theological virtue: but religion has God as its object, since it is nothing else than the offering of due reverence to God; therefore it is a theological virtue. But it appears to belong more to faith than to any of the others, since only those are said to be outside the Christian religion who are outside [i.e., without] faith; therefore religon seems to be the same as faith.

Sed contra

On the contrary is what Tullius says in II Veteris Rhetoricae, where he makes religion a part of justice, which is a moral virtue. Therefore, since faith is a theological virtue, religion is of a genus other than that of faith.

Again, religion consists also in activity regarding the neighbor, as is evident in Jas. 1:27: “Religion clean and undefiled before God and the Father is this: to visit the fatherless and widows in their tribulation”; faith has no act except that which is referred to God; therefore religion is altogether distinct from faith.

Again, those are commonly called “religious” who are bound by special vows, but they are not the only ones called 1. the faithful.” Since, therefore, one of the faith and a religious are not the same thing, faith and religion are not the same.

Response. I answer that it must be said that, as is evident from Augustine (X De civ. Dei), theosebia, which the worship of God is called, includes as pertaining to it in the same way, religion, piety and latria, since all have as their purpose the worship of God. Reverence paid to anything, however, seems to be nothing else than a due operation performed with regard to it; and consequently men are said to cherish in various ways their fields, their parefits, their country, and other like things because different works are fitting to each. But God is not “cherished” in this same way: that any operation of ours would be of benefit or assistance to Him, as in the case of the above-mentioned instances; but it implies only that we submit ourselves to Him and show ourselves to be His subjects. Therefore this reverence which is absolutely divine is designated by the name of theosebia. But religion implies a certain “binding, back” according to which man obliges himself in some manner to this worship of God; wherefore Augustine says in his book, De vera religione: “The word ‘religion’ is thought to be derived from the religare (‘to bind back’), or from recte eligere (‘to choose rightly’),” as is said in IV De civ. Dei. For it is by proper choicethat a person binds himself to do something that must be done. We must also reelect those things which by negligence we have lost, as he also says. Therefore it is that those who consecrate their whole lives and themselves to the service of God by certain vows are called religious; but piety regards the mind of the worshiper, that it be not insincere or moved by desire of gain.

Since also a certain divine veneration, as it were, is due to those above us, even the acts of kindness which are done for the unfortunate are in a way sacrifices to God, according to the last part of the Epistle to the Hebrews (13: 16): “And do not forget to do good and to impart: for by such sacrifices God’s favor is obtained.” Hence it is that the name of piety and of religion are transferred to works of mercy, and especially to benefits done to parents and country. But latria implies a reverence that is of obligation, or worship in its essence; and this is so because we are, indeed, the subjects of Him whom we honor, not after the manner in which one man is said to be the servant of another, because of some accidental debt to him, but because all that we are we owe to Him as our Creator. Therefore latria is not any kind of service, but that by which man acknowledges his subjection to God. Thus, therefore, religion consists in an operation by which man honors God by submitting to Him; and this operation ought to be in harmony with Him who is honored, and with the one offering homage.

Now since He who is reverenced is a spirit, He cannot be approached by the body, but only by the mind; and so worship of Him consists chiefly in acts of the mind by which the mind itself is ordained to God. These acts are principally those of the theological virtues; and in accordance with this, Augustine says that God is worshiped by faith, hope, and charity, to which are added also the acts of the gifts ordained toward God, such as those of wisdom and of fear.

But because we who honor God are also possessed of bodies and receive our knowledge through bodily senses, there is the necessity that certain physical actions accompany the worship of God, not only that we may render service to God with our whole being, but also that by these bodily actions we may arouse in ourselves and in others acts of the mind ordained to God. Wherefore Augustine says in his book, De cura pro mortuis habenda: “Those who pray make the members of their bodies conform to their acts of supplication when they genuflect, extend their hands, or prostrate themselves upon the ground, or perform any other visible action; and although it is their invisible will and the intention of the heart that is known to God, it is not unseemly that the human soul should so express itself, but rather by so doing man stirs himself to pray and to lament his sins the more humbly and fervently.”

Hence, all acts by which man subjects himself to God, whether they are acts of mind or of body, pertain to religion. But because those things that are rendered to the neighbor on account of God are rendered to God Himself, it is evident that they also pertain to this same subjection in which religious worship consists; and so to one diligently considering the matter it is apparent that every good act pertains to religion. Hence Augustine says (loc. cit.): “True sacrifice is every work done that we may adhere to God in holy companionship; however, in a certain order.” First and foremost, those acts of the mind ordained to God pertain to the worship which we are speaking of. Secondly, there are acts of the body intended to arouse reverence of mind or to give expression to it, such as prostrations, sacrifices, and the like. Thirdly, there also pertain to divine worship all other acts ordained to the neighbor for the sake of God.

Nevertheless, as magnanimity is a certain special virtue, although it uses the acts of all virtues, since it bestows a grandeur in the exercise of them all and so regards its object under a certain special aspect; so also religion is a special virtue in the acts of all the virtues, considering a special aspect of its object, namely, that which is due to God; and thus it forms a part of justice. There are, moreover, special acts assigned to religion, which pertain to no other virtue, such as prostrations and the like, in which the worship of God consists secondarily.

From this it is evident that acts of faith pertain, indeed, materially to religion, as do the acts of other virtues, and the more so inasmuch as acts of faith are the first motions of the mind toward God; but formally faith is distinguished from religion, as regarding another aspect of its object. Faith agrees with religion also because faith is the cause and principle, of religion. For no one would elect to manifest reverence to God unless by faith he held that God was the Creator, Ruler, and Rewarder of human actions.

Nevertheless religion is not a theological virtue: for it has as its matter all acts, as those of faith or ‘of any other virtue inasmuch as these are offered as due to God; but it has God as its end. For to worship God is to offer acts of this kind as due to God.

From what has been said, the response to all the objections is evident.

Article 3

Whether the Christian Religion Is Aptly Called Catholic or Universal


1. It seems that the Christian religion ought not be called Catholic, because knowledge must be proportionate to the knowability of a thing. Now an indefinite thing is not known in any way at all: but faith is a knowledge of God who is neither universal nor particular, as Augustine says in his book, De Trinitate; therefore this religion cannot be called universal.

2. One can have only singular knowledge about singular things; but by faith we hold the truth of certain singular facts, as the Passion and Resurrection of Christ, and the like; therefore the Christian faith cannot be called universal.

3. From what is common to many, it is not permissible to impose a name as proper to any one of them, since a name is given in order that a thing may be known as distinct: but every school or sect proposes certain things that must be universally held by all its followers, or certain doctrines that must be universally affirmed as true; therefore the Christian religion has no special right to be called Catholic.

4. Idolatry extends to every corner of the earth; but the Christian religion has not yet been brought to all the regions of the world, since there are yet some barbarians who do not know the faith of Christ; therefore these idolatrous sects, rather than the Christian religion, deserve the name of Catholic.

5. What does not include all should not be called universal; but the Christian religion is not accepted by many; therefore it is inaptly called universal or Catholic.

Sed contra

On the contrary is that which Augustine says in De vera religione: “The Christian religion must be held by us, and the communication of that Church which is catholic and which is called Catholic, not only by its own members, but even by its enemies.”

Again, universal and common appear to be the same; but the Christian faith is called the common faith by the Apostle (Titus 1:4): “To Titus, my beloved son according to the common faith”; therefore it is rightly called Catholic.

Again what is universally proposed to all should in a special way be called universal; but the Christian faith is universally proposed to all, as is evident in the last chapter of Matthew (28:19), “Teach all nations,” etc.; therefore it is deservedly called Catholic or universal.

Response. I answer that it must be said that faith, just as any other cognition, has a twofold matter: namely, that in which it exists (the believers themselves) and that about which it is concerned (the truths believed); and as regards both types of matter, the Christian religion can be called Catholic.

As regards the believers it is Catholic because the Apostle (Rom. 3:2) asserts that that is the true religion which was given testimony to by the law and the prophets. Since, however, in the times of the prophets various tribes offered worship to different gods, only one nation, the people of Israel, gave due honor to the true God, and so there did not exist that one universal religion which was foretold to them by the Holy Spirit, that worship of the true God which would be paid by all. Therefore Isaias (45:24) says: “For every knee shall be bowed to Me, and every tongue shall swear.” And this prophecy has, indeed, been fulfilled by faith and the Christian religion.

Therefore deservedly is that faith called Catholic since it has been accepted by men of every condition. And thus, those who have fallen away from this faith and this religion which has been so universally foretold and received, and who have become divided into various sects, are not called Catholics, but as it were, having been cut off from the communion of the faithful, they are called heretics.

As regards the truths proposed for belief in the Christian religion, there is also found truth that is catholic. Now, there were various arts and ways in ancient times according as there was vision, or belief in the vision of the human mind among men. For certain men placed the good of man in corporeal things alone, either in riches or in honors or in pleasures. Some others placed this good in the soul alone, as in moral or intellectual virtues. Certain others, as Augustine says in his book, De civ. Dei, thought that gods ought to be honored because of the corporeal blessings of this life; but others, on account of blessings to be realized after death. Porphyry also relates that it was believed among certain peoples of the earth that the imaginative part of the soul would be cleansed, but not the whole soul; and he said, as Augustine tells in X De civ. Dei, that there had not yet been found a single sect that possessed a universal way for liberty of spirit. Now this way, as Augustine says in the same place, is the Christian religion.

This religion teaches that God is to be honored not only on account of eternal, but also because of temporal benefits; that He rules man not only in spiritual ways but also in all that concerns him bodily, and that He promises beatitude for both soul and body. Hence His regulations are called universal, as pertaining to the whole life of man and as extending to all that in any way affects man. For these two reasons, therefore, thename “universal” is given to the Christian religion, as Boethius in the text makes clear.

Answers to objections

1. It may, therefore, be answered: Although God is in Himself neither universal nor particular, yet He is the universal cause and end of all things, and thus knowledge which is held concerning Him is universal since it extends to all things.

2. It may be said: Faith holds these particular facts as universal remedies for the healing and the liberation of the whole human race.

3. Answer may be made: Other sects claim for themselves what is proper to the Christian faith, but they cannot vindicate this claim; therefore, the name of universality does not properly belong to them.

4. It may be said: Idolatry was no one form of religion, but differed among various peoples, since they set up for themselves various gods to be worshiped. Nor again, were those forms of idolatry accepted by all nations, since they were rejected by those who honored the true God, and even by the philosophers of the Gentiles, who said that certain religious ceremonigeought to be observed since they were commanded by law, but not because they could be known to please the gods, as Seneca said, according to Augustine in De civ. Dei.

5. It may be answered: The Christian religion is not called Catholic on account of individual nations who adhere to it, but on account of the body of individual men from all conditions of mankind who adhere to it.

Article 4

Whether it Is a True Article of Faith, That the Father, Son, and Holy Spirit Are One God


1. It seems that it is not the confession of the Catholic,faith that Father, Son, and Holy Spirit are one God: because, as Boethius himself says, upon inequality there follows plurality of gods. But the Catholic Scripture, which is the head of the Catholic religion, as Augustine says in De vera religione, states that there is inequality between Father and Son, as is evident from what is said in the person of the Son in John 14:28: “The Father is greater than I.” Therefore what is said is not the confession of the Catholic religion.

2. 1 Cor. 15:28 says: “And when all things shall be subdued unto Him, then the Son also Himself shall be subject unto Him that put all things under Him, that God may be all in all.” And so the conclusion is like the former.

3. Prayer is not made except by an inferior to a superior: but the Son prays for us. Rom. 8:34, “Christ Jesus... who also makes intercession for us.” Likewise of the Holy Spirit it is said in the same place (8:26), “The Spirit Himself asks for us with unspeakable groanings.,” Therefore the Son and the Holy Spirit are inferior to the Father according to the confession of the Catholic faith, and so the conclusion is the same.

4. John 17:3 gives the words of the Son addressing Himself to the Father: “That they may know You, the only true God, and Jesus Christ, whom You have sent.” Therefore the Father alone is the true God, and not the Son and the Holy Spirit. Therefore they seem to be creatures, and so the same conclusion is reached.

5. In 1 Tim. 6:15, the Apostle says: “Which in His times He shall show, who is the Blessed and only Mighty, the King of kings, and Lord of lords. Who only has immortality and inhabits light inaccessible.” Therefore all these titles belong only to the’Father, and so the conclusion is as before.

6. In Mark 13:32 it is said: “But of that day or hour no man knoweth, neither the angels in heaven, nor the Son, but the Father.” Therefore the Father’s knowledge is greater than that of the Son. Consequently His essence also is greater, and thus the conclusion is the same.

7. Matt. 20:23 says: “To sit on My right or left hand, is not Mine to give to you, but to them for whom it is prepared by My Father.” Therefore the power of the Son is not equal to that of the Father.

8. In Col. 1:15, it is said of the Son that He is “the firstborn of every creature.” But this comparison would not be made unless of beings of one genus; therefore the Son is a creature.

9. In Sirach 24:14 it is said in the person of divine Wisdom, “From the beginning, and before the world, was I created.” Thus the conclusion is the same.

10. He who is revealed is less than he who reveals; but the Son is revealed by the Father, as is evident in John, chap. 12; therefore, the Son is less than the Father.

11. The one sending is greater than the one sent. But the Father sends the Son, as is clear from Gal. 4:4, “God sent His Son,” etc. And He also sends the Holy Spirit, according to John 14:26, “The Paraclete, the Holy Spirit, whom the Father will send in My name.” Therefore the Father is greater than the Son and the Holy Spirit. And thus the aforesaid doctrine does not seem to be in accordance with the Catholic faith.

Sed contra

But on the contrary it is said in John 1:1, 3: “In the beginning was the Word, and the Word was with God, and the Word was God.... All things were made by Him,” etc. From this it is to be held that the Son is eternal, for otherwise He could not have been in the beginning: and that He is equal to the Father, for otherwise He would not be God: and that He is not a creature, for otherwise all things would riot have been made by Him.

Again, since the Son is truth, He could not lie concerning Himself. But the Son said that He was equal to the Father (John 5: 18): “He also said God was His Father, making Himself equal to God.” Therefore He is equal to the Father.

Again, Phil. 2:6 says: “He thought it not robbery to be equal with God.” But it would have been robbery if He thought that was so which was not. Therefore He is equal to God.

Again, John 10:30, “I and the Father are one.” And John 14:11, “I am in the Father, and the Father in Me.” Therefore one is not greater than the other.

Again, Rom. 9:5: “And of whom is Christ, according to the flesh, who is over all things, God blessed forever.” Therefore no one is superior to Him; and thus He is not less than the Father.

Again, 1 John 5:20, “And we know that the Son of God is come: and He hath given us understanding that we may know the true God, and may be in His true Son. This is the true God and life eternal.” Therefore He is not less than the Father.

Again, it is shown that the Holy Spirit is the true God and equal to the Father by what is said in Phil. 3:3, according to the Greek text. “We are the circumcision, who serve God the Spirit”, and in regard to this service, that of latria is understood, as is evident in the Greek. And such honor is due to no creature. Deut. 6:13 and Matt. 4:10: “The Lord your God you shall adore, and Him only you shall serve.” Therefore, the Holy Spirit is not a creature.

Again, the members of Christ cannot be the temple of anyone who is less than Christ: but our bodies, which are members of Christ, according to the Apostle, are temples of the Holy Spirit, as is said in 1 Cor. 6: 19. Therefore the Holy Spirit is not less than Christ, or less than the Father; and thus it is true, as the author says, that this is a doctrine of the Catholic religion.

Response. I answer that it must be said that the position of the Arians, which establishes inequality among the divine persons, is not a confession of the Catholic religion, but rather an impiety of the Gentiles, as is thus evident.

Among the Gentiles all immortal substances are called gods. Among these, moreover, they hold, or rather the Platonists hold, that there are three principal persons, as is made clear by Augustine in De civitate Dei (Bk. X), and by Macrobius on the Somnium Scipionis, namely, the God, who is the Creator of all things, whom they call also the Father, since all things have their source in Him; and, secondly, a certain inferior substance, whom they call the Paternal Mind or the Paternal Intellect, who contains the ideas of all things, and who is made by God the Father, they say; and thirdly, after Him they suppose a Soul-of-the-World, a spirit who is, as it were, the life of the whole world. And these three substances they name as their chief gods, and as the three principles by which souls are purified.

Origen, moreover, following the teachings of the Platonists, thought that after the same manner the doctrine of the true faith ought to be interpreted, because it is said, “There are three who give testimony in heaven” (1 John 5:7). And so, as the Platonists supposed that there were three principal substances, Origen held that the Son was a creature and less than the Father, in that book which is entitled Peri Archon (“Concerning the Principles”), as is made clear by Jerome in a certain epistle regarding the errors of Origen. And since Origen himself taught at Alexandria, Arius drank in his error from the things he wrote. On this account Epiphanius says that Origen was the father and font of Arius.

Therefore the position of the Christian and Catholic faith regarding the Trinity differs as much from the position of Arius as does the error of the Gentiles, which, in calling creatures gods, rendered to them the service of divine praise. This the Apostle (Rom. 1:25) criticizes when he says, “They worshiped and served the creature rather than the Creator.”

Answers to objections

1. It may be said: As Augustine states in II De Trinitate, passages found in the Scriptures in regard to the Father and the Son are threefold.

a) First, some show a certain unity of substance and equality of persons, as, “I and the Father are one” (John 10:30).

b) Other passages show the Son to be less because of His having the form of a servant, according as He made Himself less, as is said in Phil. 2:7, “He emptied Himself, taking the form of a servant.”

c) Certain things are also said that show Him to be neither less nor the equal of the Father, but only that the Son is from the Father, as in John 5:26, “As the Father has life in Himself, so He hath given to the Son also to have life in Himself.”

The first authoritative passages are used by Catholics in making a defense of the truth. But those of the second and third kind are employed by heretics in confirmation of their error, though in a vain attempt. For the things that are stated of Christ according to His human nature should not be referred to His divinity; otherwise it would follow that His death, which is recorded of Him according to His humanity, would be according to His divinity. Likewise, neither is it shown that the Son is less than the Father, although the Son is from the Father, because the Son has from the Father all that the Father possesses, as is held in John 16, and Matthew 11. Wherefore no inequality of divinity can be asserted because of the order of origin.

When, therefore, it is said, “The Father is greater than I,” this is said of the Son according to His human nature and not according to His divine nature, as Augustine maintains; or, as Hilary says, according to His divine nature in such a way that “greater” does not imply inequality (because the Son is not less than the Father, inasmuch as to Him is given a name above all names); but it implies dignity of a principle inasmuch as it is from the Father that the Son possesses that by which He is the equal of the Father.

2. It may be said: All things the Father not only subjected to the Son, but the Son Himself made them subject to Himself, according to the saying of Phil. 3:21: “According to the operation whereby also He is able to subdue all things unto Himself,” i.e., according to the Divinity which is equal in Him to that of the Father. Wherefore, when it is said that Christ will be subject, this does not imply relation of the Son to the Father according to Divinity, but rather the relation of the human nature of the Son to the Divinity of the Father, which Divinity is common to the whole Trinity.

And when the divine nature shall be perfectly known, then it will be apparent that especially according to His human nature He is subject to the divine nature; but not with such a subjection as that which certain heretics claim who say that the very human nature which was assumed by the divine nature is transmuted into it, but rather that He is less than the Father by reason of His humanity. This is made especially clear by the fact that He will deliver His kingdom, that is, the faithful, to the Father, not claiming them for Himself, but leading them to the vision of the Father, a vision in which His own Divinity also will be seen.

3. It may be answered: According to Augustine (III De Trinitate), inasmuch as the Son prays He is less than the Father; but inasmuch as He obtains hearing with the Father, He is the equal of the Father.

But the Holy Spirit is said to intercede for us inasmuch as He causes us to make intercession and renders our prayers efficacious.

4. It may be said: According to Augustine (VI De Trinitate), the statement that there is one only true God must not be interpreted to refer to the Father alone, but as including Father, Son, and Holy Ghost simultaneously; and they are said to be, the one true God because no being outside the Trinity is true God. Wherefore, it must be in this way that one understands: “That they may know You, the only true God, and Jesus Christ whom You have sent” (John 17:3). For there is one only true God, and no mention is here made of the Holy Spirit, because, since He is the nexus of the other two Persons, He is understood by mention of the other two.

5. It may be answered: According to Augustine (I De Trinitate), this saying is not to be understood of the Person of the Father alone, but of the entire Trinity. For the whole Trinity is blessed and powerful, and the whole Trinity shows forth the Son. Even if He did say: “He shall show, who is the Blessed and only Mighty,” etc., this would not indicate that the Son is separate from the Father, or that the Father is considered as being separated from the Son, because it is said in Sirach 24:8, in the person of the Son, who is the Wisdom of God, “I alone have compassed the circuit of heaven.” This is said, therefore, because in those things which pertain to the essence of God, Father and Son are altogether one, and hence what is said of one of them by diction which may be exclusive does not imply any mutual separation, but only their separation from creatures.

6. It may be said: The Son knows “that day and hour,” not only according to His divine nature, but even according to His human nature, since His soul knows all things. Hence He is said not to know that day, as Augustine explains in I De Trinitate, because He does not make it known to us; wherefore He said to those questioning Him: “It is not for you to know the times,” etc. (Acts 1:7). And in the same way the Apostle says in 1 Cor. 2:2, “I judged not myself to know anything among you,” because he was unwilling to disclose lofty things to them since they lacked capacity to understand.

Or this may be understood as regarding the Son, not in His character as head of the Church, but in the person of His members, since the Church, as Jerome says, is without knowledge of these truths. However, in saying that the Father alone knows them, it is evident that the Son also knows them, according to the aforesaid reason.

7. Answer may be made: As Augustine says in I De Trinitate, the verse: “It is not Mine to give to you,” etc., must be understood to mean that it is not in the power of human nature to give this, so that He may be known to grant it by reason of the fact that He is God and equal to the Father.

8. It may be said: According to Augustine, I De Trinitate, many heretics, not understanding this point of apostolic doctrine, broke out into insult of the Son of God, saying and declaring that He was a creature, having little regard for the import of words. For He is said, indeed, to be the first begotten, but not the first created, so that He might be believed to have been begotten, according to His divine nature, and to be first on account of His perpetuity. Moreover, although the Son belongs to no genus of creatures, yet, as Basil holds, He has something in common with creatures: namely, the fact that He received from the Father that which He has; but this possession is superior to that of creatures, since through His own nature He possesses what He receives from the Father. On this account there can be noted a certain order between the generation of the Son and the production of creatures.

9. It may be said: This saying and all sayings similar to it, which are read in regard to the wisdom of God, ought to be referred to the wisdom of creatures, such as the angels, or to Christ Himself according to His human nature. Thus His wisdom is said to be “from the beginning,” or “at the beginning of creation,” as if from eternity it predestined that creation should belong to Him.

10. Answer may be made: As Augustine says in II De Trinitate: From the fact that the Father will glorify the Son, it does not follow that the Son is inferior to the Father; otherwise, He would be less than the Holy Spirit, because the Son says of the Holy Spirit in John 16:14: “He shall glorify Me.” Now, this glorification refers not to the Person of the Son, but to the fact that in the knowledge of men He will be glorified, since the Spirit will make Him known; or it may be referred to the body which He had assumed and to the glory of the Resurrection.

11. It may be said: The Son and the Holy Spirit are said to be “sent” by the Father, not that they now are where they had previously not been; but that, they are now there in a certain manner in which they had not previously been: that is to say, as regards a certain effect in creatures. Wherefore, when the Son and the Holy Spirit are said to have been sent by the Father, no inequality in the Trinity is revealed, but an order of origin, by which one Person is from another. Therefore the Father is not “sent,” because He is not from another in such a way that He has from another His efficacy in relation to any of His effects; and it is in this way that a divine Person is “sent.”


Concerning Those Things That Pertain to the Cause of Plurality

Inquiry is made of those things that pertain to the cause of plurality. And this inquiry involves four questions:

1. Whether otherness is the cause of plurality.

2. Whether variety of accidents produces diversity according to number.

3. Whether two bodies can be, or can be thought of as being, simultaneously in the same place.

4. Whether difference of location exerts some influence as to difference according to number.

Article 1

Whether Otherness Is the Cause of Plurality


1. It seems that the cause of plurality cannot be otherness. For as is said in the Arithmetica of Boethius, all things whatever of the sum-total of beings that have been established in nature seem to ‘ have been formed by reason of numbers. For this was the principal exemplar in the mind of the builder of the universe: and this is in agreement with what is said in Wis. 11:21, “You have disposed all things in weight and in number and in measure”. Therefore plurality or number is first among created things, and no cause of it is to be sought for.

2. As said in the book De causis, the first of created things is being; but being is divided at first by one and many; hence nothing can exist as prior to multitude except being and unity. Therefore it does not seem to be true that anything else should be its cause.

3. Plurality either includes all genera according as it is distinguished from unity, which is convertible with being: or it is itself in the genus of quantity, according as it is distinguished from that unity which is the principle of number. But otherness is in the genus of relation, and relations are not causes of quantities, but rather the converse is true. Much less, then, is relation the cause of what is in every genus, because in that case it would be the cause of substance; therefore otherness can in no way be the cause of plurality.

4. For contrary things there are contrary causes: but identity and otherness or diversity are opposites; therefore they have opposite causes. But unity is the cause of identity, as is evident in V Metaph.; therefore plurality or multitude is the cause of diversity; and consequently otherness is not the cause of plurality.

5. The principle of otherness is accidental difference; for differences of this kind, according to Porphyry, make a thing other. But accidental difference is not found in all things in which there is plurality; in fact, in some cases there is no difference of any kind. Certain things, such as simple forms, cannot be subjects of accidents; and there are other things that agree in no way, so that they cannot be called different, but diverse, as is evident by the words of the Philosopher in X Metaph. Therefore otherness is not the cause of all plurality.

Sed contra

But on the contrary is what Damascene says, that division is the cause of number; but division consists in diversity or otherness; therefore diversity, or otherness, is the principle of plurality.

Again, Isidore says that number is called, as it were, the master of numeration, that is, of division; and so the conclusion is like the first.

Again, plurality is not constituted except by recession from unity; but there is no loss of unity except by division, since a thing is said to be one in that it is undivided, as is evident from X Metaph.; therefore division constitutes plurality, and thus the conclusion is as before.

Response. I answer that it must be said, as the Philosopher states in X Metaph., that a thing is said to be plural (many) from the fact that it is divisible or has been divided. Wherefore anything that is the cause of division ought to be regarded as a cause of plurality.

Now, the cause of division cannot be considered the same in posterior and composite beings as in those that are first and simple. For in’posterior and composite things, the cause of division which is, as it were, the formal cause of division by reason of which division comes about, is diversity found in more simple and primary beings, as is made clear in the case of division according to quantity. For one part of a line is divided from another part by the fact that they have each a different place, which is, as it were, the formal difference of a thing of continuous quantity having position. It is also evident in the division of substances. For man is different from an ass because he has diverse constitutive differences: but the diversity by which posterior, composite beings are divided according as prior and simpler beings are, presupposes plurality of these same primary and more simple beings. For the reason why man and ass have diverse differences is that ratipnality and irrationality are not one and the same thing, but differ in many ways. Nor can it be said endlessly that the plurality of one thing is owing to another diversity in another prior and simpler cause, because thus we would go on to infinity. Therefore it is necessary in some other way to assign a cause of plurality and division in prior and more simple beings.

Now, there are some beings of this kind divided in themselves. Nevertheless it cannot be that being is divided from being, inasmuch as it is being: for nothing is divided from being except non-being. Likewise also from this-being, this-being is not divided, unless in this-being there is included negation of the same being. Wherefore in primary termini of thought negative propositions are immediately, as it were, negations, one of the other, in the intellect. For the first thing caused constitutes plurality with its cause, which does not reach to it [so as to be identical with it]. And according to this, certain philosophers hold that plurality is caused in a certain order from one and the selfsame thing; so that from one thing proceeds, at first, one being, which with its cause constitutes a plurality, and from this plurality, now two things can proceed, one according to the thing itself, and the other according to its conjunction to a cause. But we are not forced to say this, since one thing might be able to imitate the first in some way in which the second would fail to agree with it; and this defect could be imitated in another; and so there can be found many effects of the first cause in any number of which there is both negation of the cause and negation of the effects in the same way, or according to distance separating one from the other.

So, therefore, it is evident that the first reason or, principle of plurality or division is from affirmation and negation, as the order of origin of such plurality is understood, because first there must be understanding of being and non-being, by which first divisions are constituted, and by this, there are the many.

Hence, just as first being, inasmuch as it is undivided, is immediately recognized as one, so after division of being and non-being there is immediate recognition of the plurality of first simple beings. The nature of diversity, moreover, follows upon plurality according as there remains in it the virtue of its cause, that is, the opposition of being and nonbeing. Therefore one of many diverse things is said to be related to another because it is not that other. And since a second cause does not produce its effect except by virtue of a first cause, therefore the plurality of first causes does not make division and plurality in secondary, composite beings unless there remains in that plurality the virtue of prime opposition, which is between being and non-being, by reason of which it has the nature of diversity; and thus the diversity of first causes produces the diversity of second.

According to this, it is true, as Boethius says, that otherness is the principle of plurality. indeed, otherness is to be found in things because there is diversity among them. However, although division precedes plurality of first causes, diversity does not; because ‘ division does not require the being of things divided among themselves, since division is by affirmation and negation, but diversity does require each to be a distinct being; wherefore it presupposes plurality. Hence it is in no way possible that the cause of the plurality of first beings should be diversity, unless diversity is employed as meaning division.

Boethius, therefore, is speaking of the plurality of composite beings, as is evident from the fact that he presents a proof involving those things that are diverse according to genus or species or number, and these kinds of diversity exist only in composite beings. For anything which is in a genus must be composed of genus and difference. Those, therefore, who declare the Father and Son to be unequal make declaration of composition, at least according to reason, inasmuch as they say the Father and Son agree in this, that they are God, but differ in the fact that they are unequal.

Answers to objections

1. It may be said: In these words, number is shown to be prior to other created things, such as the elements and other such beings; but it is not prior to other notions, such as affirmation and negation or division and the like. Moreover, not every kind of number is prior to all created beings, but only number which is the cause of each thing, namely, God Himself, who, according to Augustine, is Number, giving species to every creature.

2. It may be answered: Plurality, commonly speaking, im,mediately follows upon being; but this is not necessarily true of all plurality, and so it is not unfitting that the plurality of posterior beings should be caused by the diversity of those that are prior.

3. It may be said: As one and many are not properly of one genus, so neither are the same and the diverse, but they are passiones of being inasmuch as it is being, and hence there is no difficulty if the diversity of certain beings causes the plurality of others.

4. It may be said: Some kind of plurality precedes all diversity, but diversity does not precede all plurality, yet some kind of diversity precedes certain plurality. Hence two things are equally true: namely, that, commonly speaking, multitude produces diversity, as the Philosopher says; and that diversity in composite things produces plurality, as Boethius here declares.

5. It may be answered: Boethius is using “otherness” in place of “diversity,” which is constituted by certain differences, whether they are accidental or substantial. But those beings that are diverse yet not different are first beings, and Boethius is here not speaking of them.

Article 2

Whether Variety of Accidents Produces Diversity According to Number


1. It seems that variety of accidents cannot be the cause of plurality according to number. For the Philosopher says in V Metaph. that those things are numerically one in which the matter is one; therefore they are numerically plural in which the matter is plural; therefore variety of accidents does not produce diversity in number, but rather diversity of matter does so.

2. As the Philosopher says in IV Metaph., the cause of the substance and of the unity in things is the same; but accidents are not the cause either of the substance or of the unity in the individual; consequently they cannot be the cause of numerical plurality.

3. All accidents, since accidents are indeed forms, are themselves communicable or common and universal: but nothing of this kind can be the cause of individuation in another, or a principle of individuation; therefore accidents cannot be principles of individuation. But certain things are diverse according to number inasmuch as they are divided in their own individuation; therefore accidents cannot be causes of diversity according to number.

4. As those things that are in a genus or a species differ according to their substance, and not only according to an accident, so also those things that differ according to number must do likewise; but certain things are said to be diverse in genus or in species by reason of what is in the genus of substance, and not according to their accidents; therefore, in like manner, things are said to be numerically diverse according to what is in the genus of substance, and not according to accidents.

5. If a cause is removed, so is its effect. Now it happens that every accident is removed from a subject either actually or by thought. If, therefore, an accident were the principle of plurality according to number and diversity, it would happen that the same things would sometimes be numerically one and sometimes diverse, either actually or by thought.

6. What is posterior is never the cause of what is prior. But among all accidents, quantity holds first place, as Boethius says in Lib. praedicam. Among quantities, however, number is prior since it is more simple and more abstract. Therefore an accident cannot be the principle of plurality according to number.

Sed contra

On the contrary is the statement made byy Porphyry, that a collection of accidents which are not to be found in another produces the individual. But what is the principle of individuation is the principle of numerical plurality; therefore accidents are the principle of plurality according to number.

Again, in the individual, there is found nothing except matter, form, and accidents. Diversity of form, however, does not produce diversity according to number, but according to species, as is said in X Metaph. Now, diversity of matter produces diversity of genus. For the Philosopher says in X Metaph. that those things differ in genus in which there is not common matter, or generation of one into the other (mutual generation). Therefore diversity according to number cannot be produced except by diversity of accidents.

Moreover, what is found as common in many things that are specifically different is not the cause of diversity according to number, because the division of genus into species precedes the division of species into individuals; but matter is found to be common in things that are different in species because the same matter is possessed by contrary forms, otherwise beings having contrary forms would not be transmuted one into the other; therefore matter is not the principle of individuation according to number, and neither is form, as has been noted at the beginning. Hence it remains that accidents are the cause of this kind of diversity.

Again, in the genus of substance there is found only genus and difference; but the individuals of one species differ neither in genus, nor by reason of substantial differences; therefore they do not differ except because of accidental differences.

Response. I answer: For the clarification of this question and of those other questions treated of in the text of Boethius, it is necessary to see what may be the cause of the threefold diversity spoken of in the text.

Now, since in the individual composite in the genus of substance there are only three things (matter, form, and the composite), it must be that in each of these things the causes of their diversities are to be found. Accordingly it must be evident that diversity of genus is reduced to diversity of matter; but diversity according to species is reduced to diversity of form; whereas diversity according to number is owing partly to diversity of matter, and partly to accidental diversity.

Since, moreover, genus is the principle for knowableness of a thing, inasmuch as it is the first part of a definition, though matter in itself is unknowable, it is not possible that from matter in se diversity of genus should be known, but only according to that mode by which it is knowable. Now, a thing is knowable in two ways. (1) In one way, by analogy, or by comparison, as is said in I Physic. Thus we say that this is matter or that matter is related to natural things as wood is to a couch. (2) In another way, a thing is known by the form because of which it has actual being. For everything is known inasmuch as it is in act, not according as it is in potency, as is said in X Metaph.

According to this aspect, diversity of genus derives from matter in two ways. (1) In one way, by analogous diversity in relation to form, and thus the first genera of things are distinguished according to matter. For what is in the genus of substance is referred to matter as to a part of itself; but what is in the genus of quantity has no matter as a part of itself, but is related to it as its measure, and quality is related as its disposition. And by means of these two genera (namely, quantity and quality), all other genera are diversely related to matter, which is a part of substance; hence substance has the nature of a subject and as such has a certain relation to accidents. (2) In another way, diversity of genus has its, origin in matter inasmuch as matter is perfected by form. And since matter is pure potency, just as God is Pure Act, to say that matter is perfected by act (which is form) is to say nothing else than that in some way it shares in a certain similitude to First Act, imperfectly indeed, since what is composed of matter and form is midway between pure potency and pure act.

Moreover, matter does not receive similitude to First Act in an altogether equal way, but in some things it is received imperfectly and in others more perfectly; thus, for example, some beings participate in a divine similitude inasmuch only as they subsist; others, in that they have knowledge; and still others, by possession of intellect. Therefore what is the similitude of First Act in any existing matter is its form. But in some beings this form causes it only to exist, in others to exist and to live, and so, in one and the same being, form may be the cause of other perfections. For what is the more perfect similitude has everything that less perfect similitudes have by way of perfections, and more besides. Something common, therefore, may be found in various similitudes, but possessed more imperfectly in some and more perfectly in cothers; just as matter may be subjected to both act and privation. And so matter, once taken together with this common element, is still material in regard to the aforementioned perfection and imperfection. From this material element it takes its genus, but its difference is from the perfection or imperfection of which we spoke above. For example, frorp this common material element (namely, having life), there is derived the genus “animated body”; but because of a superadded perfection there derives the difference “sensible,” while, on the other hand, from imperfection there is derived the difference “insensible.” Thus the diversity of such material things brings about diversity of genus, as that between animal and plant. On this account matter is said to be the principle of diversity according to genus, and in the same way, form is the principle of diversity according to species; because it is by reason of formal qualities which material things possess in addition to those which are the cause of their genus as material things, or by relation of form to matter, that the differences constituting species are derived.

However, it must be borne in mind that this “matter” whence genus is derived has in itself both form and matter. While the logician considers genus only according to its formal aspect, his definitions are said to be formal; but the natural philosopher considers genus from both aspects. Hence it sometimes happens that a thing shares in a logical genus in which it would not be classed according to the natural philosopher. Now, this happens when something by way of similitude to First Act is found in a material thing, and again in one without matter, and again in a being altogether different in matter. Thus it is evident that a stone which is in matter in such a way as to be potential to being, attains to something of similitude to First Act by being subsistent, and the sun also attains to the same similitude, though being in matter which is potential to place, but not any longer to being (having subsistent existence); and an angel likewise, although lacking any kind of matter. Hence the logician, finding in all these beings that from which a genus derives, places them all in the genus of substance; but the natural philosopher and the metaphysician, who considers the principles of things, not finding these all to be in material agreement, says that they differ in genus; as is said in X Metaph.: that corruptible and incorruptible differ generically and that those beings agree in genus whose matter is one and among which there is mutual generation.

Thus therefore it is evident in what way matter produces diversity in genus, and form produces diversity in species. But among individuals of the same species diversity should be considered, according to that laid down by the Philosopher (VII Metaph.); namely, that just as parts of genus and species are matter and form, so the parts of the individual are this matter and this form. Therefore, just as diversity of matter causes diversity in genus, or diversity of form causes diversity in species, absolutely, so this form and this matter produce diversity in number: but no form, as such, is of itself. I say, however, “no form, as such,” because of the rational soul, which in a manner is this something of itself, but not merely inasmuch as it is a form. Intellect, in truth, since it is a form capable of being received into anything—as its matter, or as its subject—can naturally be attributed to many; a thing which is contrary to the nature of that which is this something; hence it is, made a form by the fact that it is received in matter. But since matter, considered in itself, is indistinct, it is not possible that it would individuate a form received into it, except as it is distinguishable. For no form is individuated by the fact that it is received into’matter, except in so far as it is received into this matter, or it is this distinct form, determined to this, and at this time.

Moreover, matter is not divisible except by quantity. Therefore the Philosopher says in I Physic., that if quantity were removed, a substance would remain indivisible: hence matter is made to be this matter and is signate inasmuch as it exists under dimensions. Dimensions, however, can be considered in two ways.

1. In one way according to their termination, and I say that they are terminated according to limited measure and figure; and so, as complete beings, dimensions are classed in the genus of quantity, and thus they cannot be the principle of individuation: because such termination of dimensions may frequently vary in regard to the same individual, and in such case it would follow that the individual would not remain numerically the same.

2. In another way, dimensions may be considered without this certain determination, merely in the nature of dimension, although they never could exist without some kind of determination; just as the nature of color cannot exist without determination to white or black; and according to this aspect dimensions are classed in the genus of quantity as imperfect. And by these indeterminate dimensions matter is made to be this signate matter, and thus gives individuality to a form, and thus also by matter there is caused the numerical diversity of things in the same species.

Therefore it is evident that matter, according as it is considered in itself, is not the principle of diversity, either according to species or according to number; but as it is the principle of generic diversity inasmuch as it is considered the subject of a common form, so it is the principle of numerical diversity inasmuch as it is considered as subject to indeterminate dimensions. Therefore also, since these dimensions are in the genus of accidents, diversity according to number is reduced to diversity of matter, or to accidental diversity, according to the nature of the aforesaid dimensions. Other accidents, however, are not principles of individuation, but they are the principle of knowing the individual to be distinct. In this way individuation is also attributed to other accidents.

Answers to objections

1. It may be said: When the Philosopher says that those things are numerically one in which the matter is one, this must be understood of signate matter which is the subject of dimensions; otherwise it would be necessary to say that all generable and corruptible things are numerically one, since their matter is one.

2. It may be answered: Since dimensions are accidents, they cannot per se be the principle of the unity of an individual substance; but matter, inasmuch as it underlies such and such dimensions, is understood to be the principle of this unity and of this multitude.

3. It may be said: It is according to the nature of an individual thing that it be undivided in itself, and divided from other things by an ultimate division. No accident, however, has in itself the proper nature of division, unless it is quantity; therefore dimensions of themselves have a certain nature of individuation according to a determined place, inasmuch as place is a difference of quantity. Thus there is a twofold meaning of individuation: the one on the part of a subject, and this is the same for any accident; the other meaning, on the part of individuation itself, inasmuch as it has place, by reason of which, in abstracting from sensible matter, we may imagine this line and this circle. Hence it rightly pertains to matter to individuate all other forms, because it gives to this form, which of itself has the nature of individuation, that it also be terminated by those dimensions that are found in a subject now made complete; accordingly they are individuated by matter which is individuated by indeterminate dimensions conceived of as in matter.

4. It may be said: Things that differ numerically in the genus of substance, differ not dinly because of accidents, but also by reason of form and matter; but if it is asked how this form differs from that, the only reason can be that it is in other signate matter. Nor can there be found another reason why this matter is divided from that except by reason of its quantity. Hence matter subject to dimension is undersiood to be the principle of this kind of diversity.

5. It may be said: This reasoning relates to completed accidents which follow upon the existence of a form in matter; but not to those indeterminate dimensions which may be conceived of before the reception of the form in matter. For without these, a thing cannot be understood to be ‘ individual, any more than it can be conceived of without form.

6. It may be answered: Number, formally speaking, is prior to continuous quantity: but materially, continuous quantity is prior, since number is the result of the division of a continuum, as is said in IV Physic. In this way, division of matter, according to dimensions, causes numerical diversity.

As to contrary reasons proposed, it is clear what must be conceded and what false conclusions have been deduced.

Article 3

Whether Two Bodies Can Be, or Can Be Conceived of as Being Simultaneously in the Same Place


1. It seems that two bodies can be conceived of as being in the same place. For any proposition seems to be intelligible in which there is included no opposition of the predicate to the subject, since such a proposition contains nothing repugnant to understanding. But this proposition, “Two bodies are in the same place,” is not a proposition repugnant to the intellect. Otherwise it could not happen miraculously, a thing evidently false regarding the body of our Lord, which came forth from the closed womb of the Virgin, and which entered into the midst of the disciples, the doors being shut. Now, even God cannot cause affirmation and negation to be simultaneously true, as Augustine says in answer to Faustus; therefore one can understand, or at least conceive of in his mind, that two bodies could be in the same place at the same time.

2. From glorified bodies there will be removed not the nature of corporeity, but only that of corpulentia (bodily mass). When this is removed, the possibility of being with other bodies in the same place is theirs by reason of the gift of subtlety, as is said by many. Therefore this condition does not follow the nature of corporeity, but that of corpulentia, of a certain mass. Therefore it is not impossible to conceive of two bodies being simultaneously in the same place.

3. Augustine, in commenting upon the Book of Genesis speaks,of light as holding first place among corporeal things; but light is simultaneously in the same place with air; therefore two bodies can be in the same place at the same time. Any species of fire, as the Philosopher says in V Topic., is a body; and so the conclusion is like the previous one.

5. In glowing iron, the fire and the iron are simultaneous; but each is a body; therefore it is possible for two bodies to be in the same place at the same time.

6. Elements in a compound are not corrupted; otherwise a compound would not follow the motion of a dominant element; but all four elements are bodies and are simultaneously in every part of the compound; therefore it is possible for two bodies to be simultaneously in the same place.

7. The fact that two bodies are not simultaneously in one place does not occur by reason of the matter of the bodies, since to matter in itself there is no due place; nor does it occur because of the form, for the same reason; nor is it because of dimension, since dimensions do not fill up place, as is evident from the fact that certain philosophers are accustomed to say that the place where there are only dimensions is a vacuum. Therefore this characteristic of a body must arise only from certain posterior accidents, which are not altogether common and which can be separated from the body; and so it seems that two bodies could be simultaneously in the same place.

8. According to the astrologers who follow Ptolemy, the six bod?es of the planets move in epicycles, which are circles intersecting the spheres extrinsic to the planets. Therefore it must be that a body of a planet at some time would arrive at the place of section. But it cannot be said that at that place there is any vacuum, since nature does not suffer this; nor that the substance of the spheres is divisible, so that it might be thought of as giving way when the planetary body had reached it, as air gives way to a stone, for the heavens are most solid, being formed, as it were, of molten brass, as is said in Job, 37:18. Therefore it must be that the body of the planet is simultaneously in the same place as the body of the sphere; and so Boethius falsely says that two bodies cannot occupy one and the same place.

Sed contra

On the contrary is the fact that if two bodies are in one and the same place, they are the same in nature and in every respect; but any body, however large, can be divided into small bodies of any qqantity, according to any number; therefore, it would follow that in the very smallest place there would be contained the largest body, a thing which appears to be absurd.

Again, it is impossible for there to be many straight lines between two given points. But this would follow if two bodies could be in the same place. For then, given two points in two opposite parts of space, there will be between them two straight lines assigned corporeally to two places. Now, it cannot be said that between these two points there will be no lines at all, or that a line of one location would be greater than the other, or that there could be any one line apart from those corporeally located between the two points of given location, for in that case the two lines would not be in a subject. Therefore it is impossible for two bodies to be simultaneously in the same place.

Again, it has been demonstrated in geometry that two circles are tangent only at one point: but if we posit two bodies being simultaneously in the same place, it would follow that two circles could be totally tangent. Therefore it is impossible that two bodies should be in the same place at the same time.

Again, whatever things are equal to one and the same thing are equal to each other; but since local dimension must be one with a localized body (since no dimension can be supposed without a subject), if two bodies could be simultaneously in the same place, it would follow that the dimensions of each body would be equal to the dimensions of the place; therefore it would follow that the bodies would be the same, but this is impossible.

Response. I answer that it must be said that in those things belonging to our world, all of which are judged to be corporeal, we see from sense experience that when one body arrives at any given place, any other body is expelled from that place; therefore it is experimentally evident that two such bodies cannot be in the same place.

There are, however, certain philosophers who declare that two bodies are not thus prohibited from simultaneous occupation of the same place on account of their corporeity, or on account of anything else which belongs to the nature of a body, as a body, for thus it would follow that it would be altogether impossible for two bodies to exist simultaneously [in the same place]. But they say that this prohibition is due only to their corpulentia. But whatever this corpulentia may mean—whether density or impurity or corruptibility which attends certain bodies, or even some special nature superadded to the general nature of corporeity—the prohibition can be on account of none of these things.

Now, there is to be found a double relation of a body to place. One is according as it has location in this or that determined place; and this relationship follows upon the specific nature of this or that body, just as heavy things, by the very nature of their gravity, hold a lower place, but light bodies, a higher place.

But another relationship prevails according as a body is said, absolutely, to be in place: and this relationship characterizes a bodily thing by the very nature of its corporeity, not because of anything additional. For according as a particular body is in place, it is commensurate with that place; but this is because it has dimensions that are equal and similar to the dimensions of the place; moreover, dimensions belong to every body by reason of its very corporeity. For, that many bodies should or should not be in the same place, has no relation to a determined place, but regards place absolutely; therefore it must be that the cause of this impediment should be referred to the nature of corporeity, by reason of which every body, inasmuch as it is a body, is destined to be in place.

And if the last sphere should not be in place, this is so only because nothing can be outside it, but not because it is lacking in the aforesaid aptitude to occupy place.

Hence there are others who concede that, absolutely, no two bodies can be in the same place at the same time, and they assign the reason for this to mathematical principles, which ought to be observed in all the natural sciences, as is said in III Coel. et mun. But this reason does not seem fitting, because it does not pertain to the objects of mathematics to be in place, except improperly and by similitude, as is said in II De generatione. Hence, the reason for maintaining this impediment should not be derived from mathematical principles, but from the principles of natural things, to which place is properly due. Furthermore, mathematical reasoning is sufficiently conclusive only in regard to its own matter. For, although mathematical truths are preserved in natural sciences, beings of the natural order add something over and above what is possessed by, mathematical beings: namely, sensible matter; and because of this addition it is possible to assign as an explanation of something in the natural order what would not be assigned in explanation of an object of mathematics. For in mathematics no reason for diversity of two given lines can be assigned except because of their situation; wherefore, if diversity of situation is removed, there remains no plurality of mathematical lines, and likewise no diversity of surfaces or of bodies. On this account mathematical bodies cannot be both many and simultaneous, and in like manner neither can lines or surfaces.

But in regard to corporeal things in nature, it is possible to assign another and different reason for diversity: namely, that of sensible matter, even though diversity of situation were removed. Hence the reasoning which proves that two mathematical bodies cannot be simultaneously in the same place does not suffice for proving that two bodies in the natural order could not be simultaneous. And therefore the explanation of Avicenna must be accepted, which he uses in his Sufficientia, in the treatise De loco. In this explanation he assigns as reason of the aforesaid prohibition one which, by natural principles, is owing to the very nature of corporeity itself. For he says there can be no cause of this prohibition except that it pertains, first and per se, to a thing to be in place: but this means that it is destined by its nature to fill a place. Moreover, it does not pertain to a form to be in place, except accidentally; although certain forms are the principles by which a body is inclined to this or that place. Likewise neither does it pertain to matter, considered per se, to be in place, because, as so considered, it is understood apart from all genera, as is said in VII Metaph. Wherefore it must be that matter, according as it is subject to that by which it has primary relation to place, is the cause of this prohibition; but it is related to place inasmuch as it is subject to dimensions: hence it is by nature of matter subject to dimensions that many bodies are prohibited from being in the same place.

For, wherever the form of corporeity is found to be divided, there must be a plurality of bodies; but this division does not take place except by division of matter. Since division of matter is only by dimensions, because of which matter has situation, it is impossible that this matter should be distinct from that unless it is distinct according to situation. But this would not be the case if two bodies were posited as being in the same place; for then they would not be two bodies but one body, a thing which is impossible. Since, therefore, matter subject to dimensions is found in all corporeal things, it must be by reason of the very nature of corporeity that any two bodies are prohibited from being in the same place at the same time.

Answers to objections

1. It may be said: A proposition may be called not-intelligible in two ways. In one way, it may be on the part of the one understanding, because of the deficiency of his intellect, as is the case in relation to this proposition: “In the three divine Persons there is one essence.” In a proposition of this kind, there can be, indeed, no contradiction.

In another way, non-intelligibility may be on the part of the proposition, and this again for two reasons. In one way because it implies a contradiction, absolutely, as for example, “The rational is irrational”; and not even by a miracle can propositions of this sort be made true. In another way, because they imply a contradiction in a certain manner, as this proposition: “The dead man rose to life by his own (proper) power”; for, by the fact that he is said to be “dead,” it is posited that he is destitute of every principle of life. Propositions of this kind can be made true by the miraculous operation of a superior power; and such is the case in regard to this proposition. For just as there can be found no natural cause of diversity for two bodies in the same place, so, by divine power, it is possible that two bodies be in the same place and that, although united in situation, their, distinction be conserved, as does miraculously happen.

2. It may be said: Whatever may be this corpulentia, which is said to be removed from glorified bodies, nevertheless it is evident that corporeity will not be removed from them; therefore, neither will the cause which naturally prohibits any one of them from simultaneously occupying the same place with another; but only by a miracle is it possible that a glorified body be in the same place simultaneously with other bodies.

3. It may be answered: Light is not a body, but a certain quality, as Damascene says, and Avicenna also. But Augustine gives light the same name as fire, as is evident from the fact that he speaks of light as contradistinguished from air, water, and earth.

4. It may be answered: The three species of fire spoken of by the Philosopher are to be understood in such a way that by “light” is understood fire existing in its proper matter, and granted also, as some say, that fire in its own proper sphere emits no light. For it does not belong to the nature of light to be luminous, but by participation in it other things become so. The same is true of fire: for, although in its own sphere it emits no light, nevertheless, by participation in it, other things become refulgent. By flame, however, is to be understood fire in the air; and by carbo, fire in terrestrial matter. In aqueous matter, however, fire cannot continue in such a way as to have the nature of fire, because water has qualities which are altogether opposed to fire.

5. It must be said: In iron which has become ignited there are not two bodies, but one body having indeed the species of iron, but certain properties of fire.

6. It may be answered: Although elements in a compound are supposed to remain according to their substantial forms, nevertheless it is not supposed that there are then many bodies in act, for otherwise no compound would be truly one; but while it is potentially many, it is one in act.

Nevertheless the opinion of the Commentator, III Coel. et mun., seems the more probable. In rejecting the opinion of Avicenna, he says that the forms of elements neither remain in a compound nor are altogether corrupted, but that from them there comes to be one common or neuter form inasmuch as they comprise it, more or less. But since to give rise to a substantial form “more or less” seems an improbability, it appears that this saying ought to be understood in this way: that the forms of the elements are receptive of more or less (or comprise the form of the compound, more or less), not secundum se, but according as they remain in elementary qualities, as it were in their proper instruments. And thus it is said: Forms remain virtually in the qualities of the elements certain instrumental properties, as it were. Forms secundum se, do not remain, but only according as they remain virtually in their qualities, out of which there is made one, median, or common quality.

7. It may be said: Although dimensions of themselves cannot fill out a place, nevertheless a natural body, because of the fact that its matter is understood to be subject to dimensions, has the natural characteristic of filling a place.

8. It may be said: The opinion of Ptolemy regarding epicycles and eccentrics does not seem consonant with principles of natural philosophy which Aristotle holds; hence this opinion is not acceptable to the followers of Aristotle. If, however, it should be sustained, no necessity arises for supposing two bodies to be in the same place since, according to those who hold this opinion, the substances of heavenly bodies are distinguished as of three kinds: namely, the substance of the stars, which is luminous; the substance of the spheres, which is diaphanous and solid, but not divisible; and another kind of substance, which is between the spheres, and which is divisible and of resisting density, after the manner of the air, although this substance is incorruptible. And thus those who hold the theory of this third substance have no need to say that the substance of the spheres is divided or that two bodies occupy the same place simultaneously.

Article 4

Whether Variety of Location Has Any Influence in Effecting Numerical Difference


1. It seems that variety of location effects nothing as regards diversity according to number. For the cause of diversity acicording to number is in those things which differ numerically; but place is outside things that are located; therefore diversity of place cannot be the cause of numerical diversity.

2. A thing is not complete in being unless it is distinct from others; but place comes after complete being; therefore motion to a place is the motion of that which is perfect according to substance, as is said in IX Physic. Therefore it is not possible that any cause of the distinction of bodies occupying space should be derived from place.

3. Numerical distinction is invariable as regards things that are distinct: but an invariable effect cannot proceed from a variable cause; therefore, since place varies in regard to that having location, it is not possible for diversity according to place to be the cause of numerical diversity.

4. If a cause is removed, so also is its effect: but it sometimes happens by a miracle that distinction of place is removed in respect to two bodies, as has been previously said; yet distinction according to number is not removed; therefore distinction according to place is not the cause of numerical diversity.

5. Diversity according to number is found not only in corporeal things, but even in incorporeal substances; but in these latter, diversity according to place cannot be the cause of numerical diversity, since incorporeal beings are not in a place, as Boethius himself says in his book, De hebdomadibus; therefore diversity according to place cannot be taken as the cause of diversity according to number, that is, as its cause by very reason of its nature, as he himself seems to say.

Sed contra

On the contrary is the fact that things differing according to number differ by reason of their accidents: but the diversity of no other accident is so inseparablv related to diversity in number as is diversity of location; therefore diversity in place seems especially to influence diversity in number.

Again, diversity of location according to the species of things is concomitant with the diversity of bodies according to their species, as is evident in the case of heavy and light bodies. Therefore also diversity of places according to number is indivisibly concomitant with diversity of bodies according to number, and so the conclusion is the same as before.

Again, as time is the measure of motion, so place is the measure of a body: but motion is divided numerically according to time, as is said in V Physic.; therefore also what is corporeal is divided numerically according to place.

Response. I answer: It must be said that, as is evident from previous statements, diversity according to number is caused by division of matter existing under dimensions. Now, matter itself, according as it exists under dimensions, prohibits two bodies from being in the same place, inasmuch as in each of the two bodies there must be matter distinct in its situation. And thus it is evident that diversity according to number is caused by the same thing as diversity of location in diverse bodies. Hence diversity of location, considered in itself, is a sign of the diversity which exists according to number—just as is also true of other accidents, except the first indeterminate dimensions which have been previously discussed. But if diversity of place is considered according to its own cause, then it is clear that diversity of place is the cause of diversity according to number. Therefore Boethius says it is variety of accidents that produces diversity according to number. But if all other accidents are removed, numerical diversity still remains verifiable by reason of the diversity of things in place; since, indeed, no other of those accidents which appear as extrinsic to a complete being is so closely related to the cause of diversity according to number as is diversity of location.

Answers to objections. 1-3. To the first, second, and third objections it may be said: These reasons show conclusively that diversity of place is not the cause of diversity of individuals, secundum se., but this does not refute the fact that the cause of diversity of locations is the cause of diversity according to number.

4. It may be answered: All effects of second causes depend more on God than on secondary causes, since either with these second causes, or without them, He is able to produce miraculously whatever effects He wills.

5. It may be said: In corporeal substances diversity according to species follows diversity according to number, except in the case of the rational soul, which follows division of matter disposed for it. Here, however, Boethius is speaking of diversity according to number where the species is the same.

Further answers

1. In contradiction to the first objection, it may be said: Variety of accidents, because of indeterminate dimensions, does not produce diversity in number after the manner of a cause, but this variety is said to produce, a sign indicating numerical diversity; and diversity of place does this in a special way, inasmuch as it is the sign, most closely related to numerical diversity.

2. To the second, it may be answered: Diversity of locations according to species is a sign of diversity of bodies according to their species, but not a cause of specific diversity.

3. To the third, it may be said: Although division of time is caused by division of motion, diversity, even diversity of time is not the cause of diversity of motion, but a sign of it; and the same is true of location in its relation to a body.


Boethius’ Text

1.1 Let us now begin a careful consideration of each several point, as far as it can be grasped and understood; for it has been wisely said, in my opinion, that it is a scholar’s duty to formulate his belief about anything according to its real nature.

1.2. Speculative science may be divided into three kinds: physics, mathematics, and theology. Physics deals with motion and is not abstract or separable; for it is concerned with forms of bodies together with their constituent matter, which forms cannot be separated in reality from their bodies. As bodies are in motion—the earth, for instance, tending downward, and fire tending upward—form takes on the movementof the particular thing to which it is annexed. Mathematics does not deal with motion and is not abstract, for it investigates forms of bodies apart from matter, and therefore apart from movement, which forms being connected with matter cannot really be separated from bodies. Theology does not deal with motion and is abstract and of things inseparable, for the divine substance is without matter or motion. In physics we are bound to use scientific concepts, in mathematics systematic concepts, in theology intellectual concepts; and in theology we will not let ourselves be diverted to play with imaginations, but will consider simply form.

2. Which form, indeed...

St. Thomas’ Commentary

1.1 Boethius has previously set forth the doctrine of the Catholic faith regarding the unity of the Trinity, and indicated the reason of this belief. Now he intends to proceed to an investigation of the aforesaid doctrine. Since, according to the opinion of the Philosopher in II Metaph., inquiry into the method of a science ought to precede science itself, he therdore divides this section into two parts. In the first place Boethius points out the method proper for this kind of inquiry, which is concerned with divine things. In the second place he proceeds, according to the method he has indicated, to inquire into the proposition determined upon, where he says, “Which form, indeed.”

The first part is again divided into two sections: first. he indicates the necessity of making clear the method of investigation. Secondly, he shows that the method of the present inquiry is suitable, saying: “Speculative science may be divided into three kinds.” Therefore he says: “Wherefore it is certain that this is the doctrine of the Catholic faith regarding the unity of the Trinity, and the nature of that unity without difference.”

Thereupon, he says by way of exhortation, “Let us now begin,” that is, let us inquire more deeply, carrying our investigation to an examination of the intimate principle of things and of truth which is, as it were, veiled and hidden away from view. And that method which he deems fitting is indicated by the words: “Let us now begin a careful consideration of each several point, as far as it can be grasped and understood,” that is, according to the mode by which. understanding and apprehension are possible. Moreover, he uses the two words (“grasped” and “understood”) because the method of any investigation ought to be in harmony both with things and with us. For if it is not suited to the matter, things will not be understood; and if it is not suited to us, we shall not be able to apprehend the matter; for example, divine things are such by their very nature that they cannot be known except by intellect. Wherefore, if anyone wished to follow another way and to use imagination instead, he would not be able to understand anything of them as a result of his consideration, because truths, of this kind are not thus to be known. But if, on the other hand, one wished to know divine things so as to see them in themselves, and to comprehend them with the same certitude with which sensible things or mathematical demonstrations are comprehended, this too would be impossible; even things which are, in themselves, understandable in this way cannot be perfectly grasped because of the weakness of our intellect.

He also shows that the mode of inquiry used must always correspond to the kind of investigation undertaken, by reference to the authority of the Philosopher in I Ethic. when he says: “For it has been wisely said that it is a scholar’s duty to formulate his belief about anything according to its real nature.” So, in regard to a doctrine of faith, the same principle must be applied: for in all cases, equal certitude and demonstrative evidence cannot be demanded. And these are the very words of the Philosopher in I Ethic.: “It is the duty of the scholar to demand as much certitude in his investigation of each thing as the nature of that thing permits.”

1.2 In the second place, when he says: “Speculative science may be divided into three kinds,” he inquires into the method of his own investigation, testing its congruousness by distinguishing it from the methods employed in other sciences; and, since method ought to correspond to the matter under investigation, he therefore divides this part of his consideration into two sections.

First, he distinguishes sciences according to the matter with which each is concerned. Secondly, he indicates the methods suitable for each kind of matter, beginning, “Physics deals.”

In regard to the first point, he does three things. First, he shows what the objects of natural philosophy are. Secondly, he indicates the objects of mathematics. Thirdly, he speaks of the truths with which divine science is concerned, when he says: “Theology does not.” Therefore he says: “It has been wisely said that it is a scholar’s duty to formulate his belief about anything according to its real nature.” For, since there are three divisions of speculative science (or philosophy), and he calls it “speculative” to differentiate it from ethics, which is operative or practical; in each of these the method must be in conformity with the matter. The three divisions of speculative science indicated are physics or natural science, mathematics, and divine science or theology. While, I say, there are three divisions, natural philosophy, which is one of the, three, “deals with motion and,is not abstract,” that is, it is concerned with things in motion and not abstracted from matter. This he proves by examples, as is evident in his treatise. When, however, he says: “Form takes on the movement of the particular thing to which it is annexed,” his words should be understood as follows: that what is composite of matter and form, inasmuch as it is due the nature of a thing of this kind, has motion; or, in other words, a form existing in matter is the principle of motion. Therefore the consideration of things that are material and of things that are in motion is the same. He then indicates the subject matter of mathematics, saying: “Mathematics does not deal with motion”; that is, it involves no consideration of motion or of movable things, and on this point it differs from natural philosophy. Mathematics, moreover, is said to be “not abstract”; that is, it considers forms which according to their existence are not abstract from matter, and in this respect it is in agreement with natural philosophy. He then explains. how this is: Mathematics considers forms which are without matter and hence without motion, because wherever there is matter there is motion, as is proved in X Metaph. For according as things have matter there will also be motion, and thus the speculations of a mathematician are without matter and without motion, although these forms, namely, those about which the mathematician speculates, “being connected with matter, cannot really be separated from bodies,” according to their being [real existence]; but according to speculation, they can be considered as separable. Then he indicates the objects of divine science, calling it, ‘theology,” that is, the third division of speculative science, which is termed divine, or metaphysics, or first philosophy; and it deals with objects apart from motion, in which it agrees with mathematics and differs from natural philosophy. It also is “abstract,” namely, from matter, and “inseparable”; and because of these two facts it differs from mathematics. For the objects of divine science are of themselves abstract from matter and motion, but those of mathematics are not thus naturally abstract, but separable in thought. The objects of divine science, however, are called “inseparable” because a thing is not separable unless there is some conjunction with matter. Hence the objects of divine science are not separable from matter by thought, but are abstract according to their very being; while the converse is true in the case of the objects of mathematics. This he proves by the fact that the substance with which divine science is principally concerned is that of God, and on this account it is called “divine.” In the next place, when he says, “In physics, then, we are bound to use scientific concepts, in mathematics systematic concepts, in theology intellectual concepts.” He points out the methods that correspond to the aforesaid divisions. Here he treats of two things. First, he draws conclusions about the methods appropriate for each of the divisions named, and the disposition of this section is left open for discussion. Secondly, he describes the last mode, which is that proper to the present investigation, and indicates a twofold procedure: first, by the removal of that which is an impediment to speculation saying, ‘In theology we will not let ourselves be diverted to play with imaginations (that is, in such a way that in formulating judgments we follow the judgment of the imagination) but will consider simply form.” Secondly, he indicates the method which is the proper one when he says: “but will consider simply form” (apart from motion and matter), the nature of which he consequently explains in beginning his treatment of the proposed question.


The Division of Speculative Science

There are two questions here. The first concerns the division of speculative science which the text proposes, the second concerns the methods it attributes to the parts of speculative science. With regard to the first question there are four points of inquiry:

1. Is speculative science appropriately divided into these three parts: natural, mathematical, and divine?

2. Does natural philosophy treat of what exists in motion and matter?

3. Does mathematics treat, without motion and matter, of what exists in matter?

4. Does divine science treat of what exists without matter and motion?


Is Speculative Science Appropriately Divided into these Three Parts:

Natural, Mathematical, and Divine?

We proceed as follows to the first article:

It seems that speculative science is not appropriately divided into these three parts, for:

1. The parts of speculative science are the habits that perfect the contemplative part of the soul. But the Philosopher says in the Ethics that the scientific part of the soul, which is its contemplative part, is perfected by three habits, namely, wisdom, science, and understanding. Therefore these are the three divisions of speculative science, not those proposed in the text.

2. Again, Augustine says that rational philosophy, or logic, is included under contemplative or speculative philosophy. Consequently, since no mention is made of it, it seems the division is inadequate.

3. Again, philosophy is commonly divided into seven liberal arts, which include neither natural nor divine science, but only rational and mathematical science. Hence natural and divine should not be called parts of speculative science.

4. Again, medicine seems to be the most practical science, and yet it is said to contain a speculative part and a practical part. By the same token, therefore, all the other practical sciences have a speculative part. Consequently, even though it is a practical science, ethics or moral science should be mentioned in this division because of its speculative part.

5. Again, the science of medicine is a branch of physics, and similarly certain other arts called “mechanical,” like the science of agriculture, alchemy, and others of the same sort. Therefore, since these sciences are practical, it seems that natural science should not be included without qualification under speculative science.

6. Again, a whole should not be contra-distinguished from its part. But divine science seems to be a whole in relation to physics mathematics, since their subjects are parts of its subject of divine science or first philosophy is being; and changeable substance, which the natural scientist considers, and also quantity, which the mathematician considers, are parts of being. This is clear in the Metaphysics. Therefore, divine science should not be contra-distinguished from natural science and mathematics.

7. Again, as it is said in the De Anima, sciences are divided in the same manner as things. But philosophy concerns being, for it is knowledge of being, as Dionysius says. Now being is primarily divided into potency and act, one and many, substance and accident. So it seems that the parts of philosophy ought to be distinguished by such divisions of being.

8. Again, there are many other divisions of beings studied by sciences more essential than the divisions into mobile and immobile and into abstract and non-abstract; for example, the divisions into corporeal and incorporeal and into living and non-living, and the like. Therefore differences of this sort should be the basis for the division of the parts of philosophy rather than those mentioned here.

9. Again, that science on which others depend must be prior to them. Now all the other sciences depend on divine science because it is its business to prove their principles. Therefore Boethius should have placed divine science before the others.

10. Again, mathematics should be studied before natural science, for the young can easily learn mathematics, but only the more advanced natural science, as is said in the Ethics. This is why the ancients are said to have observed the following order in learning the sciences: first logic, then mathematics, then natural science, after that moral science, and finally men studied divine science. Therefore, Boethius should have placed mathematics before natural science. And so it seems that this division is unsuitable.

On the contrary, the Philosopher proves the appropriateness of this division in the Metaphysics, where he says, “There will be three philosophical and theoretical sciences, mathematics, physics, and theology. Moreover, in the Physics three methods of the sciences are proposed which indeed seem to belong to these three. Moreover, Ptolemy also uses this division in the beginning of his Almagest.

Reply: The theoretical or speculative intellect is properly distinguished from the operative or practical intellect by the fact that the speculative intellect has for its end the truth that it contemplates, while the practical intellect directs the truth under consideration to activity as to an end. So the Philosopher says in the De Anima that they differ from each other by their ends; and in the Metaphysics he states that “the end of speculative knowledge is truth, but the end of practical knowledge is action.” Now, since matter must be proportionate to the end, the subject-matter of the practical sciences must be things that can be made or done by us, so that we can direct the knowledge of them to activity as to an end.

On the other hand, the subject-matter of the speculative sciences must be things that cannot be made or done by us, so that our knowledge of them cannot be directed to activity as to an end. And the speculative sciences must differ according to the distinctions among these things. Now we must realize that when habits or powers are differentiated by their objects they do not differ according to just any distinction among these objects, but according to the distinctions that are essential to the objects as objects. For example, it is incidental to a sense object as such whether it be an animal or a plant. Accordingly, the distinction between the senses is not based upon this difference but rather upon the difference between color and sound. So the speculative sciences must be divided according to differences between objects of speculation, considered precisely as such. Now an object of this kind ─ namely, an object of a speculative power ─ derives one characteristic from the side of the power of intellect and another from the side of the habit of science that perfects the intellect. From the side of the intellect it has the fact that it is immaterial, because the intellect itself is immaterial. From the side of habit of science it has the fact that it is necessary, for science treats of necessary matters, as is shown in the Posterior Analytics. Now everything that is necessary is, as such, immobile, because everything changeable is, as such, able to be or not to be, either absolutely or in a certain respect, as is said in the Metaphysics. Consequently, separation from matter and motion, or connection with them, essentially belongs to an object of speculation, which is the object of speculative science. As a result, the speculative sciences are differentiated according to their degree of separation from matter and motion.

(1) Now there are some objects of speculation that depend on matter for their being, for they can exist only in matter. And these are subdivided. (a) Some depend on matter both for their being (+) and for their being understood, as do those things whose definition contains sensible matter and which, as a consequence, cannot be understood without sensible matter. For example, it is necessary to include flesh and bones in the definition of man. It is things of this sort that physics or natural science studies. (b) On the other hand, there are some things that, although dependent upon matter for their being, do not depend upon it (~) for their being understood, because sensible matter is not included in their definitions. This is the case with lines and numbers ─ the kind of objects with which mathematics deals. (2) There are still other objects of speculative knowledge that do not depend upon matter(~) for their being, because they can exist without matter; (a) either they never exist in matter, as in the case of God and the angels, or (b) they exist in matter in some instances and not in others, as in the case of substance, quality, being, potency, act, one and many, and the like. The science that treats of all these is theology or divine science, which is so called because its principal object is God. By another name it is called metaphysics; that is to say, “beyond physics”, because it ought to be learned by us after physics; for we have to proceed from sensible things to those that are non-sensible. It is also called first philosophy, inasmuch as all the other sciences, receiving their principles from it, come after it. Now there can be nothing that depends upon matter for its being understood but not for its being, because by it; very nature the intellect is immaterial. So there is no fourth kind of philosophy besides the ones mentioned.

Reply to the Opposing Arguments:

Reply to 1. ln the Ethics the Philosopher considers the intellectual habits insofar as they are intellectual virtues. Now they are called virtues because they perfect the intellect in its operation; for “virtue makes its possessor good and renders his work good.” So he distinguishes between virtues of this sort in as much as speculative habits perfect the intellect in different ways. In one way the speculative part of the soul is perfected by understanding, which is the habit of principles, through which some things become known of themselves. In another way it is perfected by a habit through which conclusions demonstrated from these principles are known, whether the demonstration proceeds from inferior causes, as in science, or from the highest causes, as in wisdom. But when sciences are differentiated insofar as they are habits, they must be distinguished according to their objects, that is, according to the things of which the sciences treat. And it is in this way that both here and in the Metaphysics speculative philosophy is distinguished into three parts.

Reply to 2. As is evident in the beginning of the Metaphysics, the speculative sciences concern things the knowledge of which is sought for their own sake. However, we do not seek to know the things studied by logic for themselves, but as a help to the other sciences. So logic is not included under speculative philosophy as a principal part but as something brought under speculative philosophy as furnishing speculative thought with its instruments, namely, syllogisms, definitions, and the like, which we need in the speculative sciences. Thus, according to Boethius, logic is not so much a science as the instrument of science.

Reply to 3. The seven liberal arts do not adequately divide theoretical philosophy; but, as Hugh of St. Victor says, seven arts are grouped together (leaving out certain other ones), because those who wanted to learn philosophy were first instructed in them. And the reason why they are divided into the trivium and quadrivium is that “they are as it were paths (viae) introducing the quick mind to the secrets of philosophy.” This is also in harmony with the Philosopher’s statement in the Metaphysics that we must investigate the method of scientific thinking before the sciences themselves. And the Commentator says in the same place that before all the other sciences a person should learn logic, which teaches the method of all the sciences; and the trivium concerns logic. The Philosopher also says in the Ethics that the young can know mathematics but not physics, because it requires experience. So we are given to understand that after logic we should learn mathematics, which the quadrivium concerns. These, then, are like paths leading the mind to the other philosophical disciplines. We may add that among the other sciences these are called arts because they involve not only knowledge but also a work that is directly a product of reason itself; for example, producing a composition, syllogism or discourse, numbering, measuring, composing melodies, and reckoning the course of the stars. Other sciences (such as divine and natural science) either do not involve a work produced but only knowledge, and so we cannot call them arts, because, as the Metaphysics says, art is “productive reason”; or they involve some bodily activity, as in the case of medicine, alchemy, and other sciences of this kind. These latter, then, cannot be called liberal arts because such activity belongs to man on the side of his nature in which he is not free, namely, on the side of his body. And although moral science is directed to action, still that action is not the act of the science but rather of virtue, as is clear in the Ethics. So we cannot call moral science an art; but rather in these actions virtue takes the place of art. Thus, as Augustine says, the ancients defined virtue as the art of noble and well-ordered living.

Reply to 4. As Avicenna says, the distinction between theoretical and practical is not the same when philosophy is divided into theoretical and practical, when the arts are divided into theoretical and practical, and when medicine is so divided. For when we distinguish philosophy or the arts into theoretical and practical we must do so on the basis of their end, calling that theoretical which is directed solely to knowledge of the truth, and that practical which is directed to operation. However, there is this difference when we distinguish the whole of philosophy and the arts on this basis. We divide philosophy with respect to the final end or happiness, to which the whole of human life is directed. For, as Augustine says, following Varro, “There is no other reason for a man philosophizing except to be happy.” And since the philosophers teach that there is a twofold happiness, one contemplative and the other active, as is clear in the Ethics, they have accordingly a]so distinguished between two parts of philosophy, calling moral philosophy practical and natural and rational philosophy theoretical. But when they call some arts speculative and some practical, this is on the basis of some special ends of those arts; as when we say that agriculture is a Practical art but dialectic is theoretical. However, when we divide medicine into theoretical and practical, the division is not on the basis of the end. For on that basis the whole of medicine is practical, since it is directed to practice. But the above division is made on the basis of whether what is studied in medicine is proximate to, or remote from practice. Thus we call that part of medicine practical which teaches the method of healing; for instance, that these particular medicines should be given for these abscesses. On the other hand, we call that part theoretical which teaches the principles directing a man in his practice, although not immediately; for instance, that there are three virtues, and that there are so many kinds of fever. Consequently, if we call some part of a practical science theoretical, we should not on that account place that part under speculative philosophy.

Reply to 5. One science is contained under another in two ways: in one way, as its part, because its subject is part of the subject of that other science, as plant is part of natural body. So the science of plants is also contained under natural science as one of its parts. In another way, one science is contained under another as subalternated to it. This occurs when in a higher science there is given the reason for what a lower science knows only as a fact. This is how music is contained under arithmetic. Medicine, therefore, is not contained under physics as a part, for the subject of medicine is not part of the subject of natural science from the point of view from which it is the subject of medicine. For although the curable body is a natural body, it is not the subject of medicine insofar as it is curable by nature, but insofar as it is curable by art. But because art is nature’s handmaid in healing (in which art too plays a part, for health is brought about through the power of nature with the assistance of art), it follows that the reason for the practices used in the art must be based on the properties of natural things. So medicine is subalternated to physics, and for the same reason so too are alchemy, the science of agriculture, and all sciences of this sort. We conclude, then, that physics in itself and in all its parts is speculative, although some practical sciences are subalternated to it.

Reply to 6. Although the subjects of the other sciences are parts of being, which is the subject of metaphysics, the other sciences are not necessarily parts of metaphysics. For each science treats of one part of being in a special way distinct from that in which metaphysics treats of being. So its subject is not properly speaking a part of the subject of metaphysics, for it is not a part of being from the point of view from which being is the subject of metaphysics; from this viewpoint it is a special science distinct from the others. However, the science treating of potency, or that treating of act or unity or anything of this sort, could be called a part of metaphysics because these are considered in the same manner as being, which is the subject of metaphysics.

Reply to 7. These parts of being require the same manner of consideration as being-in-general (ens commune) because they too are independent of matter. For this reason the science dealing with them is not distinct from the science of being-in-general.

Reply to 8. The other diversities of things mentioned in the objection do not differentiate those things essentially as objects of knowledge. So the sciences are not distinguished according to them.

Reply to 9. Although divine science is by nature the first of all the sciences, with respect to us the other sciences come before it. For as Avicenna says, the position Or this science is that it be learned after the natural sciences, which explain many things used by metaphysics, such as generation, corruption, motion, and the like. It should also be learned after mathematics, because to know the separate substances metaphysics has to know the number and disposition of the heavenly spheres, and this is impossible without astronomy, which presupposes the whole of mathematics. Other sciences, such as music, ethics, and the like, contribute to its fullness of perfection. Nor is there necessarily a vicious circle because metaphysics presupposes conclusions proved in the other sciences while it itself proves their principles. For the principles that another science (such as natural philosophy) takes from first philosophy do not prove the points which the first philosopher takes from the natural philosopher, but they are proved through other self-evident principles. Similarly the first philosopher does not prove the principles he gives the natural philosopher by principles he receives from him, but by other self-evident principles. So there is no vicious circle in their definitions. Moreover, the sensible effects on which the demonstrations of natural science are based are more evident to us in the beginning. But when we come to know the first causes through them, these causes will reveal to us the reason for the effects, from which they were proved by a demonstration quia. In this way natural science also contributes something to divine science, and nevertheless it is divine science that explains its principles. That is why Boethius places divine science last, because it is the last relative to us.

Reply to 10. Although we should learn natural science after mathematics because the general proofs of natural science require experience and time, still, since natural things fall under the senses, they are by nature better known than the mathematical entities abstracted from sensible matter.


Does Natural Philosophy Treat of What Exists in Motion and Matter?

We proceed as follows to the second article:

It seems that natural science does not treat of things that exist in motion and matter, for

1. Matter is the principle of individuation, Now, according to Plato’s doctrine, which is followed by Porphyry, no science treats of individual things but only of universals. Therefore, natural science does not treat of what is in matter.

2. Again, science pertains to the intellect. But the intellect knows by abstracting from matter and from the conditions of matter. Therefore, no science can treat of what is not abstracted from matter.

3. Again, as is clear in the Physics, the First Mover is considered in natural science. But The First Mover is free from all matter. Therefore, natural science does not treat only of what is in matter.

4. Again, every science has to do with what is necessary. But whatever is moved, as such is contingent, as is proved in the Metaphysics. Therefore, no science can treat of what is subject to motion; and so neither can natural science.

5. Again, no universal is subject to motion; for as is said in the beginning of the Metaphysics, it is not man in general who is healed, but this man. But every science concerns that which is universal. Therefore natural science does not treat of what is in motion.

6. Again, some of the things with which natural science deals are not subject to motion; for instance, the soul, as is shown in De Anima, and the earth, as is proved in the De Caelo et Mundo. What is more, all natural forms neither come into being nor perish, and for the same reason they are not subject to motion, except accidentally. This is shown in the Metaphysics. Therefore not everything that physics considers is in motion.

7. Again, every creature is mutable for, as Augustine says, true immutability belongs to God alone. So if it is the task of natural science to consider what is in motion, it will be its business to consider all creatures, which clearly appears to be false.

On the contrary, it is the work of natural science to reach conclusions about natural things. Now, natural things are those in which there is a principle of motion; and, as the Metaphysics says, wherever there is motion there must be matter. So natural science treats of what is in motion and matter.

Moreover, these must be some speculative science dealing with what is in matter and motion, for otherwise the teaching of philosophy, which is knowledge of being, would be incomplete. Now no other speculative science treats of these things, for neither mathematics nor metaphysics does so. Therefore, natural science treats of them.

Moreover, the fact is clear from the statements of the Philosopher in the Metaphysics and the Physics.

Reply: It was the difficulty of this problem that drove Plato to posit Ideas. Believing that all sensible things were always in flux, as Cratylus and Heraclitus taught, he thought there can be no science concerning them, as the Philosopher says in the Metaphysics. So he claimed that there were substances separated from the sense world, which might serve as the objects of science and of definitions. He made this mistake because he failed to distinguish what is essential from what is accidental. For it happens that by accident even the wise often fall into error, as is said in the Sophistic Refutations. Now, as is shown in the Metaphysics, we find in a sensible substance both the whole or the composite itself, and also its nature (ratio) or form; and it is the composite that is essentially generated and corrupted and not the nature or form, except accidentally. As the Metaphysics says, “It is not house that is made, but this house.

Now anything can be thought of without all the items that are not essentially related to it. Consequently, forms and natures, though belonging to things existing in motion, are without motion when they are considered in themselves; and so they can be the objects of sciences and of definitions, as the Philosopher says. As he proves, the sciences of sensible reality are not based upon the knowledge of certain substances separated from the sense world.

Natures of this kind, which are the objects of the sciences of real beings, are thought of without motion; and so they must be thought of without those conditions by reason of which motion belongs to mobile things. Now, because every motion is measured by time, and the primary motion is local motion (for without it there is no other motion), a thing must be subject to motion inasmuch as it exists here and now; and it exists under these conditions insofar as it is individuated by matter having determinate dimensions. Consequently, natures of this kind, which make possible sciences of things subject to motion, must be thought of without determinate matter and everything following upon such matter; but not without indeterminate matter, because on its notion depends the notion of form that determines matter to itself. Thus the nature of man, which his definition signifies and which is the object of science, is considered without this flesh and these bones, but not absolutely without flesh and bones. And because individuals include determinate matter in their nature, whereas universals include common matter, as is said in the Metaphysics, the above-mentioned abstraction is not said to be the abstraction of form from matter absolutely, but the abstraction of the universal from the particular.

Natures of this sort, thus abstracted, can be considered in two ways. First, in themselves; and then they are thought of without motion and determinate matter. This happens to them only by reason of the being they have in the intellect. Second, they can be viewed in relation to the things of which they are the natures; and these things exist with matter and motion. Thus they are principles by which we know these things, for everything is known through its form. Consequently, in natural science we know mutable and material things existing outside the soul through natures of this kind; that is to say, natures that are immobile and considered without particular matter.

Replies to opposing arguments:

Reply to 1. Matter is the principle of individuation only insofar as it exists with determinate dimensions, and in this sense natural science indeed abstracts from matter.

Reply to 2. The intelligible form is a thing’s quiddity, for, as the De Anima says, the object of the intellect is the quiddity of a thing. Now, as is said in the Metaphysics, the quiddity of a universal composite, like man or animal, includes within itself common but not particular matter. So the intellect regularly abstracts from determinate matter and its conditions; but in natural science it does not abstract from common matter, although matter itself is considered in natural science only in relation to form. For this reason the natural scientist is more concerned with form than with matter.

Reply to 3. Natural science does not treat of the First Mover as its subject or as part of its subject, but as the end to which natural science leads. Now the end does not belong to the nature of the thing of which it is the end, but it has a relation to it; as the end of a line is not the line but is related to it. So also the First Mover is of a different nature from natural things, but it is related to them because it moves them. So it falls under the consideration of natural science, not in itself, but insofar as it is a mover.

Reply to 4. Science treats of something in two ways: in one way, primarily and principally; and in this sense science is concerned universal natures, which are its very foundation. In another way it treats of something secondarily, as by a sort of reflection; and in this sense it is concerned with the things whose natures they are, inasmuch as, using the lower powers, it relates those natures to the particular things possessing them. For a knower uses a universal nature both as a thing known and as a means of knowing. Thus, through the universal nature of man we can judge of this or that particular man. Now, all universal natures of things are immutable; and so, in this respect, all science is concerned with what is necessary. But some of the things possessing these natures are necessary and immutable, whereas others are contingent and subject to movement, and in this respect sciences are said to be concerned with the contingent and mutable.

Reply to 5. Although a universal is not mutable, it is nevertheless the nature of a mutable thing.

Reply to 6. Although the soul and other natural forms are not themselves subject to motion, they are moved accidentally, and they are, moreover, the perfections of mutable things; and for this reason they come within the domain of natural science. But even though the earth as a whole is not moved (for it happens to be in its natural place, where a thing is at rest in virtue of the same nature through which it is moved to a place), nevertheless, when its parts are outside their proper place, they are moved to a place. Thus the earth falls within the domain of natural science both by reason of the immobility of the whole earth and by reason of the movement of its parts.

Reply to 7. The mutability characteristic of all creatures is not with respect to any natural motion, but with respect to their dependence on God, separation from whom entails destruction of their very being. And that dependence falls under the consideration of metaphysics rather than under that of natural philosophy. Spiritual creatures, moreover, are mutable only with regard to choice; and this sort of motion is not the concern of the natural philosopher but rather of the metaphysician.


Does Mathematics Treat, Without Motion and Matter, of What Exists in Matter?

We proceed as follows to the third article:

It seems that mathematical thinking does not treat, without motion and matter, of what exists in matter, for:

1. Since truth consists in the conformity of thing to intellect, there must be falsehood whenever we think of something otherwise than it is. If then in mathematics we consider what is in matter in abstraction from matter, we will consider it falsely; and so mathematics will not be a science, for every science is concerned with what is true.

2. Again, as the Philosopher states, every science has the task of considering a subject and the parts of the subject. Now in actual existence matter is a part of all material things. So it is impossible for a science to treat of what is in matter without treating of matter.

3. Again, all straight lines are specifically the same. But the mathematician treats of straight lines by numbering them; otherwise he would not treat of the triangle and the square. It follows that he considers lines as specifically the same and numerically different. But it is clear from the above that matter is the principle differentiating things specifically the same. So the mathematician treats of matter.

4. Again, no science completely abstracting from matter demonstrates through a material cause. But in mathematics some demonstrations are made which can only be reduced to a material cause, as when we demonstrate something about a whole by its parts. For, as the Physics says, parts are the matter of the whole. Thus in the Posterior Analytics the demonstration that the angle in a semi-circle is a right angle from the fact that each of its two parts is half of a right angle, is reduced to a material cause. Therefore, mathematics does not entirely abstract from matter.

5. Again, motion cannot exist without matter. But the mathematician ought to consider motion, because, since motion is measured relative to space, to consider the quantity of space, which pertains to the mathematician, and the quantity of motion, has the same nature and belongs to the same science. Therefore, the mathematician does not entirely leave matter out of consideration.

6. Again, astronomy is a part of mathematics, and so too is the science of the moved sphere, the science of weights, and music, all of which treat of motion and mobile things So mathematics does not entirely abstract from matter and motion.

7. Again, natural science is entirely concerned with matter and motion. But some conclusions are demonstrated alike by the mathematician and the natural scientist, for instance, whether the earth is round and whether it is in the middle of the universe. Therefore, mathematics cannot entirely abstract from matter. If it be said that mathematics abstracts only from sensible matter, the contrary seems true. Sensible matter seems to be particular matter, because what the senses perceive are particular things, and all the sciences abstract from this kind of matter. So mathematical thinking should not be called more abstract than that of the other sciences.

8. Again, the Philosopher says that there are three branches of study: the first concerns what is mutable and corruptible, the second what is mutable and incorruptible, and the third what is immutable and incorruptible. As Ptolemy explains, the first is natural science the third divine science, and the second mathematics. Therefore mathematics concerns what is mutable.

To the contrary is the Philosopher’s statement in the Metaphysics.

Moreover, some things, although existing in matter, do not contain matter in their definition; for instance, curve, which differs in this respect from snub. Now philosophy should treat of all beings. Hence some part of philosophy must consider beings of this sort; and this is mathematics, for this does not belong to any other part.

Moreover, what is prior from the point of view of the intellect can be considered without what is posterior. Now mathematicals are prior to natural things existing in matter and motion, for the latter are so related to mathematicals that they add something to them, as is said in the De Caelo et Mundo. Therefore, mathematical investigation can be without matter and motion.

Reply: In order to throw light on this question we must understand how the intellect in its operation is able to abstract.

We must realize that, as the Philosopher says, the intellect has two operations, one called the “understanding of indivisibles,” by which it knows what a thing is, and another by which it joins and divides, that is to say, by forming affirmative and negative statements. Now these two operations correspond to two principles in things. The first operation concerns the nature itself of a thing, in virtue of which the object known holds a certain rank among beings, whether it be a complete thing, like some whole, or an incomplete thing, like a part or an accident. The second operation has to do with a thing’s being (esse), which results from the union of the principles of a thing in composite substances, or, as in the case of simple substances, accompanies the thing’s simple nature.

Now, since the truth of the intellect results from its conformity with reality, it is clear that in this second operation the intellect cannot truthfully abstract what is united in reality, because the abstraction would signify a separation with regard to the very being of the thing. For example, if I abstract man from whiteness by saying, “Man is not white,” I signify that there is a separation in reality. So if in reality man and whiteness are not separate, the intellect will be false. Through this operation, then, the intellect can truthfully abstract only those things that are separate in reality, as when we say, “Man is not an ass.”

Through the first operation, however, we can abstract things that are not separate in reality; not all, it is true, but some. For, since everything is intelligible insofar as it is in act, as the Metaphysics says, we must understand the nature itself or the quiddity of a thing either inasmuch as it is a certain act (as happens in the case of forms themselves and simple substances); or through that which is its act (as we know composite substances through their forms); or through that which takes the place of act in it (as we know prime matter through its relation to form, and a vacuum through the absence of a body in place). And it is from this that each nature is given its definition.

Therefore, when the nature itself is related to, and depends on something else, with regard to that which forms the definition (ratio) of the nature, and through which the nature itself is understood, clearly we cannot know the nature without that other thing. This is true whether they are connected as a part is united to a whole (as we cannot know foot without knowing animal, because that whereby foot has the nature of foot depends on that whereby animal is animal); or whether they are connected as form is united to matter, or as one part to another part, or as accident to subject (as we cannot know snub without nose); or even whether they are separated in reality (as we cannot know father without knowing son, although these relationships are found in different things). But if one thing does not depend on another with regard to that which forms the definition of the nature, then the intellect can abstract the one from the other so as to know it without the other. This is true not only if they are separated in reality, like man and stone, but also if they are united in reality, whether they are joined as part and whole (as letter can be understood without syllable, but not vice versa, and animal without foot, but not conversely); or even if they are joined as form is united to matter and accident to subject (as whiteness can be understood without man and vice versa).

Accordingly, through its various operations the intellect distinguishes one thing from another in different ways. Through the operation by which it composes and divides, it distinguishes one thing from another by understanding that the one does not exist in the other. Through the operation, however, by which it understands what a thing is, it distinguishes one thing from another by knowing what one is without knowing anything of the other, either that it is united to it or separated from it. So this distinction is not properly called separation, but only the first. lt is correctly called abstraction, but only when the objects, one of which is known without the other, are one in reality. For if we consider animal without considering stone, we do not say that we abstract animal from stone.

It follows that since, properly speaking, we can only abstract objects united in existence, there are two sorts of abstraction corresponding to the two modes of union mentioned above, namely, the union of part and whole, and the union of form and matter. The first is that in which we abstract form from matter, and the second is that in which we abstract a whole from its parts.

Now a form can be abstracted from matter if the essential nature of the form does not depend on that particular kind of matter; but the intellect cannot abstract form from the kind of matter upon which the form depends according to its essential nature. Consequently, because all accidents are related to the underlying substance as form to matter, and because it is the nature of every accident to depend upon substance, no form of this kind can be separated from substance. But accidents befall substance in a definite order. Quantity comes to it first, then quality, after that passivities (passiones) and actions. So quantity can be thought of in substance before the sensible qualities (because of which matter is called sensible) are considered in it. Quantity, then, according to its essential nature does not depend upon sensible matter but only upon intelligible matter. For, after accidents have been abstracted, substance is intelligible only to the intellect, because it is beyond the sense powers to comprehend substance. And abstract objects of this kind are the concern of mathematics; it treats of quantities and the properties of quantity, such as figures and the like.

Moreover, we cannot abstract a whole from just any parts. For there are some parts upon which the nature of the whole depends, namely, when the being of a particular whole consists in the composition of particular parts. It is in this way that a syllable is related to letters and a mixed body to the elements. Parts of this sort, which are necessary for understanding the whole because they enter into its definition, are called parts of the species and of the form. There are some parts, however, that are accidental to the whole as such. The semicircle, for instance, is related to the circle in this way, for it is accidental to a circle that it be divided into two or more equal or unequal parts. But it is not accidental to a triangle that three lines are designated in it, for because of this a triangle is a triangle. Similarly, it is an essential characteristic of man that there be found in him a rational soul and a body composed of the four elements. So man cannot be understood without these parts and they must be included in his definition; so they are parts of his species and form. But finger, foot, and hand, and other parts of this kind are outside the definition of man; and thus the essential nature of man does not depend on them and he can be understood without them. For whether or not he has feet, as long as he is constituted of a rational soul and a body composed of the elements in the proper mixture required by this sort of form, he will be a man. These parts are called parts of matter: they are not included in the definition of the whole, but rather the converse is true. This is how all determinate (signatae) parts are related to man; for instance, this soul, this body, this nail, this bone, etc. These indeed are parts of the essence of Socrates and Plato, but not of man precisely as man; and therefore the intellect can abstract man from these parts. And this is the abstraction of the universal from the particular.

So there are two abstractions of the intellect. One corresponds to the union of form and matter or accident and subject. This is the abstraction of form from sensible matter. The other corresponds to the union of whole and part; and to this corresponds the abstraction of the universal from the particular. This is the abstraction of a whole, in which we consider a nature absolutely, according to its essential character, in independence of all parts that do not belong to the species but are accidental parts. But we do not find abstractions opposed to these, by which a part is abstracted from a whole by the intellect if it is one of the parts of matter in whose definition the whole is included, or it can even exist without the whole if it is one of the parts of the species, for instance, a line without a triangle, a letter without a syllable, or an element without a mixed body. But in the case of things that can exist separately, separation rather than abstraction obtains. Similarly, when we say from is abstracted from matter, we do not mean substantial form, because substantial form and the matter correlative to it are interdependent, so that one is not intelligible without the other, because the appropriate act is in its appropriate matter. Rather, we mean the accidental forms of quantity and figure, from which indeed sensible matter cannot be abstracted by the intellect, because sensible qualities cannot be understood unless quantity is presupposed, as is clear in the case of surface and color. And neither can we understand something to be the subject of motion unless we understand it to possess quantity. Substance, however, which is the intelligible matter of quantity, can exist without quantity. Consequently, the consideration of substance without quantity belongs to the order of separation rather than to that of abstraction.

We conclude that there are three kinds of distinction in the operation of the intellect. There is one through the operation of the intellect joining and dividing which is properly called separation and this belongs to divine science or metaphysics. There is another through the operation by which the quiddities of things are conceived which is the abstraction of form from sensible matter, and this belongs to mathematics. And there is a third through the same operation which is the abstraction of a universal from a particular, and this belongs to physics and to all the sciences in general, because science disregards accidental features and treats of necessary matters. And because certain men (for example, the Pythagoreans and the Platonists) did not understand the difference between the last two kinds of distinction and the first, they fell into error, asserting that the objects of mathematics and universals exist separate from sensible things.

Replies to Opposing Arguments:

Reply to 1. When the mathematician abstracts he does not consider something otherwise than it is. Thus, he does not think that a line exists without sensible matter, but he treats of a line and its properties without considering sensible matter. So there is no disagreement between his intellect and reality, because even in reality what belongs to the nature of a line does not depend upon that which makes matter sensible, but vice versa. Consequently, it is evident that “there is no error in the one who abstracts,” as is said in the Physics.

Reply to 2. By “material” is meant not only that which has matter as a part, but also that which exists in matter; and in this way sensible line can be called something material. So this does not prevent a line from being understood without matter. For sensible matter is not related to a line as a part, but rather as the subject in which it exists, and this is also the case with a surface or body. Obviously, the mathematician does not treat of the kind of body that is in the category of substance, whose parts are matter and form, but rather the body in the category of quantity, constituted by three dimensions. Body, in this sense of the term, is related to body the category of substance (of which physical matter is a part) as accident to its subject.

Reply to 3. Matter is the principle of numerical diversity or inasmuch as, being divided into many parts, and receiving in each part a form of the same nature, it constitutes many individuals of the same species. Now matter can be divided only if we presuppose quantity in it; if that is taken away, even substance remains indivisible. So the primary reason for the diversification of things of one species lies in quantity. And this is due to quantity because position, which is the arrangement of parts in place, is contained in its notion as a kind of formal difference. So even when the intellect has abstracted quantity from sensible matter, it is still possible to imagine numerically different things in the same species, for example, several equilateral triangles and several equal straight lines.

Reply to 4. Mathematics does not abstract from every kind of matter but only from sensible matter. Now the parts of quantity that seem to be in a way the basis for a demonstration by means of a material cause are not sensible matter; rather, they pertain to intelligible matter, which indeed is found in mathematics, as is clear in the Metaphysics.

Reply to 5. By its very nature motion is not in the category of quantity, but it partakes somewhat of the nature of quantity from another source, namely, according as the division of motion derives from either the division of space or the division of the thing subject to motion. So it does not belong to the mathematician to treat of motion, although mathematical principles can be applied to motion. Therefore, inasmuch as the principles of quantity are applied to motion, the natural scientist treats of the division and continuity of motion, as is clear in the Physics. And the measurements of motions are studied in the intermediate sciences between mathematics and natural science: for instance, in the science of the moved sphere and in astronomy.

Reply to 6. Simple bodies and their properties remain in composite bodies although in a different way, as the proper qualities of the elements and their proper movements are found in a mixed body. What is proper to composite bodies, however, is not found in simple bodies. And so it is that the more abstract and simple the objects of a science are, the more applicable its principles are to the other sciences. Thus the principles of mathematics are applicable to natural things, but not visa versa, because physics presupposes mathematics; but the converse is not true, as is clear in the De Caelo et Mundo. So there are three levels of sciences concerning natural and mathematical entities. Some are purely natural and treat of the properties of natural things as such, like physics, agriculture, and the like. Others are purely mathematical and treat of quantities absolutely, as geometry considers magnitude and arithmetic numbers. Still others are intermediate, and these apply mathematical principles to natural things; for instance, music, astronomy, and the like. These sciences, however, have a closer affinity to mathematics, because in their thinking that which is physical is, as it were, material, whereas that which is mathematical is, as it were, formal. For example, music considers sounds, not inasmuch as they are sounds, but inasmuch as they are proportionable according to numbers; and the same holds in other sciences. Thus they demonstrate their conclusions concerning natural things, but by means of mathematics. Therefore nothing prevents their being concerned with sensible matter insofar as they have something in common with natural science, but insofar as they have something in common with mathematics they are abstract.

Reply to 7. Because the intermediate sciences mentioned above have something in common with natural science as regards what is material in their procedure, but differ from it as regards what is formal in it, nothing prevents these sciences from occasionally having the same conclusions as natural science. Nevertheless, they do not use the same means of demonstration, unless the sciences are mixed and one occasionally uses what belongs to another, as the natural scientist proves that the earth is round from the movement of heavy bodies, while the astronomer proves it by considering eclipses of the moon.

Reply to 8. As the Commentator says, the Philosopher there did not intend to distinguish between the speculative sciences, because the natural scientist treats of everything subject to motion, whether it be corruptible or incorruptible, while the mathematician as such does not treat of anything subject to motion. But he intended to distinguish between the things studied by the speculative sciences, which must be treated separately and in order, although these three sorts of things can be apportioned to the three sciences. For incorruptible and immobile beings pertain precisely to the metaphysician. However, mobile and incorruptible beings, owing to their uniformity and regularity, can be determined in their movements by mathematical principles; this cannot be said of beings that are mobile and corruptible. Therefore, as Ptolemy says, the second kind of beings is ascribed to mathematics through astronomy, while the third kind remains the proper domain of natural science alone.


Does Divine Science Treat of What Exists Without Matter and Motion?

We proceed as follows to the fourth article:

It seems that divine science does not treat of things separate from motion and matter, for:

1. Divine science seems to he especially concerned with God. Now we can come to know God only by way of his visible effects, which are created in matter and motion, as it is said in the Epistle to the Romans, “The invisible things of him, from the creation of the world, are clearly seen, being understood by the things that are made.” Therefore, divine science does not abstract from matter and motion.

2. Again, that to which motion in some way belongs is not entirely separate from motion and matter. But motion in some way belongs to God. Thus it is said in Wisdom that the Spirit of Wisdom is “mobile” and “more mobile than all mobile things.” And Augustine says that God moves himself without time and place. Plato also asserted that the First Mover moves itself. Therefore divine science, which treats of God, is not entirely separate from motion.

3. Again, divine science must treat not only of God but also of angels. But angels change both with regard to choice, because they became bad after having been good, and also with regard to place, as is evident in the case of those who are sent as messengers. So the objects of divine science are not entirely separated from motion.

4. Again, as the Commentator seems to say in the beginning of the Physics, every being is either pure matter, or pure form, or a composite of matter and form. But an angel is not a pure form, because then he would be pure act, which is true of God alone. Neither is he pure matter. So he is a composite of matter and form. Therefore divine science does not abstract from matter.

5. Again, divine science, the third part of speculative philosophy, is the same as metaphysics, whose subject is being, and especially substantial being. This is clear in the Metaphysics. But being and substance do not abstract from matter; otherwise there would be no material being. So divine science does not abstract from matter.

6. Again, according to the Philosopher, it is the business of a science to consider not only a subject but also the divisions and attributes of that subject. Now, as we have said, being is the subject of divine science. Therefore it is the business of this science to treat of all beings. But matter and motion are beings. Therefore they come under the consideration of metaphysics, and so divine science does not abstract from them.

7. Again, divine science demonstrates by means of three causes: efficient, formal, and final, as the Commentator says, But we cannot consider an efficient cause without taking motion into account; and the same thing is true of a final cause, as the Metaphysics says. Thus, because the objects of mathematics are immobile, there are no demonstrations through these causes in that science. Consequently, divine science does not abstract from motion.

8. Again, in theology we treat of the creation of the heavens and the earth, of acts of men, and many similar things that involve matter and motion. So theology does not seem to abstract from matter and motion.

On the contrary, the Philosopher says in the Metaphysics that “first philosophy deals with things that can exist separately,” that is, from matter, “and with immobile things.” Now first philosophy is divine science, as he says in the same place. Therefore divine science abstracts from matter and motion.

Moreover, the most excellent science deals with the most excellent beings. But the most excellent science is divine science. Therefore, since immaterial and immobile beings are the most excellent, divine science will treat of them.

Moreover, the Philosopher says in the beginning of the Metaphysics that divine science concerns first principles and causes. Now these are immaterial and immobile. Therefore things of this sort are the objects of divine science.

Reply: In order to throw light on this question we must understand what science should be called divine science. We must realize indeed that if a science considers a subject-genus, it must investigate the principles of that genus, since science is perfected only through knowledge of principles, as the Philosopher explains in the beginning of the Physics. Now there are two kinds of principles. (1) Some are complete natures in themselves and nevertheless they are the principles of other things, as the heavenly bodies are principles of lower bodies and simple bodies are principles of mixed bodies. In the sciences, therefore, we study them not only insofar as they are principles, but also insofar as they are certain things in themselves. And for this reason they are considered not only in the science of the beings of which they are the principles, but also in a separate science. Thus there is a branch of natural science treating of heavenly bodies distinct from that treating of lower bodies, and there is one treating of the elements distinct from that treating of mixed bodies. (2) There are some principles, however, that are not complete natures in themselves, but only principles of natures, as unity is the principle of number, point the principle of line, and form and matter principles of natural bodies. Principles of this sort, then, are investigated only in the science dealing with the things of which they are principles.

Now just as there are certain common principles of any particular genus extending to all the principles of that genus, so too all beings, inasmuch as they share in being, have certain principles that are the principles of all beings. And as Avicenna says,” these principles can be called common in two ways, (1) first, by predication, as when I say that form is common to all forms because it is predicated of all; (2) second, by causality, as we say that the sun, which is numerically one, is the principle of all things subject to generation.

Now there are principles common to all beings not only in the first way (in this sense the Philosopher says that all beings have proportionately the same principles), but also in the second way, so that there are certain beings, each numerically one, which are the principles of all things. Thus the principles of accidents are reducible to the principles of substance, and the principles of perishable substances are reducible to imperishable ones, with the result that all beings are reducible to certain principles in a definite graded order.

And since the principle of the being of all things must be being in the highest degree as the Metaphysics says, these principles must be most perfect and therefore supremely in act, so that they have no potentiality whatsoever, or the least possible, because actuality is prior to, and more excellent than potentiality, as the Metaphysics says. For this reason they must be free from matter, which is in potency, and free from motion, which is actuality of that which exists in potency. Divine beings are of this sort, “because if the divine exists anywhere, it exists especially in such a nature” (that is to say, in a nature that is immaterial and immutable), as is sad in the Metaphysics.

Accordingly, because these divine beings are the principles of all things and nevertheless they are complete natures in themselves, they can be studied in two ways: (1) first, insofar as they are the common principles of all things, and (2) second insofar as they are beings in their own right. But even though these first principles are most evident in themselves, our intellect regards them as the eye of an owl does the light of the sun, as the Metaphysics says. We can reach them by the light of natural reason only to the extent that their effects reveal them to us. It was in this way that the philosophers came to know them as is clear from the Epistle to the Romans: “The invisible things of God... are clearly seen, being understood by the things that are made.” Philosophers, then, study these divine beings only insofar as they are the principles of all things. Consequently, they are the objects of the science that investigates what is common to all beings, which has for its subject being as being. The philosophers call this divine science.

There is, however, another way of knowing beings of this kind, (a) not as their effects reveal them, but (b) as they reveal themselves. The Apostle mentions this way in his First Epistle to the Corinthians: “So the things also that are of God no man knows, but the Spirit of God. Now we have received not the spirit of this world, but the Spirit that is of God, that we may understand.” And again, “But to us God has revealed them by his Spirit.” In this way we consider divine beings as they subsist in themselves and not only inasmuch as they are the principles of things.

Accordingly, there are two kinds of theology or divine science. (1) There is one that treats of divine things, not as the subject of the science but as the principles of the subject. This is the kind of theology pursued by the philosophers and that is also called metaphysics. (2) There is another theology, however, that investigates divine things for their own sakes as the subject of the science. This is the theology taught in Sacred Scripture.

Both treat of beings that exist separate from matter and motion, but with a difference, for something can exist separate from matter and motion in two distinct ways: (1) first, because by its nature the thing that is called separate in no way can exist in matter and motion, as God and the angels are said to be separate from matter and motion. (2) Second, because by its nature it does not exist in matter and motion; but it can exist without them, though we sometimes find it with them. In this way being, substance, potency, and act are separate from matter and motion, because they do not depend on them for their existence, unlike the objects of mathematics, which can only exist in matter, though they can be understood without sensible matter.

Thus philosophical theology investigates beings separate in the second sense as its subjects, and beings separate in the first sense as the principles of its subject. But the theology of Sacred Scripture treats of beings separate in the first sense as its subjects, though it concerns some items in matter and motion insofar as this is needed to throw light on divine things.

Replies to Opposing Arguments:

Reply to 1. When something is incorporated into a science only to throw light on something else, it does not belong to the science essentially, but, in a way, incidentally, as some mathematics are incorporated into the natural sciences. In this way nothing prevents some things in matter and motion being in divine science.

Reply to 2. We do not attribute motion to God properly, but by a kind of metaphor, and this in two ways, first, according as the operation of the intellect or will is improperly called motion; and in this way a person is said to move himself when he knows or loves himself. ln this sense, as the Commentator says, the statement of Plato is true, that the First Mover moves himself because he knows and loves himself. Second, according as the flowing forth of effects From their causes can be called a procession or motion of cause to effect insofar as the likeness of the cause is left in the effect itself; and so the cause, which previously existed in itself, afterward comes to be in the effect through its likeness. And in this way God, who has communicated his likeness to all creatures, in a certain respect is said to be moved by all of them or to go forward to all things. Dionysius frequently uses this manner of speaking. This also seems to be the meaning of the statement in Wisdom, that “Wisdom is more mobile than all mobile things,” and that “She reaches from end to end mightily.” However, this is not motion in the proper sense the term, and so the argument does not follow.

Reply to 3. Divine science received through divine inspiration does not treat of the angels as its subject, but only as something incorporated into the science to throw light on its subject. For Sacred Scripture treats of the angels just as it does other creatures. In the divine science taught by the philosophers, however, the angels, which they call Intelligences, are considered from the same point of view as the First Cause or God, insofar as they are also secondary principles of things, at least through the movement of the spheres, though the angels themselves are subject to no physical motion. Moreover, motion with respect to choice is reducible to the sense in which the act of the intellect or will is called motion, which is an improper sense of the term, motion being understood as operation. Further, when angels are said to move in place, their motion is not with reference to enclosure in place but with reference to the activity they exercise in this or that place, or with reference to some other relation they have to place, although that relation is absolutely equivocal to that which a localized body has to place. So it is clear that they do not move in the sense in which we say natural things move.

Reply to 4. Act and potency are more common than matter and form. Therefore, even though we do not find the composition of form and matter in the angels we can still find potency and act in them. For matter and form are parts of a thing composed of matter and form; and so we find the composition of matter and form only in things with parts, one of which is related to the other as potency to act. Now what can be, can also not be; and so one part can be found with or without the other; and therefore, as the Commentator says, we find the composition of matter and form only in those things that are by nature corruptible. Nor is the objection valid, that an accident may be eternally conserved in a subject, like shape in the heavens. For a heavenly body cannot exist without such a shape, since shape and all accidents in general follow upon substance as their cause. So a subject is related to its accidents not only as passive potency, but also in a way as an active power; and for this reason some accidents are naturally conserved forever in their subjects. But matter is not the cause of form in this way; and therefore all matter subject to form can cease to be subject to it, unless perhaps an extrinsic cause preserves it; thus we maintain that by the divine power even some bodies composed of contraries, like the bodies of those arisen from the dead, are incorruptible.

Now, since the essence of an angel is incorruptible by its nature, it is not composed of form and matter. But an angel does not exist of himself, and so he is potential to the being (esse) he receives from God. Consequently, the being (esse) received from God is related to his simple essence as act to potency. This is what is meant by saying that angels are composed of what they are (quod est) and that by which they are (quo est); being (esse) is understood as that by which they are and the angelic nature as what they are. However, even if angels were composed of matter and form, they would not be composed of sensible matter, from which both the objects of mathematics must be abstracted and those of metaphysics must be separated.

Reply to 5. We say that being and substance are separate from matter and motion not because it is of their nature to be without them, as it is of the nature of ass to be without reason, but because it is not of their nature to be in matter and motion, although sometimes they are in matter and motion, as animal abstracts from reason, although some animals are rational.

Reply to 6. The metaphysician deals with individual beings too, not with regard to their special natures, in virtue of which they are special kinds of being, but insofar as they share the common character of being. And in this way matter and motion also fall under his consideration.

Reply to 7. Action and passion do not belong to things as they exist in thought but as they exist in reality. Now since the mathematician deals with things that are abstract only in thought, insofar as they come under his consideration they cannot be the principle or the end of motion. So the mathematician does not demonstrate by means of efficient and final causes. But the things the metaphysician deals with are separate, existing in reality, and these can be the principle and end of motion. So nothing prevents his demonstrating by means of efficient and final causes.

Reply to 8. Just as faith, which is in a way the habit of the principles of theology, has for its object the First Truth itself, and yet the articles of faith contain certain other things relating to creatures insofar as they have some connection with the First Truth, in the same way theology is primarily concerned with God as its subject, but it includes many things about creatures as his effects, or as being in some way related to him.



The next question concerns the methods ascribed by Boethius to the speculative sciences. There are four points of inquiry in this connection:

1. Must we proceed according to the mode of reason in natural science, according to the mode of learning in mathematics, and according to the mode of intellect in divine science?

2. Should we entirely abandon the imagination in divine science?

3. Can our intellect behold the divine form itself?

4. Can our intellect behold the divine form by means of some speculative science?


Must we Proceed according to the Mode of Reason in Natural Science, according to the Mode of Learning in Mathematics, and according to the Mode of Intellect in Divine Science?


On the first point we proceed as follows: lt seems that we must no proceed according to the mode of reason in natural science, for:

1. Rational philosophy is contra-distinguished from natural philosophy. But it seems to belong properly to rational philosophy to proceed according to the mode of reason. So this method is not appropriately ascribed to natural philosophy.

2. Again, in the Physics the Philosopher frequently distinguishes between the methods of arriving at rational conclusions and physical conclusions. Therefore it is not the special characteristic of natural science to proceed rationally.

3. Again, what is common to all the sciences should not be reserved to one. But every science proceeds by reasoning, advancing from effects to causes or from causes to effects or from certain signs So this method should not be reserved to natural science.

4. Again, in the Ethics the Philosopher distinguishes the reasoning part of the soul from the scientific part. But natural philosophy belongs to the scientific part. Therefore it is not appropriately said to proceed according to the mode of reason.

On the contrary, the De Spiritu et Anima says that reason is concerned with the forms of bodies. Now it belongs most especially to natural philosophy to consider bodies. Therefore the rational method is appropriately attributed to it.

Moreover, Boethius says: “When reason contemplates some universal nature, using neither imagination nor sense, it nevertheless comprehends imaginable and sensible things.” Now it belongs to the natural philosopher alone to comprehend what is imaginable and sensible. Therefore the rational method is suitably attributed to natural philosophy.


In the second place, it seems inappropriate to say that mathematics proceeds according to the mode of learning, for:

1. Learning seems to be nothing else than the receiving knowledge. But we receive scientific knowledge in all branches of philosophy, because all proceed by means of demonstration. So it is common to all parts of philosophy to proceed according to the mode of learning; and so this procedure should not be made exclusive to mathematics.

2. Again, the more certain something is, the easier it seems to learn it. But natural things seem to be more certain than mathematics because they are apprehended by the senses, from which all our knowledge takes its origin. Therefore this method belongs to the natural philosopher rather than to the mathematician.

3. Again, as the Metaphysics says, in the sciences we begin at the point from which we learn more easily. But learning begins with logic, which must be mastered before mathematics and all the other sciences. Therefore it belongs to logic rather than to the other sciences to proceed according to the mode of learning.

4. Again, the methods of natural and divine science are taken from powers of the soul, namely from reason and intellect. Therefore in the same way the method of mathematics ought to be taken from some power of the soul. So it is not appropriate to say that its method is to proceed according to the mode of learning.

On the contrary, to proceed according to the mode of learning is to proceed by demonstration and with certitude. But as Ptolemy says, “Mathematics alone, if one applies himself diligently to it, will give the inquirer after knowledge firm and unshaken certitude by demonstrations carried out with unquestionable methods.” Therefore it is most characteristic of mathematics to proceed according to the mode of learning. Moreover, this is evident from the Philosopher who, in several places in his works, calls the mathematical sciences disciplines.


In the third place, it seems that it is not appropriate to divine science to proceed according to the mode of intellect, for:

1. According to the Philosopher,” there is understanding (intellectus) of principles, whereas there is science of conclusions. But principles alone are not considered in divine science; some conclusions are also considered. Therefore to proceed according to the mode of intellect is not appropriate to divine science.

2. Again, we cannot proceed intellectually with regard to those things that transcend every intellect. But divine things transcend every intellect, as Dionysius and the Philosopher say. Therefore they cannot be dealt with intellectually.

3. Again, Dionysius says that angels have intellectual power inasmuch as they do not gather their divine knowledge from what is sensible and divided; but, as he adds, this is beyond the power of the soul. Therefore, since the divine science that is now under discussion is a science belonging to the human soul, it appears that its proper method is not to proceed intellectually.

4. Again, theology seems particularly concerned with the things of faith. But understanding (intelligere) is the goal of the things of faith. Thus it is said in lsaiah, according to another version, “Unless you believe, you will not understand.” So we should not say that proceeding intellectually about divine things is the method of theology but the goal.

On the contrary, the De Spiritu et Anima says that intellect (intellectus) has for its object created spirits, while understanding (intelligentia) has for its object God himself. Now divine science is principally concerned with them. Therefore it seems proper to it to proceed intellectually.

Moreover, the method of a science must correspond to its subject matter. But divine things are intelligible in virtue of themselves. Therefore the method appropriate to divine science is to proceed intellectually.

Reply: To the first question (a) I reply that a method of proceeding in the sciences is called rational in three ways:

ln one way, because of the principles from which we begin; for instance, when we proceed to prove something beginning with mental beings, like genus, species, opposite, and concepts of this sort, which the logicians study. In this sense a method will be called rational when in a science we use the propositions taught in logic; namely, when we use logic as having a teaching function in the other sciences. But this method of proceeding cannot belong properly to any particular science: it will fall into error unless it proceeds from its own proper principles. However, logic and metaphysics may properly and suitably use this method, because both are universal sciences and in a sense treat of the same subject.

In a second way, a method is called rational because of the end that terminates the thinking process. (1) For the ultimate end that rational inquiry ought to reach is the understanding of principles, in which we resolve our judgments. And when this takes place, it is not called a rational procedure or proof but a demonstration. (2) Sometimes, however, rational inquiry, cannot arrive at the ultimate end, but stops in the course of the investigation itself; that is to say, when several possible solutions still remain open to the investigator. This happens when we proceed by means of probable arguments, which by their nature produce opinion or belief, but not science. In this sense, rational method is opposed to demonstrative method. We can proceed by this rational method in all the sciences, preparing the way for necessary, proofs by probable arguments. This is another use of logic in the demonstrative sciences; not indeed as having a teaching function, but as being an instrument. ln these two ways, then, a method is called rational from rational science, for, as the Commentator says, in both of them logic (which is another name for rational science) is used in the demonstrative sciences.

In a third way, a method is called rational from the rational power, that is, inasmuch as in our procedure we follow the manner proper to the rational soul in knowing, and in this sense the rational method is proper to natural science. For in its procedures natural science keeps the characteristic method of the rational soul in two ways. (1) First, in this respect, that just as the rational soul receives from sensible things (which are more knowable relatively to us) knowledge of intelligible things (which are more knowable in their nature), so natural science proceeds from what is better known to us and less knowable in its own nature. This is evident in the Physics. Moreover, demonstration by means of a sign or an effect is used especially in natural science. (2) Secondly, natural science uses a rational method in this respect, that it is characteristic of reason to move from one thing to another; and this method is observed particularly in natural science, where we go from the knowledge of one thing to the knowledge of another; for example, from the knowledge of an effect to the knowledge of its cause. (a) And the procedure in natural science is not only a movement from one thing to another distinct from it in the mind and not in reality, as when we go from the concept animal to the concept man. In the mathematical sciences we proceed only by means of what is of the essence of a thing, since they demonstrate only through a formal cause. In these sciences, therefore, we do not demonstrate something about one thing through another thing, but through the proper definition of that thing. It is true that some demonstrations about the circle are made by means of the triangle or vice versa, but this is only because the triangle is potentially in the circle and vice versa. (b) But in natural science, where demonstration takes place through extrinsic causes, something is proved of one thing through another thing entirely external to it. So the method of reason is particularly observed in natural science; and on this account natural science among all the others is most in conformity with the human intellect. Consequently, we say that natural science proceeds rationally, not because this is true of it alone, but because it is especially characteristic of it.

Replies to Opposing Arguments:

Reply to 1. That argument is based on the method that is called rational in the first way. In this sense a rational method is proper to rational and divine science, but not to natural science.

Reply to 2. That argument is based on the method that is called rational in the second way.

Reply to 3. The method of reason is observed in all the sciences insofar as they proceed from one item to another that is mentally distinct from it, but not in the sense that they go from one thing to another thing. As has been said, that is proper to natural science.

Reply to 4. In that place the Philosopher considers the reasoning and deliberative parts of the soul to be identical: so it is clear that they are related to the second mode of rational procedure mentioned above. In the same place, moreover, because of their contingency he assigns human actions, which are the objects of moral science, to the reasoning or deliberative part of the soul. From what has been said, then, we can gather that the first mode of rationality is most characteristic of rational science, the second of moral science, and the third of natural science.

To the second question (b) I reply that mathematical science is said to proceed according to the mode of learning, not because it alone does so, but because this is especially characteristic of it. For, since learning is nothing else than the taking of knowledge from another, we are said to proceed according to the mode of learning when our procedure leads to certain knowledge, which is called science. Now this occurs particularly in the mathematical sciences. Because mathematics is situated between natural and divine science, it is more certain than either.

It is more certain than natural science because its investigation is not bound up with motion and matter, while the investigation of natural science centers upon matter and motion. Now from the very fact that natural science deals with matter, its knowledge depends upon many factors, upon the consideration of matter itself, of form, and of the material dispositions and properties accompanying form in matter. And whenever there are many factors to be considered in order to know something, knowledge is more difficult. Thus the Posterior Analytics says that a science is less certain that results from adding on some item, as geometry adds something to arithmetic. If the inquiry in a science is about things that are mobile and lack uniformity, its knowledge is less exact because its demonstrations are often valid only in the majority of cases, owing to the fact that things sometimes happen differently. So, too, the more a science draws close to particulars (as do practical sciences like medicine, alchemy, and ethics), the less certain they can be because of the many factors to be taken into account in these sciences, the omission of any one of which will lead to error, and also because of their variability.

The method of mathematics is also more certain than the method of divine science, because the objects of divine science are further removed from sensible things, from which our knowledge takes its origin. This is true both in the case of the separate substances (to which our knowledge of the sense world gives us inadequate access), and also in the case of the principles common to all things (which are most universal and therefore furthest removed from the particular things falling under the senses). But mathematical entities do fall under the senses and they are objects of our imagination; for example, figures, lines, numbers, and the like. So the human intellect, which takes its knowledge from images, knows these things with greater ease and certainty than it does a separate Intelligence, or even the nature of substance, act, potency, and the like.

It is clear, then, that mathematical inquiry, is easier and more certain than physical and theological, and much more so than that of the other sciences that are practical, and for this reason it is said especially to proceed according to the mode of learning. This is what Ptolemy asserts in the beginning of the Almagest: “Let us call the other two kinds of theoretical knowledge opinion rather than science: theology because of its obscurity and incomprehensibility, physics because of the instability and obscurity of matter. The mathematical type of investigation alone will give the inquirer firm and unshaken certainty through demonstrations carried out by unquestionable methods.”

Replies to Opposing Arguments.

Reply to 1. Although we learn in all the sciences, nevertheless, as we have said, we do so with greater ease and certitude in mathematics.

Reply to 2. Natural things come under the senses; but because of their instability when they begin to exist in reality they do not have the great certitude of the objects of mathematics. These latter are not subject to change; and yet they exist in sensible matter, and as such they can come under the senses and imagination.

Reply to 3. In learning we begin with what is easier, unless necessity dictates otherwise. For sometimes in learning it is necessary to start, not with what is easier, but with that on which the knowledge of subsequent matters depends. That is why in acquiring knowledge we must begin with logic, not because it is easier than other sciences (for it involves the greatest difficulty, concerned as it is with second intentions), but because the sciences depend on it inasmuch as it teaches the method of proceeding in all the sciences. And, as the Metaphysics says, we must know the method of science before science itself.

Reply to 4. The method of the sciences is taken from the powers of the soul because of the way in which these powers operate. So the methods of the sciences do not correspond to the soul’s powers, but rather to the ways in which these powers can operate, and these are diversified not only according to the powers, but also according to their objects. So it is not necessary that the method of every science be named after a power of the soul. However, we can say that just as the method of physics is taken from reason inasmuch as it gets its objects from the senses, and the method of divine science is taken from the intellect inasmuch as it understands something purely and simply (nude), so also the method of mathematics can be taken from reason inasmuch as it obtains its objects from the imagination.

To the third question (c) I reply that just as we attribute the rational method to natural philosophy because it adheres most closely to the method of reason, so we attribute the intellectual method to divine science because it adheres most closely to the method of intellect. Now reason differs from intellect as multitude does from unity. Thus Boethius says that reasoning is related to understanding as time to eternity and as a circle to its center. For it is distinctive of reason to disperse itself in the consideration of many things, and then to gather one simple truth from them. Thus Dionysius says, “Souls have the power of reasoning in that they approach the truth of things from various angles, and in this respect they are inferior to the angels; but inasmuch as they gather a multiplicity into unity they are in a way equal to the angels.” Conversely, intellect first contemplates a truth one and undivided and in that truth comprehends a whole multitude, as God, by knowing his essence, knows all things. Thus Dionysius says: “Angelic minds have the power of intellect in that they understand divine truths in a unified way.”

It is clear, then, that rational thinking ends in intellectual thinking, Following the process of analysis, in which reason gathers one simple truth from many things. And again, intellectual thinking is the beginning of rational thinking, following the process of synthesis, in which the intellect comprehends a multiplicity in unity. So the thinking that is the terminus of all human reasoning is supremely intellectual.

Now all rational thinking in all the sciences, following the way of analysis, terminates in the knowledge of divine science. For, as we have said, reason sometimes advances from one thing to another in the order of reality; for example, when a demonstration is made through external causes or effects, by synthesis when we go from causes to effects, by analysis when we proceed from effects to causes, for causes are more simple, unchangeable, and uniformly constant than their effects. Consequently, the ultimate end of analysis in this process is attainment d the highest and most simple causes, which are the separate substances. At other times, however, reason advances from one item to another distinct in the mental order, as when we proceed according to intrinsic causes, by synthesis when we go from the most universal forms to the more particular ones, by analysis when we proceed conversely, because what is more universal is more simple. Now that which is most universal is common to all beings; and so the ultimate end of analysis in this process is the consideration of being and the properties of being as being. And, as we said above, these are the objects of divine science; namely, the separate substances and that which is common to all beings. It is evident, therefore, that its thinking is supremely intellectual.

It also follows that divine science gives principles to all the other sciences, because intellectual thinking is the starting point of rational thinking; and for this reason it is called first philosophy. Nevertheless it is learned after physics and the other sciences, because intellectual thinking is the terminus of rational thinking. For this reason it is called metaphysics, as if to say beyond physics, for in the process of analysis it comes after physics.

Replies to Opposing Arguments:

Reply to 1. We say that divine science proceeds intellectually not as though it makes no use of reason, moving forward from principles to conclusions, but because its reasoning most closely approaches intellectual consideration and its conclusions are closest to its principles.

Reply to 2. God is beyond the comprehension of every created intellect, but he is not beyond the uncreated intellect, since in knowing himself he comprehends himself. However, he is above the intellect of everyone here on earth as regards knowing what he is, but not as regards knowing that he is, The blessed in heaven, however, also know what he is, because they see his essence. Nevertheless divine science is not only about God. It is concerned with other things as well, which are not beyond the human intellect even in its present state as regards knowing what they are.

Reply to 3. As we said above, human thought at its terminus in a way approaches angelic knowledge; not that it equals it, but bears a resemblance to it. So Dionysius says: “Souls, by reducing multitude to unity, are rightly considered the equal of the angelic intelligences, as far as this is proper and possible to souls.

Reply to 4. The knowledge of faith also belongs in a special way to understanding (intellectus). For we do not possess the things of faith through the investigation of reason, but we hold them by simply receiving understanding. But we are said not to understand them because the intellect does not have a full knowledge of them. That indeed is promised to us as our reward.


Should We Entirely Abandon the Imagination in Divine Science?

We proceed as follows to the second article:

lt seems that in divine science we must turn to images, for:

1. Divine science was never more appropriately taught than in Sacred Scripture. But treating of the divine in Sacred Scripture we resort to images when divine things are described for us under sensible figures. Therefore in divine science we must turn to images.

2. Again, we grasp divine things only by the intellect; and this is why, as we have said, we must proceed intellectually when treating of them. But, as the Philosopher says, it is impossible to understand without the imagination. Therefore in divine science we must resort to images.

3. Again, we know the divine especially through divine illumination. But as Dionysius says, “It is impossible for the divine light to illumine us from above unless it be hidden within the covering of many sacred veils.” And he calls these sacred veils “images of sensible things.” So in divine science we must turn to images.

4. Again. when dealing with what is sensible we must make use of the imagination. But we know divine things from sensible effects, according to the statement of the Epistle to the Romans: “The invisible things of God... are clearly seen, being understood by the things that are made.” Therefore in divine science we must resort to images.

5. Again, in cognitive matters we are guided especially by the starting point of knowledge; for instance in the sciences of nature we are guided by the senses, from which our knowledge begins. Now in us intellectual knowledge begins in the imagination, since images are related to our intellect as colors to sight, as the De Anima says. Therefore in divine science we must go to the imagination.

6. Again, since the intellect does not use a bodily organ, an injury to such an organ hinders the action of the intellect only insofar as it turns to the imagination. Now the intellect is hindered in its consideration of divine things through an injury of a bodily organ, namely the brain. Therefore in considering divine things the intellect resorts to the imagination.

On the contrary, Dionysius says in his Mystical Theology, speaking to Timothy: “O beloved Timothy, in mystic contemplation abandon the senses.” But the imagination has to do only with the sensible, for it is a movement produced by the sense in act, as the De Anima says. Therefore, since the considerations of divine things are eminently mystical, we should not have recourse to images in them.

Moreover, in the procedure of any science we should avoid what leads to error in it. But, as Augustine says, the principal error regarding divine things is the mistake of those who try transfer to them what they know of the corporeal world. Therefore, since the imagination has to do only with the corporeal, it seems that in divine science we should not go to images.

Moreover, as is clear from Boethius, a lower power does not extend to that which is proper to a higher power. But it belongs to an intellect and to an intelligence to know the divine and the spiritual, as is sid in the De Spiritu et Anima. Therefore, since, as is said in the same work, imagination is below intelligence and intellect, it seems that in the domain of the divine and the spiritual we should no go to the imagination.

Reply: In all knowledge two factors must be taken into account: the beginning and the end. Knowledge begins with apprehension but it ends with judgment, for it is there that knowledge is completed.

Now all our knowledge begins in the senses; from sense perception results the apprehension of the imagination (which is a movement arising from sensory knowledge, as the Philosopher says), and from it in turn springs our intellectual apprehension, for images are like objects to the intellectual soul, as is clear in the De Anima.

But knowledge does not always terminate in the same way. Sometimes it terminates in the senses, sometimes in the imagination, and sometimes in the intellect alone. In some cases the properties and accidents of a thing disclosed by the senses adequately reveal its nature, and then the intellect’s judgment of that nature must conform to what the senses reveal about it. All natural things, which are bound up with sensible matter, are of this kind. So the terminus of knowledge in natural science must be in the senses, with the result that we judge of natural beings as the senses manifest them, as is evident in the De Caelo et Mundo. Accordingly, the man who neglects the senses when dealing with natural things falls into error. By natural things I mean those that are bound up with sensible matter and motion both in existence and in thought.

Our judgment about some things, however, does not depend upon what the sense perceives, because even though they exist in sensible matter they abstract from it when their essences are defined, and we judge of anything chiefly according to the definition of its essence. But because they do not abstract from every kind of matter when their essences are defined but only from sensible matter, and because an object for the imagination remains after sensible characteristics have been set aside, we must judge about such things according to what the imagination reveals. Now the objects of mathematics are of this kind. Accordingly, the knowledge we have through judgment in mathematics must terminate in the imagination and not in the senses, because mathematical judgment goes beyond sensory perception. Thus, the judgment about a mathematical line is not always the same as that about a sensible line. For example, that a straight line touches a sphere at only one point is true of an abstract straight line but not of a straight line in matter, as is said in the De Anima.

There are other beings, however, that transcend both that which falls under the senses and that which falls under the imagination; namely, those that are entirely independent of matter both with respect to their being and with respect to their being understood. So, when we know things of this kind through judgment, our knowledge must terminate neither in the imagination nor in the senses.

Nevertheless we reach some knowledge of them through the objects of the senses and the imagination, either by way of causality (as when from an effect we come to know its cause, which is not proportionate to the effect but transcends it), or by way of transcendence, or by way of negation (as when we separate from such beings whatever the sense or imagination apprehends). These are the means of knowing divine things from the sensible world proposed by Dionysius in his Divine Names.

It follows that we can use the senses and the imagination (+) as the starting points but not (~) as the termini of our knowledge of divine things, so that we judge them to be the sort of objects the sense or the imagination apprehends. Now to go to something is to terminate at it. Therefore, we should go neither to the imagination nor to the senses in divine science, to the imagination and not to the senses in mathematics, and to the senses in the natural sciences. For this reason they aree in error who try to proceed in the same way in these three parts of speculative science.

Replies to Opposing Arguments:

Reply to 1. Sacred Scripture does not present divine things to us under sensible images so that our intellect may stop with them, but that it may rise from them to the immaterial world. Thus, as Dionysius says, it even teaches the divine through symbols of base objects in order to offer less occasion of stopping with them.

Reply to 2. The operation of our intellect in its present state is never without an image as regards the beginning of knowledge. But our knowledge need not always terminate at images, so that, in other words, we judge the objects of our understanding to be of the same kind as the objects of the imagination.

Reply to 3. The text of Dionysius refers to the beginning of knowledge and not to its end, which is reached when we know divine things from their sensible effects by the three methods described above; but not in such a way that we must form our judgment of the divine according to the manner of being of these sensible effects.

Reply to 4. That argument is valid when the starting point of knowledge adequately leads to the object we seek to know. This is the way the senses are the starting point in the natural sciences, but not, as we have said, in divine science.

Reply to 5. An image is the starting point of our knowledge, for it is that from which the operation of the intellect begins; not that it passes away, but it remains as the foundation of intellectual activity, just as the principles of demonstration must remain throughout the whole process of science. This is because images are related to the intellect as objects in which it sees whatever it sees, either through a perfect representation or through a negation. Consequently, when our knowledge of images is impeded, we must be completely incapable of knowing anything with our intellect even about divine things. Clearly, we cannot know that God causes bodies, or transcends all bodies, or is not a body, if we do not form an image of bodies; but our judgment of what is divine is not made according to the imagination. Consequently, even though in our present state of life the imagination is necessary in all our knowledge of the divine, with regard to such matters we must never terminate in it.


Can Our Intellect Behold the Divine Form Itself?

We proceed as follows to the third article:

It seems that we are unable to behold the divine form itself, at least in this life, for:

1. As Dionysius says, “If anyone seeing God understood what he saw, he did not see God himself but one of his creations.” Now the divine form is God himself. Therefore we are not able to behold the divine form itself.

2. Again, the divine form is the divine essence itself. Now no one in the present life can see God through his essence. Therefore neither can he behold the divine form.

3. Again, if we see the form of something, we have some knowledge of that thing. But according to Dionysius, our intellect is most united to God when it knows absolutely nothing of him. Therefore we are unable to behold the divine form.

4. Again, as was said above, all our knowledge begins from the senses. But what we perceive by the senses is inadequate to reveal the divine form or even the other separate substances. Therefore we are unable to behold the divine form itself.

5. Again, according to the Philosopher, our intellect is related to what is most evident as the eye of an owl to the sun. But the eye of an owl cannot see the sun at all. Therefore neither can our intellect see the divine form itself or other separate forms, which are nature’s most evident beings.

On the contrary, the Apostle says in the Epistle to the Romans: “The invisible things of God are clearly seen by a creature of the world” (that is, by man), “...his eternal power also and divinity.” Now the divine form is simply the divinity itself. Therefore in some way we can know the divine form with our intellect.

Moreover, commenting on the text of Genesis, “I have seen God face to face,” the gloss of Gregory says, “Unless a person somehow beheld it” (namely, divine truth), “he would not feel himself incapable of beholding it.” But we feel that we cannot perfectly see the divine essence. Therefore in some way we do behold it.

Moreover, Dionysius says that “the human mind gradually becomes accustomed to rise from the world of sense to heights beyond this world,” which are nothing else than the separate forms. Therefore we can somehow know the separate forms.

Reply: We know a thing in two ways: in one way when we know that it is, and in another way when we know what it is. Now in order to know what anything is, our intellect must penetrate its quiddity or essence either directly or by means of other things that adequately reveal its quiddity. But in this life our intellect cannot directly penetrate the essence of God or other separate essences, because it directly extends to images, to which it bears the same relation as sight does to color, as the De Anima says. So the intellect can directly conceive the quiddity of a sensible reality but not of an intelligible reality. Thus Dionysius says, “According to our way of knowing, we cannot immediately attain to the contemplation of the invisible.” There are some invisible things, however, whose quiddity or nature is perfectly revealed by the known quiddities of sensible things; and we can also know what these intelligible objects are, although indirectly. For instance, from the fact that we know what man and animal are, we come to know adequately the relation of one to the other, and from this we know what a genus and a species are.

But the sensible natures known to us do not adequately reveal the divine essence or even other separate essences, since naturally considered they do not belong to one genus; and quiddity and all such terms predicated almost equivocally of sensible things and of these substances. That is why Dionysius calls the likenesses of sensible things, transferred to immaterial substances, “unlike likenesses, which intellectual beings participate in one way and sensible beings in another.” Consequently, we cannot have adequate knowledge of the former from the latter by way of likeness or even by way of causality, because the effects of those substances found in lower beings do not measure up to their powers so that we can come to know the essence of their cause in this way.

Accordingly, in the present life it is absolutely impossible to know the essence of immaterial substances, not only (~) by natural knowledge but also (~) by revelation; for, as Dionysius say, the light of divine revelation comes to us adapted to our condition. Thus even though revelation elevates us to know something of which we should otherwise be ignorant, it does not elevate us to know in any other way than through sensible things. Thus Dionysius says: “It is impossible for the divine light to illumine us from above unless it be hidden within the covering of many sacred veils.” Now knowledge by way of the sensible is inadequate to enable us to know the essences of immaterial substances. So we conclude that we do not know what immaterial forms are, but only that they are, whether by natural reason based upon created effects or even by revelation, by means of likenesses taken from sensible things.

It should be noticed, however, that we cannot know that a thing is without knowing in some way what it is, either perfectly or at least confusedly, as the Philosopher says we know things defined before we know the parts of their definition. For if a person knows that man exists and wants to find out what man is by definition, he must know the meaning of the term “man.” And this is possible only if he somehow forms a concept of what he knows to exist, even though he does not know its definition. That is to say, he forms a concept of man by knowing a proximate or remote genus and accidental characteristics which reveal him externally. For our knowledge of definitions, like that of demonstrations, must begin with some previous knowledge.

Similarly, therefore, we cannot know that God and other immaterial substances exist unless we know somehow, in some confused way, what they are. (~) Now we cannot do this by knowing a proximate or remote genus, for God is in no genus, since his essence is not distinct from his being; a condition required in all genera, as Avicenna says. Created immaterial substances, however, are indeed in a genus; but even though from the viewpoint of logic they share the same remote genus of substance with sensible substances, from the viewpoint of physics they do not belong to the same genus, as neither do heavenly and terrestrial bodies. For the corruptible and the incorruptible do not belong to the same genus, as the Metaphysics says. For the logician considers concepts in themselves; and from this point of view nothing prevents the immaterial and the material, or the incorruptible and the corruptible, from having something in common. But the philosopher of nature and the metaphysician treat of essences as existing in reality; and therefore they say that there are different genera wherever they find diverse modes of potency and act, and consequently diverse modes of being. Neither has God any accidental characteristics, as we will prove later. If other immaterial substances have such characteristics, we do not know them. Accordingly, we cannot say that we know immaterial substances obscurely by knowing their genus and observable accidents.

Instead of knowing the genus of these substances, we know them (+) by negations; for example, by understanding that they are immaterial, incorporeal, without shapes, and so on. The more negations we know of them the less vaguely we understand them, for subsequent negations limit and determine a previous negation as differences do a remote genus. Our knowledge of the heavenly bodies is also negative for the most part, because they belong to a different genus from that of inferior bodies. We know, for instance, that they are not light or heavy, or hot or cold. And instead of accidental characteristics in these substances we have their connections with sensible ones, either with regard to (+) the relationship of cause to effect or with regard to (+) the relationship of transcendence.

We conclude, then, that in the case of immaterial forms we know that they exist; and instead of knowing what they are we have knowledge of them by way of negation, by way of causality, and by way of transcendence. These are the same ways Dionysius proposes in his Divine Names; and this is how Boethius understands that we can know the divine form by removing all images, and not that we know that it is. The solution of the opposing arguments is clear from what has been said: for the first arguments are based on perfect knowledge of what a thing is, the others on imperfect knowledge of the sort described.


Can Our Intellect Behold the Divine Form by Means of Some Speculative Science?

We proceed as follows to the fourth article:

It seems that we can come to behold the divine form through the speculative sciences, for:

1. As Boethius says here, theology is a part of speculative science. But, as he says, it belongs to theology to behold the divine form itself. Therefore we can arrive at a knowledge of that form through the speculative sciences.

2. Again, there is a speculative science treating of immaterial substances, namely divine science. Now any science treating of a substance beholds the form of that substance, because all knowledge is by means of form, and according to the Philosopher all demonstration begins with essence. Therefore we can behold separate forms through the speculative sciences.

3. Again, according to the philosophers, the ultimate happiness of man is to understand the separate substances For, since happiness is the most perfect activity, it must have to do with the most excellent things falling under the intellect, as we can learn from the Philosopher in the Ethics. Now the happiness described by the philosophers is an activity springing from wisdom, since wisdom is the most perfect virtue of the most perfect power ─ the intellect; and, as the Ethics says, this activity is happiness. Through wisdom, therefore, we understand the separate substances. Now wisdom is a speculative science, as is clear in the Metaphysics and Ethics. So we can understand the separate substances through the speculative sciences.

4. Again, if something is unable to reach the end for which it exists it is to no purpose. But the inquiry in all the speculative sciences is directed to a knowledge of the separate substances as to its end, because in any class of things the most perfect is the goal [of all the rest], Therefore if substances of this sort cannot be understood through the speculative sciences, all of them would be to no purpose, which is absurd.

5. Again, everything directed by nature to an end has been previously endowed with principles by which it is able to arrive at that end and by which it also tends toward that end; for the Principles of natural motions are within a thing. Now the end of man to which he is directed by nature is to know the immaterial substances, as both the saints and the philosophers teach. So man is naturally endowed with principles of that knowledge. But everything we can arrive at from naturally known principles is included in one of the speculative sciences. Therefore the knowledge of immaterial substances pertains to some speculative sciences.

On the contrary, the Commentator says that there are two possible consequences of this position. (1) Either the speculative sciences are not yet perfect, because we have not discovered the sciences by which we can know the separate substances, and this owing to the fact we do not yet understand these substances because of our ignorance of some principles; or (2) if it happens because of some defect in our nature that we cannot discover the speculative sciences by which these substances may be known, it follows that, if some men can discover these sciences, we and they are men only in an equivocal sense.

The first of these is improbable; the second is impossible. So we cannot understand these substances through some speculative sciences.

Moreover, in the speculative sciences we search after definitions, by which we understand the essences of things through the division of a genus into differences and through the examination of a thing’s causes and accidents, which contribute a great deal to our knowledge of the essence. But we cannot know these in the case of immaterial substances, because, as we have already said, from the viewpoint of physics they have no (~) genus in common with the sensible substances known to us. And either they do not have a (~) cause, as in the case of God, or their cause is deeply hidden from us, as in the case of the angels, Their (~) accidents are also unknown to us. So there can be no speculative science through which we may come to understand immaterial substances.

Moreover, in the speculative sciences we know the essences of things through definitions. Now a definition is a phrase made up of a genus and differences. But the essences of these substances are simple and there is no composition in their quiddities, as is clear from the Philosopher and the Commentator. So we cannot understand these substances through the speculative sciences.

Reply: In the speculative sciences we always proceed from something previously known, both in demonstrating propositions and also in finding definitions. For just as one comes to know a conclusion by means of propositions previously known, so also from the concept of a genus and difference and from the causes of a thing he comes to know its species. But it is impossible to go on to infinity in this case, because then all science would cease, both as regards demonstrations and as regards definitions, since the infinite cannot be traversed. So inquiry in all the speculative sciences works back to something first given, which one does not have to learn or discover (otherwise he would have to go on to infinity), but which he knows naturally. Such are the indemonstrable principles of demonstration (for example, Every whole is greater than its part, and the like), to which all demonstrations in the sciences are reducible. Such, too, are the first conceptions of the intellect (for example, being, one, and the like), to which all definitions in the sciences must be reduced.

From this it is clear that the only things we can know in the speculative sciences, either through demonstration or definition, are those that lie within the range of these naturally known principles. Now these principles are revealed to man by the light of the agent intellect, which is something natural to him; and this light makes things known to us only to the extent that it renders images actually intelligible; for in this consists the operation of the agent intellect, as the De Anima says. Now images are taken from the senses. So our knowledge of the above-mentioned principles begins in the senses and memory, as is evident from the Philosopher. Consequently, these principles do not carry us beyond that which we can know from the objects grasped by the senses.

Now we cannot know the essence of the separate substances through that which we take from the senses. This is clear from what was said above. But through sensible things we can arrive at a knowledge of the existence of these substances and of some of their characteristics. So we cannot know the quiddity of any separate substance by means of a speculative science, though the speculative sciences enable us to know the existence of these substances and some of their traits; for instance, that they are intellectual, incorruptible, and the like. This is also the teaching of the Commentator. Avempace (Ibn-Bajja) was of the opposite opinion; he thought that the quiddities of sensible things adequately reveal immaterial quiddities; but, as the Commentator says, this is clearly false, because quiddity is predicated of both almost in an equivocal sense.

Replies to Opposing Arguments:

Reply to 1. Boethius does not intend to say that through the science of theology we can contemplate the essence of the divine form itself, but only that is transcends all images.

Reply to 2. Some things are knowable to us through themselves; and in clarifying them the speculative sciences use the definitions of these objects to demonstrate their properties, as in the case of the sciences that demonstrate through causes. Other things are not knowable to us through themselves but through their effects. If the effect is proportionate to its cause, we take the quiddity itself of the effect as our starting point to prove that the cause exists and to investigate its quiddity, from which in turn its properties are demonstrated. But if the effect is not proportionate to its cause, we take the definition of the effect as the starting point to prove only the existence of the cause and some of its properties, while the quiddity of the cause remains unknown. This is what happens in the case of the separate substances.

Reply to 3. Man’s happiness is twofold. One is the imperfect happiness found in this life, of which the Philosopher speaks, and this consists in contemplating the separate substances through the habit of wisdom. But this contemplation is imperfect and such as is possible in our present life, not such that we can know their quiddity. The other is the perfect happiness of heaven, where we will see God himself through his essence and the other separate substances. But this happiness will not come through a speculative science; it will come through the light of glory.

Reply to 4. As we have said, the speculative sciences are directed to an imperfect knowledge of the separate substances.

Reply to 5. We are endowed with principles by which we can prepare for that perfect knowledge of separate substances but not with principles by which to reach it. For even though by his nature man is inclined to his ultimate end, he cannot reach it by nature but only by grace, and this owing to the loftiness of that end.