in order to perform its act of perception.
Whether the Souls of Brute Animals Are Subsistent?
Objection 1: It would seem that the souls of brute animals are subsistent. For man is of the same genus as other animals; and, as we have just shown (A. 2), the soul of man is subsistent.
Therefore the souls of other animals are subsistent.
Obj. 2: Further, the relation of the sensitive faculty to sensible objects is like the relation of the intellectual faculty to intelligible objects. But the intellect, apart from the body, apprehends intelligible objects. Therefore the sensitive faculty, apart from the body, perceives sensible objects. Therefore, since the souls of brute animals are sensitive, it follows that they are subsistent; just as the human intellectual soul is subsistent.
Obj. 3: Further, the soul of brute animals moves the body. But the body is not a mover, but is moved. Therefore the soul of brute animals has an operation apart from the body.
_On the contrary,_ Is what is written in the book De Eccl. Dogm. xvi, xvii: "Man alone we believe to have a subsistent soul: whereas the souls of animals are not subsistent."
_I answer that,_ The ancient philosophers made no distinction between sense and intellect, and referred both to a corporeal principle, as has been said (A. 1). Plato, however, drew a distinction between intellect and sense; yet he referred both to an incorporeal principle, maintaining that sensing, just as understanding, belongs to the soul as such. From this it follows that even the souls of brute animals are subsistent. But Aristotle held that of the operations of the soul, understanding alone is performed without a corporeal organ. On the other hand, sensation and the consequent operations of the sensitive soul are evidently accompanied with change in the body; thus in the act of vision, the pupil of the eye is affected by a reflection of color: and so with the other senses.
Hence it is clear that the sensitive soul has no _per se_ operation of its own, and that every operation of the sensitive soul belongs to the composite. Wherefore we conclude that as the souls of brute animals have no _per se_ operations they are not subsistent. For the operation of anything follows the mode of its being.
Reply Obj. 1: Although man is of the same genus as other animals, he is of a different species. Specific difference is derived from the difference of form; nor does every difference of form necessarily imply a diversity of genus.
Reply Obj. 2: The relation of the sensitive faculty to the sensible object is in one way the same as that of the intellectual faculty to the intelligible object, in so far as each is in potentiality to its object. But in another way their relations differ, inasmuch as the impression of the object on the sense is accompanied with change in the body; so that excessive strength of the sensible corrupts sense; a thing that never occurs in the case of the intellect. For an intellect that understands the highest of intelligible objects is more able afterwards to understand those that are lower. If, however, in the process of intellectual operation the body is weary, this result is accidental, inasmuch as the intellect requires the operation of the sensitive powers in the production of the phantasms.
Reply Obj. 3: Motive power is of two kinds. One, the appetitive power, commands motion. The operation of this power in the sensitive soul is not apart from the body; for anger, joy, and passions of a like nature are accompanied by a change in the body. The other motive power is that which executes motion in adapting the members for obeying the appetite; and the act of this power does not consist in moving, but in being moved. Whence it is clear that to move is not an act of the sensitive soul without the body.
Whether the Soul Is Man?
Objection 1: It would seem that the soul is man. For it is written (2 Cor. 4:16): "Though our outward man is corrupted, yet the inward man is renewed day by day." But that which is within man is the soul.
Therefore the soul is the inward man.
Obj. 2: Further, the human soul is a substance. But it is not a universal substance. Therefore it is a particular substance. Therefore it is a "hypostasis" or a person; and it can only be a human person.
Therefore the soul is man; for a human person is a man.
_On the contrary,_ Augustine (De Civ. Dei xix, 3) commends Varro as holding "that man is not a mere soul, nor a mere body; but both soul and body."
_I answer that,_ The assertion "the soul is man," can be taken in two senses. First, that man is a soul; though this particular man, Socrates, for instance, is not a soul, but composed of soul and body.
I say this, forasmuch as some held that the form alone belongs to the species; while matter is part of the individual, and not the species.
This cannot be true; for to the nature of the species belongs what the definition signifies; and in natural things the definition does not signify the form only, but the form and the matter. Hence in natural things the matter is part of the species; not, indeed, signate matter, which is the principle of individuality; but the common matter. For as it belongs to the notion of this particular man to be composed of this soul, of this flesh, and of these bones; so it belongs to the notion of man to be composed of soul, flesh, and bones; for whatever belongs in common to the substance of all the individuals contained under a given species, must belong to the substance of the species.
It may also be understood in this sense, that this soul is this man; and this could be held if it were supposed that the operation of the sensitive soul were proper to it, apart from the body; because in that case all the operations which are attributed to man would belong to the soul only; and whatever performs the operations proper to a thing, is that thing; wherefore that which performs the operations of a man is man. But it has been shown above (A. 3) that sensation is not the operation of the soul only. Since, then, sensation is an operation of man, but not proper to him, it is clear that man is not a soul only, but something composed of soul and body. Plato, through supposing that sensation was proper to the soul, could maintain man to be a soul making use of the body.
Reply Obj. 1: According to the Philosopher (Ethic. ix, 8), a thing seems to be chiefly what is princip[al] in it; thus what the governor of a state does, the state is said to do. In this way sometimes what is princip[al] in man is said to be man; sometimes, indeed, the intellectual part which, in accordance with truth, is called the "inward" man; and sometimes the sensitive part with the body is called man in the opinion of those whose observation does not go beyond the senses. And this is called the "outward" man.
Reply Obj. 2: Not every particular substance is a hypostasis or a person, but that which has the complete nature of its species. Hence a hand, or a foot, is not called a hypostasis, or a person; nor, likewise, is the soul alone so called, since it is a part of the human species.
Whether the Soul Is Composed of Matter and Form?
Objection 1: It would seem that the soul is composed of matter and form. For potentiality is opposed to actuality. Now, whatsoever things are in actuality participate of the First Act, which is God; by participation of Whom, all things are good, are beings, and are living things, as is clear from the teaching of Dionysius (Div. Nom.
v). Therefore whatsoever things are in potentiality participate of the first potentiality. But the first potentiality is primary matter.
Therefore, since the human soul is, after a manner, in potentiality; which appears from the fact that sometimes a man is potentially understanding; it seems that the human soul must participate of primary matter, as part of itself.
Obj. 2: Further, wherever the properties of matter are found, there matter is. But the properties of matter are found in the soul--namely, to be a subject, and to be changed, for it is a subject to science, and virtue; and it changes from ignorance to knowledge and from vice to virtue. Therefore matter is in the soul.
Obj. 3: Further, things which have no matter, have no cause of their existence, as the Philosopher says _Metaph._ viii (Did. vii, 6). But the soul has a cause of its existence, since it is created by God.
Therefore the soul has matter.
Obj. 4: Further, what has no matter, and is a form only, is a pure act, and is infinite. But this belongs to God alone. Therefore the soul has matter.
_On the contrary,_ Augustine (Gen. ad lit. vii, 7,8,9) proves that the soul was made neither of corporeal matter, nor of spiritual matter.
_I answer that,_ The soul has no matter. We may consider this question in two ways. First, from the notion of a soul in general; for it belongs to the notion of a soul to be the form of a body. Now, either it is a form by virtue of itself, in its entirety, or by virtue of some part of itself. If by virtue of itself in its entirety, then it is impossible that any part of it should be matter, if by matter we understand something purely potential: for a form, as such, is an act; and that which is purely potentiality cannot be part of an act, since potentiality is repugnant to actuality as being opposite thereto. If, however, it be a form by virtue of a part of itself, then we call that part the soul: and that matter, which it actualizes first, we call the "primary animate."
Secondly, we may proceed from the specific notion of the human soul inasmuch as it is intellectual. For it is clear that whatever is received into something is received according to the condition of the recipient. Now a thing is known in as far as its form is in the knower. But the intellectual soul knows a thing in its nature absolutely: for instance, it knows a stone absolutely as a stone; and therefore the form of a stone absolutely, as to its proper formal idea, is in the intellectual soul. Therefore the intellectual soul itself is an absolute form, and not something composed of matter and form. For if the intellectual soul were composed of matter and form, the forms of things would be received into it as individuals, and so it would only know the individual: just as it happens with the sensitive powers which receive forms in a corporeal organ; since matter is the principle by which forms are individualized. It follows, therefore, that the intellectual soul, and every intellectual substance which has knowledge of forms absolutely, is exempt from composition of matter and form.
Reply Obj. 1: The First Act is the universal principle of all acts; because It is infinite, virtually "precontaining all things," as Dionysius says (Div. Nom. v). Wherefore things participate of It not as a part of themselves, but by diffusion of Its processions. Now as potentiality is receptive of act, it must be proportionate to act.
But the acts received which proceed from the First Infinite Act, and are participations thereof, are diverse, so that there cannot be one potentiality which receives all acts, as there is one act, from which all participated acts are derived; for then the receptive potentiality would equal the active potentiality of the First Act.
Now the receptive potentiality in the intellectual soul is other than the receptive potentiality of first matter, as appears from the diversity of the things received by each. For primary matter receives individual forms; whereas the intelligence receives absolute forms.
Hence the existence of such a potentiality in the intellectual soul does not prove that the soul is composed of matter and form.
Reply Obj. 2: To be a subject and to be changed belong to matter by reason of its being in potentiality. As, therefore, the potentiality of the intelligence is one thing and the potentiality of primary matter another, so in each is there a different reason of subjection and change. For the intelligence is subject to knowledge, and is changed from ignorance to knowledge, by reason of its being in potentiality with regard to the intelligible species.
Reply Obj. 3: The form causes matter to be, and so does the agent; wherefore the agent causes matter to be, so far as it actualizes it by transmuting it to the act of a form. A subsistent form, however, does not owe its existence to some formal principle, nor has it a cause transmuting it from potentiality to act. So after the words quoted above, the Philosopher concludes, that in things composed of matter and form "there is no other cause but that which moves from potentiality to act; while whatsoever things have no matter are simply beings at once." [*The Leonine edition has, "simpliciter sunt quod vere entia aliquid." The Parma edition of St. Thomas's Commentary on Aristotle has, "statim per se unum quiddam est...et ens quiddam."]
Reply Obj. 4: Everything participated is compared to the participator as its act. But whatever created form be supposed to subsist "per se," must have existence by participation; for "even life," or anything of that sort, "is a participator of existence," as Dionysius says (Div. Nom. v). Now participated existence is limited by the capacity of the participator; so that God alone, Who is His own existence, is pure act and infinite. But in intellectual substances there is composition of actuality and potentiality, not, indeed, of matter and form, but of form and participated existence. Wherefore some say that they are composed of that "whereby they are" and that "which they are"; for existence itself is that by which a thing is.
Whether the Human Soul Is Incorruptible?
Objection 1: It would seem that the human soul is corruptible. For those things that have a like beginning and process seemingly have a like end. But the beginning, by generation, of men is like that of animals, for they are made from the earth. And the process of life is alike in both; because "all things breathe alike, and man hath nothing more than the beast," as it is written (Eccles. 3:19). Therefore, as the same text concludes, "the death of man and beast is one, and the condition of both is equal." But the souls of brute animals are corruptible. Therefore, also, the human soul is corruptible.
Obj. 2: Further, whatever is out of nothing can return to nothingness; because the end should correspond to the beginning. But as it is written (Wis. 2:2), "We are born of nothing"; which is true, not only of the body, but also of the soul. Therefore, as is concluded in the same passage, "After this we shall be as if we had not been," even as to our soul.
Obj. 3: Further, nothing is without its own proper operation. But the operation proper to the soul, which is to understand through a phantasm, cannot be without the body. For the soul understands nothing without a phantasm; and there is no phantasm without the body as the Philosopher says (De Anima i, 1). Therefore the soul cannot survive the dissolution of the body.
_On the contrary,_ Dionysius says (Div. Nom. iv) that human souls owe to Divine goodness that they are "intellectual," and that they have "an incorruptible substantial life."
_I answer that,_ We must assert that the intellectual principle which we call the human soul is incorruptible. For a thing may be corrupted in two ways--_per se,_ and accidentally. Now it is impossible for any substance to be generated or corrupted accidentally, that is, by the generation or corruption of something else. For generation and corruption belong to a thing, just as existence belongs to it, which is acquired by generation and lost by corruption. Therefore, whatever has existence _per se_ cannot be generated or corrupted except "per se"; while things which do not subsist, such as accidents and material forms, acquire existence or lose it through the generation or corruption of composite things. Now it was shown above (AA. 2, 3) that the souls of brutes are not self-subsistent, whereas the human soul is; so that the souls of brutes are corrupted, when their bodies are corrupted; while the human soul could not be corrupted unless it were corrupted _per se._ This, indeed, is impossible, not only as regards the human soul, but also as regards anything subsistent that is a form alone. For it is clear that what belongs to a thing by virtue of itself is inseparable from it; but existence belongs to a form, which is an act, by virtue of itself. Wherefore matter acquires actual existence as it acquires the form; while it is corrupted so far as the form is separated from it. But it is impossible for a form to be separated from itself; and therefore it is impossible for a subsistent form to cease to exist.
Granted even that the soul is composed of matter and form, as some pretend, we should nevertheless have to maintain that it is incorruptible. For corruption is found only where there is contrariety; since generation and corruption are from contraries and into contraries. Wherefore the heavenly bodies, since they have no matter subject to contrariety, are incorruptible. Now there can be no contrariety in the intellectual soul; for it receives according to the manner of its existence, and those things which it receives are without contrariety; for the notions even of contraries are not themselves contrary, since contraries belong to the same knowledge.
Therefore it is impossible for the intellectual soul to be corruptible. Moreover we may take a sign of this from the fact that everything naturally aspires to existence after its own manner. Now, in things that have knowledge, desire ensues upon knowledge. The senses indeed do not know existence, except under the conditions of "here" and "now," whereas the intellect apprehends existence absolutely, and for all time; so that everything that has an intellect naturally desires always to exist. But a natural desire cannot be in vain. Therefore every intellectual substance is incorruptible.
Reply Obj. 1: Solomon reasons thus in the person of the foolish, as expressed in the words of Wisdom 2. Therefore the saying that man and animals have a like beginning in generation is true of the body; for all animals alike are made of earth. But it is not true of the soul.
For the souls of brutes are produced by some power of the body; whereas the human soul is produced by God. To signify this it is written as to other animals: "Let the earth bring forth the living soul" (Gen. 1:24): while of man it is written (Gen. 2:7) that "He breathed into his face the breath of life." And so in the last chapter of Ecclesiastes (12:7) it is concluded: "(Before) the dust return into its earth from whence it was; and the spirit return to God Who gave it." Again the process of life is alike as to the body, concerning which it is written (Eccles. 3:19): "All things breathe alike," and (Wis. 2:2), "The breath in our nostrils is smoke." But the process is not alike of the soul; for man is intelligent, whereas animals are not. Hence it is false to say: "Man has nothing more than beasts." Thus death comes to both alike as to the body, by not as to the soul.
Reply Obj. 2: As a thing can be created by reason, not of a passive potentiality, but only of the active potentiality of the Creator, Who can produce something out of nothing, so when we say that a thing can be reduced to nothing, we do not imply in the creature a potentiality to non-existence, but in the Creator the power of ceasing to sustain existence. But a thing is said to be corruptible because there is in it a potentiality to non-existence.
Reply Obj. 3: To understand through a phantasm is the proper operation of the soul by virtue of its union with the body. After separation from the body it will have another mode of understanding, similar to other substances separated from bodies, as will appear Whether the Soul Is of the Same Species As an Angel?
Objection 1: It would seem that the soul is of the same species as an angel. For each thing is ordained to its proper end by the nature of its species, whence is derived its inclination for that end. But the end of the soul is the same as that of an angel--namely, eternal happiness. Therefore they are of the same species.
Obj. 2: Further, the ultimate specific difference is the noblest, because it completes the nature of the species. But there is nothing nobler either in an angel or in the soul than their intellectual nature. Therefore the soul and the angel agree in the ultimate specific difference: therefore they belong to the same species.
Obj. 3: Further, it seems that the soul does not differ from an angel except in its union with the body. But as the body is outside the essence of the soul, it seems that it does not belong to its species.
Therefore the soul and angel are of the same species.
_On the contrary,_ Things which have different natural operations are of different species. But the natural operations of the soul and of an angel are different; since, as Dionysius says (Div. Nom. vii), "Angelic minds have simple and blessed intelligence, not gathering their knowledge of Divine things from visible things." Subsequently he says the contrary to this of the soul. Therefore the soul and an angel are not of the same species.
_I answer that,_ Origen (Peri Archon iii, 5) held that human souls and angels are all of the same species; and this because he supposed that in these substances the difference of degree was accidental, as resulting from their free-will: as we have seen above (Q. 47, A. 2).
But this cannot be; for in incorporeal substances there cannot be diversity of number without diversity of species and inequality of nature; because, as they are not composed of matter and form, but are subsistent forms, it is clear that there is necessarily among them a diversity of species. For a separate form cannot be understood otherwise than as one of a single species; thus, supposing a separate whiteness to exist, it could only be one; forasmuch as one whiteness does not differ from another except as in this or that subject. But diversity of species is always accompanied with a diversity of nature; thus in species of colors one is more perfect than another; and the same applies to other species, because differences which divide a genus are contrary to one another. Contraries, however, are compared to one another as the perfect to the imperfect, since the "principle of contrariety is habit, and privation thereof," as is written, _Metaph._ x (Did. ix, 4). The same would follow if the aforesaid substances were composed of matter and form. For if the matter of one be distinct from the matter of another, it follows that either the form is the principle of the distinction of matter--that is to say, that the matter is distinct on account of its relation to divers forms; and even then there would result a difference of species and inequality of nature: or else the matter is the principle of the distinction of forms. But one matter cannot be distinct from another, except by a distinction of quantity, which has no place in these incorporeal substances, such as an angel and the soul. So that it is not possible for the angel and the soul to be of the same species. How it is that there can be many souls of one species will Reply Obj. 1: This argument proceeds from the proximate and natural end. Eternal happiness is the ultimate and supernatural end.
Reply Obj. 2: The ultimate specific difference is the noblest because it is the most determinate, in the same way as actuality is nobler than potentiality. Thus, however, the intellectual faculty is not the noblest, because it is indeterminate and common to many degrees of intellectuality; as the sensible faculty is common to many degrees in the sensible nature. Hence, as all sensible things are not of one species, so neither are all intellectual things of one species.
Reply Obj. 3: The body is not of the essence of the soul; but the soul by the nature of its essence can be united to the body, so that, properly speaking, not the soul alone, but the "composite," is the species. And the very fact that the soul in a certain way requires the body for its operation, proves that the soul is endowed with a grade of intellectuality inferior to that of an angel, who is not united to a body.
QUESTION 76 OF THE UNION OF BODY AND SOUL (In Eight Articles) We now consider the union of the soul with the body; and concerning this there are eight points of inquiry: (1) Whether the intellectual principle is united to the body as its form?
(2) Whether the intellectual principle is multiplied numerically according to the number of bodies; or is there one intelligence for all men?
(3) Whether in the body the form of which is an intellectual principle, there is some other soul?
(4) Whether in the body there is any other substantial form?
(5) Of the qualities required in the body of which the intellectual principle is the form?
(6) Whether it be united to such a body by means of another body?
(7) Whether by means of an accident?
(8) Whether the soul is wholly in each part of the body?
Whether the Intellectual Principle Is United to the Body As Its Form?
Objection 1: It seems that the intellectual principle is not united to the body as its form. For the Philosopher says (De Anima iii, 4) that the intellect is "separate," and that it is not the act of any body.
Therefore it is not united to the body as its form.
Obj. 2: Further, every form is determined according to the nature of the matter of which it is the form; otherwise no proportion would be required between matter and form. Therefore if the intellect were united to the body as its form, since every body has a determinate nature, it would follow that the intellect has a determinate nature; and thus, it would not be capable of knowing all things, as is clear from what has been said (Q. 75, A. 2); which is contrary to the nature of the intellect. Therefore the intellect is not united to the body as its form.
Obj. 3: Further, whatever receptive power is an act of a body, receives a form materially and individually; for what is received must be received according to the condition of the receiver. But the form of the thing understood is not received into the intellect materially and individually, but rather immaterially and universally: otherwise the intellect would not be capable of the knowledge of immaterial and universal objects, but only of individuals, like the senses. Therefore the intellect is not united to the body as its form.
Obj. 4: Further, power and action have the same subject; for the same subject is what can, and does, act. But the intellectual action is not the action of a body, as appears from above (Q. 75, A. 2).
Therefore neither is the intellectual faculty a power of the body.
But virtue or power cannot be more abstract or more simple than the essence from which the faculty or power is derived. Therefore neither is the substance of the intellect the form of a body.
Obj. 5: Further, whatever has _per se_ existence is not united to the body as its form; because a form is that by which a thing exists: so that the very existence of a form does not belong to the form by itself. But the intellectual principle has _per se_ existence and is subsistent, as was said above (Q. 75, A. 2). Therefore it is not united to the body as its form.
Obj. 6: Further, whatever exists in a thing by reason of its nature exists in it always. But to be united to matter belongs to the form by reason of its nature; because form is the act of matter, not by an accidental quality, but by its own essence; otherwise matter and form would not make a thing substantially one, but only accidentally one.
Therefore a form cannot be without its own proper matter. But the intellectual principle, since it is incorruptible, as was shown above (Q. 75, A. 6), remains separate from the body, after the dissolution of the body. Therefore the intellectual principle is not united to the body as its form.
_On the contrary,_ According to the Philosopher, _Metaph._ viii (Did.
vii 2), difference is derived from the form. But the difference which constitutes man is "rational," which is applied to man on account of his intellectual principle. Therefore the intellectual principle is the form of man.
_I answer that,_ We must assert that the intellect which is the principle of intellectual operation is the form of the human body. For that whereby primarily anything acts is a form of the thing to which the act is to be attributed: for instance, that whereby a body is primarily healed is health, and that whereby the soul knows primarily is knowledge; hence health is a form of the body, and knowledge is a form of the soul. The reason is because nothing acts except so far as it is in act; wherefore a thing acts by that whereby it is in act. Now it is clear that the first thing by which the body lives is the soul.
And as life appears through various operations in different degrees of living things, that whereby we primarily perform each of all these vital actions is the soul. For the soul is the primary principle of our nourishment, sensation, and local movement; and likewise of our understanding. Therefore this principle by which we primarily understand, whether it be called the intellect or the intellectual soul, is the form of the body. This is the demonstration used by Aristotle (De Anima ii, 2).
But if anyone says that the intellectual soul is not the form of the body he must first explain how it is that this action of understanding is the action of this particular man; for each one is conscious that it is himself who understands. Now an action may be attributed to anyone in three ways, as is clear from the Philosopher (Phys. v, 1); for a thing is said to move or act, either by virtue of its whole self, for instance, as a physician heals; or by virtue of a part, as a man sees by his eye; or through an accidental quality, as when we say that something that is white builds, because it is accidental to the builder to be white. So when we say that Socrates or Plato understands, it is clear that this is not attributed to him accidentally; since it is ascribed to him as man, which is predicated of him essentially. We must therefore say either that Socrates understands by virtue of his whole self, as Plato maintained, holding that man is an intellectual soul; or that intelligence is a part of Socrates. The first cannot stand, as was shown above (Q. 75, A. 4), for this reason, that it is one and the same man who is conscious both that he understands, and that he senses. But one cannot sense without a body: therefore the body must be some part of man. It follows therefore that the intellect by which Socrates understands is a part of Socrates, so that in some way it is united to the body of Socrates.
The Commentator held that this union is through the intelligible species, as having a double subject, in the possible intellect, and in the phantasms which are in the corporeal organs. Thus through the intelligible species the possible intellect is linked to the body of this or that particular man. But this link or union does not sufficiently explain the fact, that the act of the intellect is the act of Socrates. This can be clearly seen from comparison with the sensitive faculty, from which Aristotle proceeds to consider things relating to the intellect. For the relation of phantasms to the intellect is like the relation of colors to the sense of sight, as he says _De Anima_ iii, 5,7. Therefore, as the species of colors are in the sight, so are the species of phantasms in the possible intellect.
Now it is clear that because the colors, the images of which are in the sight, are on a wall, the action of seeing is not attributed to the wall: for we do not say that the wall sees, but rather that it is seen. Therefore, from the fact that the species of phantasms are in the possible intellect, it does not follow that Socrates, in whom are the phantasms, understands, but that he or his phantasms are understood.
Some, however, tried to maintain that the intellect is united to the body as its motor; and hence that the intellect and body form one thing so that the act of the intellect could be attributed to the whole. This is, however, absurd for many reasons. First, because the intellect does not move the body except through the appetite, the movement of which presupposes the operation of the intellect. The reason therefore why Socrates understands is not because he is moved by his intellect, but rather, contrariwise, he is moved by his intellect because he understands. Secondly, because since Socrates is an individual in a nature of one essence composed of matter and form, if the intellect be not the form, it follows that it must be outside the essence, and then the intellect is the whole Socrates as a motor to the thing moved. Whereas the act of intellect remains in the agent, and does not pass into something else, as does the action of heating.
Therefore the action of understanding cannot be attributed to Socrates for the reason that he is moved by his intellect. Thirdly, because the action of a motor is never attributed to the thing moved, except as to an instrument; as the action of a carpenter to a saw. Therefore if understanding is attributed to Socrates, as the action of what moves him, it follows that it is attributed to him as to an instrument. This is contrary to the teaching of the Philosopher, who holds that understanding is not possible through a corporeal instrument (De Anima iii, 4). Fourthly, because, although the action of a part be attributed to the whole, as the action of the eye is attributed to a man; yet it is never attributed to another part, except perhaps indirectly; for we do not say that the hand sees because the eye sees.
Therefore if the intellect and Socrates are united in the above manner, the action of the intellect cannot be attributed to Socrates.
If, however, Socrates be a whole composed of a union of the intellect with whatever else belongs to Socrates, and still the intellect be united to those other things only as a motor, it follows that Socrates is not one absolutely, and consequently neither a being absolutely, for a thing is a being according as it is one.
There remains, therefore, no other explanation than that given by Aristotle--namely, that this particular man understands, because the intellectual principle is his form. Thus from the very operation of the intellect it is made clear that the intellectual principle is united to the body as its form.
The same can be clearly shown from the nature of the human species.
For the nature of each thing is shown by its operation. Now the proper operation of man as man is to understand; because he thereby surpasses all other animals. Whence Aristotle concludes (Ethic. x, 7) that the ultimate happiness of man must consist in this operation as properly