Having considered spiritual and also corporeal creatures, we should now consider human beings, who are composed of a spiritual and corporeal nature. And first we should consider the nature of human beings [QQ75-89], then second their production [QQ90-102].
Now it is the theologian's role to consider the nature of human beings with reference to the soul, not with reference to the body ── except in light of the relationship that the body has to the soul. And so our first consideration will be turned toward soul. And because, as Dionysius says in Celestial Hierarchy 11.2, three things are found in spiritual substances ── essence, power, and operation ── we will consider
· first, what pertains to the soul's essence [QQ75-76];
· second, what pertains to its power or capacities [QQ77-83];
· third, what pertains to its operation [QQ84-89].
Under the first heading, two kinds of considerations arise:
· first, concerning the soul itself in its own right [Q75];
· second, concerning its union with body [Q76].
Regarding the first of these, there are seven questions.
a1. Is the soul a body?
a2. Is the human soul something subsistent?
a3. Are the souls of brute animals subsistent?
a4. Is the soul the human being, or is the human being rather something composed of soul and body?
a5. Is the soul composed of matter and form?
a6. Is the human soul incorruptible?
a7. Does the soul belong to the same species as an angel?
Article 1. Is the soul a body?
It seems that the soul is a body:
1. The soul is what moves the body. But it does not produce motion without itself being in motion: first, because it seems nothing can produce motion unless it is in motion, for the reason that nothing gives to another that which it does not have. (For example: that which is not hot does not produce heat.) Also, if something produces motion without being in motion, then that causes a motion that lasts forever and continues in the same way, as is proved in Physics VIII [259b32-260a5]. We don't see this in the motion of animals, which comes from the soul. Therefore the soul produces motion and is in motion. But every such thing is a body. Therefore the soul is a body.
2. All cognition is brought about through some likeness. But there can be no likeness between a body and a nonbodily thing. Therefore if the soul were not a body, it could have no cognition of bodily things.
3. There must be some contact between mover and moved. But contact occurs only between bodies. Therefore since the soul moves the body, it seems that the soul is a body.
On the contrary. Augustine says in De trinitate VI [vi.8] that the soul is said to be simple relative to the body "because it is not spread out in bulk over the space of some area."
Reply. In order to investigate the soul's nature one must start by pointing out that the soul (anima) is said to be the first principle of life in the things that are alive around us. For we say that living things are animate, whereas inanimate things are those without life. Now life is displayed above all by two functions: cognition and movement. But the ancient philosophers, unable to transcend their imaginations, claimed that the principle behind these functions is a body. They said that the only things that exist are bodies, and that what is not a body is nothing. And, in keeping with this doctrine, they said that the soul is a body.
Now although there are many ways in which this view can be shown to be false, we are going to employ one argument by which it is clear in a quite general and certain way that the soul is not a body. It is clear, first, that not just any principle of an operation associated with life is a soul. For if so then the eye would be a soul, since it is a principle of seeing, and the same would have to be said for the soul's other instruments. But we say that the first principle of life is the soul. Now although a body could be a principle of life, in the way that the heart is a principle of life in an animal, nevertheless no body can be the first principle of life. For it is clear that to be a principle of life, or to be living, does not hold of a body as the result of its being a body: otherwise every body would be living, or a principle of life. Therefore it holds of some body that it is living, or that it is even a principle of life, through its being such a body. But as for the fact that it is actually such, it has this from a principle that is called its actuality. Therefore the soul, which is the first principle of life, is not a body but the actuality of a body. And this is so in just the way that heat, which is the principle of heating, is not a body, but a certain actuality of a body.
Ad 1. Since everything that is in motion is in motion due to another, and this cannot continue on into infinity, it is necessary to say that not every mover is in motion. For since to be in motion is to pass from potentiality to actuality, that which produces the motion gives what it has to the thing in motion, insofar as it actualizes that thing. But, as Aristotle shows in Physics VIII [ch. 6], there is one mover that is completely immobile ── in motion neither per se nor per accidens ── and such a mover can produce a motion that is always uniform. There is another mover that is not in motion per se, but is in motion per accidens, and for that reason it does not produce a motion that is always uniform. The soul is such a mover. There is still another mover that is in motion per se ── the body. And because the ancient natural philosophers believed that nothing but bodies existed, they claimed that everything producing motion is in motion, that the soul is in motion per se, and that it is a body.
Ad 2. It is not necessary for a likeness of the thing cognized to exist actually in the nature of the thing that cognizes. But if there is something that is at first potentially cognizing and then later actually doing so, the likeness of the thing being cognized must be in the nature of the thing cognizing not actually, but only potentially. (In this way, color is in the pupil not actually, but only potentially.) Hence there is no need for the likeness of bodily things to exist actually in the soul's nature; instead, that nature must be in potentiality for likenesses of this sort. But because the ancient natural philosophers did not know to distinguish between actuality and potentiality, they claimed that the soul is a body, so that it could cognize bodies. And, so that it could cognize all bodies, they claimed that it was composed out of the basic principles of all bodies.
Ad 3. There are two kinds of contact: that of quantity and that of power. In the first way, only a body touches a body. In the second way, a body can be touched by something nonbodily that moves the body.
Article 2. Is the human soul something subsistent?
It seems that the human soul is not something subsistent:
1. That which is subsistent is said to be a particular thing (hoc aliquid). It is not the soul that is a particular thing, however, but rather the composite of soul and body. Therefore the soul is not something subsistent.
2. Everything that is subsistent can be said to engage in some operation. But the soul is not said to do so, because (as is said in De anima I [408b11-13]) to say that the soul senses or thinks "is like someone's saying that it weaves or builds." Therefore the soul is not something subsistent.
3. If the soul were something subsistent, then some operation would belong to it without the body. But no operation does belong to it without the body, not even understanding, because it is not possible to understand without a phantasm, and there are no phantasms without the body. Therefore the human soul is not something subsistent.
On the contrary. Augustine says in De trinitate X [vii.10] that "whoever sees that it is the nature of mind both to be a substance and not to be bodily, sees that those who take it to be bodily go wrong because they associate mind with the things that they depend on for conceiving of any nature" ── namely, images of bodies. Therefore the nature of the human mind is not only nonbodily, but also a substance ── that is, something subsistent.
Reply. It is necessary to say that the principle of intellectual operation, which we call the soul of a human being, is a nonbodily and subsistent principle. For it is clear that through the intellect a human being can cognize the natures of all bodies. But that which can cognize certain things must have none of those things in its own nature, because that which exists in it naturally would impede its cognition of other things. In this way we see that a sick person's tongue, infected with a jaundiced and bitter humor, cannot perceive anything sweet; rather, all things seem bitter to that person. Therefore if the intellectual principle were to contain within itself the nature of any body, it could not cognize all bodies. But every body has some determinate nature. Therefore it is impossible for the intellectual principle to be a body.
It is likewise impossible for it to operate through a bodily organ, because the determinate nature even of that bodily organ would prevent the cognition of all bodies. Analogously, a determinate color not just in the pupil, but even in a glass vase, makes liquid poured into that vase seem to be of the same color.
Therefore this intellectual principle, which is called mind or intellect, has an operation on its own (per se) that the body does not share in. But nothing can operate on its own unless it subsists on its own, because every operation belongs to something actually existent, and so a thing operates in the same manner that it exists. (For this reason we say not that heat heats, but that the thing that is hot does so.) We can conclude, therefore, that the human soul, which is called intellect or mind, is something nonbodily and subsistent.
Ad 1. The phrase `particular thing' can be taken in two ways: first, for anything subsistent; second, for something subsistent and complete within the nature of some species. The first rules out something inhering as an accident or material form; the second additionally rules out the imperfection associated with a part. A hand, then, could be called a particular thing in the first way, but not in the second. So therefore, since the human soul is part of the human species, it can be called a particular thing in the first way ── in the sense of being subsistent ── but not in the second. For in this latter way it is the composite of soul and body that is called a particular thing.
Ad 2. Aristotle says those words not with respect to his own position, but with respect to the view of those that were claiming that to think is to be in motion. (So much is clear from the preceding remarks he makes there [408a34-b11].)
Alternatively, one can reply that a thing's acting on its own holds of that which exists on its own. But a thing can sometimes be said to exist on its own if it does not inhere as an accident or a material form, even if it is a part. Still, a thing is said to be strictly subsistent on its own when it neither inheres in the way just stated nor is a part. In this way one's eye or hand could not be said to subsist on its own, nor consequently to operate on its own. Thus even the operations of the parts are attributed to the whole, through the parts. For we say that human beings see through their eyes and touch through their hands. And this is different from how what is hot heats through heat: for there is no way in which heat makes things hot, strictly speaking. Therefore one can say that the soul thinks, just as the eye sees. But one speaks more strictly in saying that the human being thinks, through the soul.
Ad 3. The body is required for the intellect's action not as the organ through which such an action is carried out, but on account of its object. For a phantasm is related to intellect just as color is to sight. But needing a body in this way does not preclude intellect's being subsistent. Otherwise an animal would not be something subsistent, since it needs external sense objects in order to sense.
Article 3. Are the souls of brute animals subsistent?
It seems that the souls of brute animals are subsistent:
1. A human being shares its genus with other animals. But the human soul is something subsistent, as was just shown [75.2]. Therefore the souls of other animals are also subsistent.
2. The sensory capacity stands to sensible things just as the intellective capacity stands to intelligible things. But the intellect apprehends intelligible things without the body. Therefore the senses also apprehend sensible things without the body. But the souls of brute animals are sensory. Therefore they are subsistent, for the same reason that the intellective human soul is.
3. The soul of a brute animal moves the body. The body, however, does not produce motion, but is instead put into motion. Therefore the soul of a brute animal has an operation without the body.
On the contrary is what is said in On Church Dogma [16-17]: "we believe that only a human being has a substantive soul.... The souls of animals, in contrast, are not substantive."
Reply. The ancient philosophers drew no distinction between sense and intellect, and attributed each to a bodily principle, as we have said. Plato, on the other hand, distinguished between intellect and sense, but he nevertheless attributed each to a nonbodily principle, claiming that sensing, just like thinking, holds of the soul in its own right. And from this it followed that even the souls of brute animals are subsistent.
But Aristotle held that, among the soul's functions, only thinking is carried out without a bodily organ. Sensation, on the other hand, and the resulting operations of the sensory soul, clearly do occur with some transformation to the body: in seeing, for instance, the pupil is transformed by the species of a color, and the same is evident in other cases. And so it is clear that the sensory soul does not have some special operation, on its own; rather, every operation of the sensory soul belongs to the compound. From this it follows that since the souls of brute animals do not operate on their own, they are not subsistent. For as a thing exists, so it operates.
Ad 1. A human being, though sharing a genus with other animals, still differs in species. A difference in species, however, is marked by a difference in form. And not every difference in form must yield a distinction in genus.
Ad 2. In a way it is true that the sensory capacity stands to sensible things just as the intellective capacity stands to intelligible things ── inasmuch as each is in potentiality towards its objects. But in another way they stand differently ── inasmuch as the sensory capacity is affected by something sensible with some transformation to the body. That is why excessive sensible objects harm a sense. This does not occur in the case of intellect, because after it thinks about the most intelligible of things it becomes more able to think about what is less intelligible. And if thinking tires the body, this occurs accidentally, inasmuch as the intellect needs the operation of the sensory powers, through which phantasms are provided to it.
Ad 3. There are two motive powers. One, the appetitive power, commands the motion, and the operation of this power within the sensory soul does not occur without the body. Instead, anger, joy, and all such passions occur with some transformation to the body. The other motive power is what carries out the motion; through it the body's parts are made ready to obey appetite. Its act is not to produce motion but to be put into motion. So it is clear that producing motion is not an act of the sensory soul without the body.
Article 4. Is the soul the human being,
or is the human being rather something
composed of soul and body?
It seems that the soul is the human being:
1. It is said in II Corinthians 4.16 that though he who is our outward human being is corrupted, still he who is inside is renewed day by day. But that which is inside a human being is the soul. Therefore the soul is the inner human being.
2. The human soul is a kind of substance. But it is not a universal substance. Therefore it is a particular substance. Therefore it is a hypostasis, a person. But if so, then it is none other than a human person. Therefore the soul is the human being, since a human person is a human being.
On the contrary. In City of God XIX , Augustine praises Varro, who "held that a human being is neither the soul alone, nor the body alone, but the soul and the body together."
Reply. There are two ways of understanding the claim that the soul is the human being. First, that human being is the soul, but that a particular human being ── Socrates, say ── is not the soul, but a composite of soul and body. I say this because some have claimed that only form belongs to the defining account (ratione) of the species, whereas matter is part of the individual rather than the species. But this cannot be true. For the nature of a species consists in what its definition signifies. But in the case of natural things the definition signifies not the form alone, but the form and the matter. For this reason the matter is part of the species in natural things ── not signate matter, of course, which is the principle of individuation, but common matter. For just as it belongs to the account of this human being to be composed of this soul, this flesh, and these bones, so it belongs to the account of human being to be composed of soul, flesh, and bones. For whatever belongs in common to the substance of all the individuals contained within a species must belong to the substance of the species.
The claim that the soul is the human being can be understood in another way, so that even a particular soul is a particular human being. And this could be maintained, if it were held that the sensory soul's operation belongs to it alone, without the body. For in that case all the operations assigned to a human being would hold of soul alone. But any given thing is identified with what carries out the operations of that thing, and so a human being is identified with what carries out the operations of a human being. We have shown, however, that sensing is not the operation of the soul alone [75.3]. Therefore, since sensing is one of the operations of a human being (even if not one unique to humans), it is clear that a human being is not a soul alone, but something composed of a soul and a body. Plato, however, since he claimed that sensing belongs to the soul alone, could claim that a human being is a soul using its body.
Ad 1. According to the Philosopher in Ethics IX [1168b32], what any thing appears to be, most of all, is that which is foremost in it: a city, for instance, is said to do what the leader of the city does. It is in this way that what is foremost in a human being is sometimes called the human being. Sometimes the intellective part is so called (and truly so); this is spoken of as the inner human being. Sometimes, on the other hand, the sensory part is so called, along with the body (on the view of those who concern themselves solely with sensory things); this is spoken of as the outer human being.
Ad 2. Not every particular substance is a hypostasis or person, but only one that has the complete nature of the species. For this reason a hand or a foot cannot be called a hypostasis or person, and likewise neither can a soul, since the soul is part of the human species.
Article 5. Is the soul composed of matter and form?
It seems that the soul is composed of matter and form:
1. Potentiality is divided against actuality. But each and every thing that is in actuality participates in the first actuality, which is God. It is through participation in him (as Dionysius's teaching in Divine Names [5.5] makes clear) that all things are good, are beings, and are living. Therefore everything that is in potentiality participates in the first potentiality. But the first potentiality is prime matter. Therefore since the human soul is in potentiality in a certain way, as is evident from the fact that a human being is sometimes [only] potentially thinking, it seems that the human soul participates in prime matter as a part of itself.
2. Wherever one finds features distinctive of matter, there one finds matter. But in the soul one does find features distinctive of matter: being a subject, and being changed. For the soul is the subject of knowledge and virtue, and undergoes change from ignorance to knowledge, and from vice to virtue. Therefore there is matter in the soul.
3. Things that do not have matter do not have a cause for their existence, as is said in Metaphysics VIII [1045a36-b7]. But the soul has a cause for its existence, since it is created by God. Therefore the soul has matter.
4. That which does not have matter, but is solely form, is pure and infinite actuality. But this holds only of God. Therefore the soul has matter.
On the contrary. Augustine proves in De Genesi ad litteram VII [vii-ix] that the soul is made neither from corporeal nor from spiritual matter.
Reply. The soul does not have matter, as can be observed in two ways. First, from the defining character (ratione) of soul in general. For it is part of the soul's defining character that it is the form of some body. Therefore it is a form either in respect of its whole or in respect of some part of itself.
C If in respect of its whole, then it is impossible for a part of it to be matter, assuming that matter is said to be solely a potential being. For form, considered as form, is actuality, and that which is solely in potentiality cannot be part of an actuality, since potentiality is incompatible with actuality, being divided against it.
C If it is form in respect of some part of itself, then we will say that that part is the soul. As for the matter it is the actuality of first, we will say that that is what is first ensouled.
Second, our conclusion can be observed in one specific case, from the defining character of the human soul, inasmuch as it is intellective. For it is clear that everything received in something is received in it according to the mode of the recipient. But any given thing is cognized in keeping with how its form exists in the one cognizing. Now the intellective soul cognizes a thing in that thing's unconditioned nature ── for instance, it cognizes a stone as it is a stone, without [material] conditions. Therefore the form of the stone exists in the intellective soul without conditions, in terms of the stone's own formal character. Therefore the intellective soul is an unconditioned form, not something composed of form and matter. For if the intellective soul were composed of matter and form, then the forms of things would be received in it as individuals; then it would cognize only singular things, as happens in the sensory capacities, which receive the forms of things in a corporeal organ. For matter is the principle of individuation for forms. We can conclude, therefore, that the intellective soul ── and every intellectual substance that cognizes forms unconditionally ── lacks composition of form and matter.
Ad 1. The first actuality is the universal principle of all actualities, since it is infinite and virtually "prepossesses all things within itself," as Dionysius says. Thus things participate in it, not as if it is a part [of them], but in virtue of the diffusion of its procession. Now potentiality, since it is receptive of actuality, must be proportioned to actuality. But received actualities, which proceed from the first infinite actuality and are various participations in it, come in different kinds. So there cannot be one potentiality that receives all actualities, in the way that there is one actuality infusing all the participated actualities. (If there were, then that receptive potentiality would be equal to the active potentiality of the first actuality.) The receptive potentiality in the intellective soul, however, is different from the receptive potentiality of prime matter. This is clear from the difference in things being received. For prime matter receives individual forms, whereas the intellect receives unconditioned forms. Hence the existence of such a potentiality in the intellective soul does not show that the soul is composed of matter and form.
Ad 2. Being a subject and being changed hold of matter inasmuch as it is in potentiality. Therefore just as intellect's potentiality is different from prime matter's, so too there is a different account of how it is a subject and how it is changed. For intellect is the subject of knowledge and undergoes change from ignorance to knowledge inasmuch as it is in potentiality for intelligible species.
Ad 3. Form serves as a cause of existence for matter, but so too does an agent. Thus an agent, insofar as it brings matter to the actuality of form by changing it, is a cause of existence for it. But if something is a subsistent form it does not have existence through any formal principle, nor does it have a cause changing it from potentiality to actuality. That is why, after the words cited above, the Philosopher concludes [1045b16-23] that in things that are composed of matter and form, "there is no other cause except that which produces the movement from potentiality to actuality. But those that do not have matter, they are all, without qualification, truly particular beings."
Ad 4. Everything participated in stands as actuality relative to that which participates in it. But any created form that is held to be subsistent per se must participate in existence, since even "life itself," or anything spoken of in this way, "participates in existence itself," as Dionysius says in Divine Names 5.5. But participated existence is limited to the capacity of what participates in it. Hence only God, who is his own existence, is pure and infinite actuality. In the case of intellectual substances, in contrast, there is a composition of actuality and potentiality: not that of matter and form, to be sure, but of form and participated existence. For this reason, some say that these substances are composed of that by which and that which, because existence itself is that by which a thing exists.
Article 6. Is the human soul incorruptible?
It seems that the human soul is corruptible:
1. Things that have a similar starting point and course seem to have a similar end. But human beings and beasts have a similar starting point for their generation, since they are made from earth. There is also a similar course of life in each, since all things breathe alike, and a human being has nothing more than a beast, as is said in Ecclesiastes 3.19. Therefore, as the text there concludes, there is a single death for humans and beasts, and an equal condition for both. But the soul of brute animals is corruptible. Therefore the human soul is also corruptible.
2. Everything that comes from nothing can be turned back into nothing, since the end ought to match the start. But, as is said in Wisdom 2.2, We are born from nothing, which is true not only as regards the body, but also as regards the soul. Therefore, as that passage concludes, After this we will be as if we had not been ── even with regard to soul.
3. Nothing exists without its proper operation. But the soul's proper operation, to understand with phantasms, cannot take place without the body. For, as is said in the De anima, "the soul understands nothing without a phantasm" [431a16-17], and there is no phantasm without the body [403a8-10]. Therefore the soul cannot remain once the body is destroyed.
On the contrary. Dionysius says in Divine Names 4.2 that because of divine goodness human souls are "intellectual" and "have inexhaustible substantial life."
Reply. It is necessary to say that the human soul, which we call the intellective principle, is incorruptible. For there are two ways in which something is corrupted: either per se or per accidens. But it is impossible for something subsistent to be generated or corrupted per accidens ── i.e., by something [else's] being generated or corrupted. For a thing is generated or corrupted in the same way that it exists ── existence being what a thing acquires through generation and loses through corruption. Hence that which has existence per se can be generated or corrupted only per se. Things that do not subsist, on the other hand, such as accidents and material forms, are said to be made and corrupted through the generation and corruption of their composites. But it was shown above that the souls of brute animals are not subsistent [75.3], and that only human souls are [75.2]. So the souls of brute animals are corrupted when their bodies are corrupted, whereas the human soul cannot be corrupted, unless it is corrupted per se. But this, to be sure, is entirely impossible ── not only for it, but for any subsistent thing that is wholly form. For it is clear that what holds of something in its own right is inseparable from it. Existence, however, holds per se of form, which is actuality. As a result, matter acquires actual existence in virtue of its acquiring form, whereas corruption results in virtue of the form's being separated from it. But it is impossible for a form to be separated from itself. As a result, it is impossible for a subsistent form to cease existing.
Further, even if we were to suppose that the soul is composed of matter and form, as some maintain, we would still have to hold that it is incorruptible. For corruption is found only where contrariety is found, since generation and corruption occur from one contrary to another. For that reason celestial bodies, which do not have matter subject to contrariety, are incorruptible. But there cannot be any contrariety in the intellective soul. For it receives in keeping with the mode of its existence, and those things that are received in it are without contrariety. This is because even the concepts of contrary things are not contraries within intellect; instead, the same knowledge embraces contraries. Therefore it is impossible for the intellective soul to be corruptible.
One can also see an indication of this from the fact that each thing naturally desires existence in its own way. Now in the case of things that are cognitive, desire depends on cognition. But the senses cognize only in terms of what is here and now, whereas the intellect apprehends existence unconditionally, according to all times. For this reason everything that has an intellect naturally desires to exist forever. But a natural desire cannot be pointless. Therefore every intellectual substance is incorruptible.
Ad 1. Solomon introduces this argument in the voice of the foolish, as is made clear in Wisdom 2. So the claim that human beings and other animals have a similar starting point for their generation is true as regards the body, since all animals have been made alike from the earth. But the claim is not true as regards the soul. For the soul of brute animals is produced by a bodily power, whereas the human soul is produced by God. And to signify this it is said in Genesis [1.24], as regards the other animals, Let the earth produce the living soul, while as regards human beings it is said [2.7] that He breathed into his face the breath of life. And so the last chapter of Ecclesiastes concludes that Dust reverts to the earth from where it came, and spirit returns to the God who gave it.
Likewise, the course of life is similar as regards the body, and this is what Ecclesiastes 3.19 refers to: All things breathe alike, and also Wisdom 2.2: Smoke and breath are in our nostrils, etc. But as regards the soul the course is not similar, since human beings think and brute animals do not. So it is false to say that a human being has nothing more than a beast. And so there is a similar death as regards the body, but not as regards the soul.
Ad 2. A thing is said to be able to be created not through a passive capacity, but only through the active capacity of a Creator who can produce something from nothing. In just the same way, when it is said that something can be turned back into nothing, the creature is not being credited with the capacity for non-existence; rather, the Creator is being credited with the capacity for not instilling existence. But something is said to be corruptible when the capacity for not existing is present in it.
Ad 3. Understanding with phantasms is the soul's proper operation insofar as it is united to its body. Once separated from its body, however, it will have a different mode of understanding, like that of other substances that are separate from body. This will become clearer below [Q89].
Article 7. Does the soul belong to the same species
as an angel?
It seems that the soul and an angel belong to a single species:
1. Any given thing is directed to its own distinctive end through the nature of its species, through which it has an inclination toward its end. But the soul and an angel have the same end ── namely, eternal blessedness. Therefore they belong to a single species.
2. The ultimate specific differentia is the one that is loftiest, since it fills in the defining character (rationem) of the species. But nothing is loftier in an angel and the soul than intellectual being. Therefore the soul and an angel agree in their ultimate specific differentia. Therefore they belong to a single species.
3. The soul seems to differ from an angel only through its being united to the body. But the body, since it is outside of the soul's essence, does not seem relevant to its species. Therefore the soul and an angel belong to a single species.
On the contrary, things that have distinct natural operations differ in species. But souls and angels have distinct natural operations, because (as Dionysius says in Divine Names 7.2) angelic minds have simple and blessed intellects; they do not accumulate their divine cognition from things that are visible. He later says the opposite of this, regarding the soul. Therefore the soul and an angel do not belong to a single species.
Reply. Origen claimed that all human souls and angels belong to a single species; he supposed this because he claimed that the difference of levels found in such substances was accidental ── stemming (as was said above [47.2c]) from free decision. This cannot be, because incorporeal substances cannot differ numerically unless they differ in species, and unless their natures are unequal. For if they are not composed of matter and form, but are subsistent forms, then it will clearly be necessary for them to differ in species. For the existence of a separated form is intelligible only when there is one form for one species. Likewise, if a separated whiteness existed there could be just one of them: for one whiteness differs from another only through its belonging to one thing or another. Specific difference, however, always implies a concomitant difference in nature, just as among species of colors one color is more perfect than another, and likewise in other cases. The reason for this is that the differentiae that divide up a genus are contraries. Contraries, however, are related in terms of being more and less perfect, because the basis of contrariety is lacking and having, as is said in Metaphysics X [1055a33].
The same conclusion would also follow if substances of this sort were composed of matter and form. For if the matter of one is distinguished from the matter of another, then necessarily either (i) the form is the principle distinguishing the matter (in such a way that matters are different because of a disposition for different forms) and then specific difference and inequality in nature still results; or (ii) matter will be the principle distinguishing the forms. But one matter could be said to be different from another only with respect to quantitative division, which has no place in incorporeal substances like an angel and the soul. Therefore it cannot be the case that an angel and the soul belong to a single species.
As for how there are many souls belonging to a single species, this will be shown below [76.2 ad 1].
Ad 1. That argument holds for an end that is proximate and natural. But eternal blessedness is an end that is ultimate and supernatural.
Ad 2. The ultimate specific differentia is loftiest inasmuch as it is the most determinate ── in the way that actuality is loftier than potentiality. Yet it then follows that intellectual is not the most lofty, because it is indeterminate and common to many levels of intellectuality ── just as sensory is common to many levels of being sensory. So just as not all sensory things belong to a single species, so too neither do all intellectual things.
Ad 3. The body does not belong to the soul's essence, but the soul, due to the nature of its essence, is able to be united to the body. For this reason, it is not the soul that properly belongs to the species, but the compound. And the very fact that the soul in a certain way needs the body for its operation shows that the soul occupies a lower intellectual level than does an angel, which is not united to a body.
Question 76. The Soul's Union with the Body
We should next consider the soul's union with the body. And in this connection there are eight questions.
a1. Is the intellective principle united to the body as its form?
a2. Is the intellective principle numerically multiplied according to the number of bodies? Or is there a single intellect for all human beings?
a3. Does a body whose form is the intellective principle have any other soul?
a4. Is there any other substantial form in such a body?
a5. What sort of body should have the intellective principle as its form?
a6. Is the intellective principle united to such a body through the mediation of any accident?
a7. Is it united to the body through the mediation of any other body?
a8. Is the soul whole in each part of the body?
Article 1. Is the intellective principle
united to the body as its form?
It seems that the intellective principle is not united to the body as its form:
1. The Philosopher says in De anima III that the intellect is separate [429b5], and that it is the actuality of no body [429a24-27]. Therefore it is not united to the body as its form.
2. Every form is determined by the nature of the matter whose form it is; otherwise no proportion would be required between matter and form. Therefore if the intellect were united to the body as its form, then, since every body has a determinate nature, it would follow that the intellect would have a determinate nature. And then it would not be capable of cognizing all things, as is clear from earlier discussions [75.2], which is contrary to the nature of intellect. Therefore the intellect is not united to the body as its form.
3. Any receptive capacity that is the actuality of a body receives a form materially and individually, since the thing received exists in the recipient in keeping with the mode of the recipient. But the form of a thing grasped by intellect is not received in intellect materially and individually, but instead immaterially and universally ── otherwise the intellect would not be capable of cognizing immaterial and universal things, but only singular things, as the senses do. Therefore the intellect is not united to the body as its form.
4. The capacity and the action belong to the same thing, because that which is capable of acting is the same as that which is acting. But intellectual action does not belong to any body, as is clear from earlier discussions [75.2, 75.5]. Therefore neither is the intellective capacity a capacity that belongs to a body. But no power or capacity can be more abstract or simple than the essence from which the power or capacity is derived. Therefore neither is the substance of intellect the form of the body.
5. That which has existence on its own is not united to the body as its form. For a form is that by which a thing exists, and so the existence that belongs to a form does not belong to it in its own right. But the intellective principle has existence in its own right, and it is subsistent, as was said above [75.2]. Therefore it is not united to the body as its form.
6. That which holds of a thing in its own right always holds of it. But it holds of form in its own right to be united with matter, since it is the actuality of matter through its essence, not through any accident. (Otherwise matter and form would make one thing not substantially, but accidentally.) Therefore a form cannot exist without its proper matter. But the intellective principle, since it is incorruptible (as was shown above [75.6]), remains when it is not united to the body, after the body has been corrupted. Therefore the intellective principle is not united to the body as its form.
On the contrary. According to the Philosopher, in Metaphysics VIII [1043a2-21], a differentia is drawn from the form of a thing. But the differentia that gives rise to human being is rational, which is ascribed to a human being on account of the intellective principle. Therefore the intellective principle is the form of a human being.
Reply. It is necessary to say that the intellect, which is the principle of intellectual operation, is the form of the human body. For that through which a thing first operates is a form of that to which the operation is attributed ── e.g., that through which the body is first healed is health; and that through which the soul first knows is knowledge. Thus health is a form of the body, and knowledge a form of the soul. And the reason for this is that nothing acts except insofar as it is in actuality, and therefore it acts through that through which it is in actuality. It is clear, however, that the first thing through which the body lives is the soul. And since life is displayed in different grades of living beings through different operations, the soul is that through which we first carry out any one of these operations of life. For the soul is the first thing through which we are nourished, through which we sense, through which we engage in locomotion, and ── likewise ── through which we first think. Therefore this principle through which we first think, whether it be called intellect or the intellective soul, is the form of the body. And this is Aristotle's demonstration in De anima II [414a4-18].
Now if someone wants to say that the intellective soul is not the form of the body, then it is incumbent on that person to find a way in which the action that is thinking is the action of a particular human being. For each one of us experiences that it is oneself who thinks. Now an action gets attributed to a thing in three ways, as is clear from the Philosopher in Physics V [224a21-34]. For a thing is said to produce movement or to act either
(a) in respect of its whole self, in the way that a doctor heals; or
(b) in respect of a part, in the way that one sees through one's eyes; or
(c) per accidens, in the way that something white is said to build, because the builder accidentally happens to be white.
Therefore when we say that Socrates or Plato thinks, we clearly are not attributing this to him (c) per accidens. For we are attributing it to him inasmuch as he is a human being, which is essentially predicated of him. Therefore either we must say that (c) Socrates thinks in respect of his whole self, as Plato claimed in saying that a human being is the intellective soul; or we must say that (b) the intellect is a part of Socrates. And the first surely cannot be maintained, as was shown above [75.4], because it is the very same human being who perceives himself both to think and to sense. Yet sensing does not occur without the body, and so the body must be a part of the human being. We can conclude, then, that the intellect by which Socrates thinks is a part of Socrates, and consequently the intellect is somehow united to Socrates' body.
The Commentator, in De anima III , says that this union takes place through intelligible species. These species have two subjects, one the possible intellect, the other the phantasms that exist in corporeal organs. In this way, then, the possible intellect is connected to the body of one or another human being though an intelligible species.
But that connection or union is not sufficient for the intellect's action to be Socrates' action. This is clear through a comparison to the senses (which is how Aristotle goes about exploring the characteristics of intellect): for, as is said in De anima III [431a14], phantasms are to intellect just as colors are to sight. Therefore just as the species of colors are in sight, so the species of phantasms are in the possible intellect. But it is evident that we do not attribute the action of sight to a wall just because that wall has the colors whose likenesses are in sight. For we do not say that the wall sees, but rather that it is seen. Therefore just because the species of phantasms are in the possible intellect, it does not follow that Socrates (who has the phantasms) is thinking, but rather that he, or his phantasms, are being thought of.
Now some have wanted to say that the intellect is united to the body as its mover, with the result that from intellect and body one thing comes about, so that the action of intellect can be attributed to the whole. But this is futile for a variety of reasons.
1. The intellect moves the body only through appetite, and appetite's movement presupposes the operation of intellect. Therefore Socrates does not think because he is moved by intellect, but rather the converse: because Socrates thinks, he is accordingly moved by intellect.
2. Because Socrates is an individual in whose nature there is one essence, composed of matter and form, it follows that if the intellect is not his form then it falls outside of his essence. And so the intellect will be related to the whole Socrates as mover is to moved. But thought is an action that stays within the agent; it does not pass into another, as heating does. Therefore thought cannot be attributed to Socrates on account of his being moved by intellect.
3. We attribute a mover's action to the thing being moved only as to an instrument ── e.g., the action of a carpenter, to his saw. Therefore if we attribute thought to Socrates because it is the action of what moves him, then it follows that we are attributing it to him as if to an instrument. This runs contrary to the Philosopher, who holds that thought does not occur through a corporeal instrument.
4. Although we attribute the action of a part to the whole ── e.g., the eye's action to the person ── nevertheless we never attribute that action to a different part (unless perhaps per accidens). For we do not say that the hand sees as a result of the eye's seeing. Therefore if from intellect and Socrates one thing comes about in the proposed way, then the intellect's action cannot be attributed to Socrates. If, on the other hand, Socrates is the whole composed of intellect's union with the rest of Socrates, and nevertheless the intellect is united to the other parts of Socrates only as a mover, then it follows that Socrates is not unconditionally one thing, and consequently that he is not unconditionally a being. For something is a being in just the way that it is one.
The only way that is left, then, is the way that Aristotle proposes: that this particular human being thinks because the intellective principle is his form. In this way, then, from the intellect's very operation, it is evident that the intellective principle is united to the body as its form.
The same can also be made clear from the defining character of the human species. For the nature of a thing is revealed by its operation. But the special operation of a human being, considered as a human being, is to think: for through this we transcend all animals. For this reason, too, Aristotle in the Ethics [1177a12-19] founds our ultimate happiness on this operation ── as on what is special to humans. A human being must obtain its species, then, in accord with the principle of this operation. But everything obtains its species from its own special form. It follows, then, that the intellective principle is the special form of a human being.
It is important to consider, however, that to the extent a form is loftier, to that extent it is more dominant over corporeal matter, less immersed in it, and more surpasses it in its operation or power. For this reason we see that the form of a mixed body has an operation that is not caused by the elemental qualities. And the farther we go in loftiness among forms, the more we find that the power of the form surpasses the elemental matter: the vegetative soul beyond the form of metal, and the sensory soul beyond the vegetative soul. But the human soul is the ultimate in loftiness among forms. Thus its power so surpasses corporeal matter that it has an operation and power that it in no respect shares with corporeal matter. And this power is called the intellect.
It is important to notice, however, that if someone were to claim that the soul is composed of matter and form, then he could in no way say that the soul is the body's form. For since form is actuality, whereas matter is solely potential being, there is no way in which what is composed of matter and form can be the form of something else in respect of its whole. But if it is the form in respect of some part of itself, then we will say that the soul is that which is the form, and we will say that what it is the form of is what is first ensouled ── as was said above [75.5cxx].
Ad 1. As the Philosopher says in Physics II [194b8-15], the last of the natural forms toward which natural philosophy directs its attention ── that is, the human soul ── is indeed separate, but is nevertheless in matter. And he proves this from the fact that "a human being, together with the sun, generates a human being from matter." The human soul is separate, on the one hand, with respect to its intellective power, because its intellective power is not the power of any corporeal organ, in the way that visual power is the actuality of the eye. For thought is an actuality that cannot be exercised through a corporeal organ, in the way that vision is. It is in matter, on the other hand, inasmuch as that soul to which this power belongs is the form of the body, and the end product (terminus) of human generation. So the reason the Philosopher says in De anima III that the intellect is separate is that it is not the power of any corporeal organ.
Ad 2 & 3. Through this the reply to the second and third objections is clear. For in order for a human being to be able to think about all things through intellect, and for the intellect to think about immaterial and universal things, it is enough for the intellective power not to be the actuality of the body.
Ad 4. The human soul, because of its perfection, is not a form that is immersed in corporeal matter or completely subsumed by it. And so there is nothing to stop one of its powers from not being an actuality of the body ── even though the soul is essentially the form of the body.
Ad 5. The soul shares with corporeal matter the existence in which it subsists: from that matter and from the intellective soul, one thing comes about. This occurs in such a way that the existence that belongs to the whole composite also belongs to the soul itself, something that does not occur in the case of other forms, which are not subsistent. And for this reason the human soul continues in its existence after the body is destroyed, whereas other forms do not.
Ad 6. In its own right, the soul is suited to be united to a body, just as a light body is suited, in its own right, to be up high. And just as a light body remains light even after it has been separated from its proper place, and retains its readiness and inclination for that proper place, so the human soul continues in its existence even after it has been separated from its body, and it maintains its natural readiness and inclination for union with its body.
Article 2. Is the intellective principle numerically
multiplied according to the number of bodies?
Or is there a single intellect for all human beings?
It seems that the intellective principle is not multiplied according to the number of bodies, but that there is a single intellect for all human beings:
1. No immaterial substance is multiplied numerically within a single species. But the human soul is an immaterial substance, since (as was shown above [75.5]) it is not composed of matter and form. Therefore there are not multiple human souls within a single species. But all human beings belong to a single species. Therefore all human beings share a single intellect.
2. By removing the cause, one removes the effect. Therefore, if human souls were multiplied according to the number of bodies, it would seem to follow that by taking away the bodies, one would not be left with multiple souls. Instead, out of all those souls, only one thing would be left. This is heretical, because there would then be no difference in rewards and punishments.
3. If my intellect is different from your intellect, then my intellect is something individual, and likewise so is yours. For particulars are things that differ numerically and share in a single species. But everything that is received in something exists in it according to the mode of the recipient. Therefore the species of things would be received individually in my intellect and in yours. This runs contrary to the nature of intellect, which is cognitive of universals.
4. That which is understood exists within the intellect of the one that understands it. Therefore if my intellect is different from yours, there must be one thing understood by me and another by you. As a result that thing will be counted as an individual, and will be understood only potentially, and a common notion will have to be abstracted from both ── since a common intelligible object can be abstracted from any two different things. This runs contrary to the nature of intellect, because in that case the intellect would not seem to be distinct from the imaginative power. Therefore it seems we can conclude that all human beings share a single intellect.
5. When a student acquires knowledge from a teacher, it cannot be said that the teacher's knowledge generates the knowledge in the student, because then knowledge too would be an active form, like heat, which is plainly false. Therefore it seems that numerically the same knowledge that is in the teacher is imparted to the student, which can happen only if each shares in a single intellect. Therefore it seems that the student and the teacher, and consequently all human beings, share in a single intellect.
6. Augustine says in De quantitate animae [32.69] that "if I were to say only that there are many human souls, I would laugh at myself." But it is with respect to intellect most of all that there seems to be a single soul. Therefore all human beings share in a single intellect.
On the contrary. The Philosopher says in Physics II [195b25-28] that just as universal causes are related to universals, so particular causes are related to particulars. But it is impossible for animals that are different in species to share in a soul that is singular in species. Therefore it is impossible for things that are numerically different to share in an intellective soul that is numerically one.
Reply. It is entirely impossible for all human beings to share in a single intellect. This is obviously the case if, as Plato held, human beings are their intellects. For if Socrates and Plato share in just a single intellect, then it would follow that Socrates and Plato are a single human being, and that they are distinguished from one another only through that which is outside the essence of each. Then the distinction between Socrates and Plato would be no different than that between a person wearing a coat and a hat, which is entirely absurd.
It is likewise clear that this is impossible if, in keeping with Aristotle's view, the intellect is held to be a part or capacity of the soul that is a human being's form. For it is impossible that many numerically different things share in a single form ── just as it is impossible that they share in a single existence. The reason is that form is the source of existence.
It is likewise clear that this is impossible no matter how one supposes that the intellect is united to this human being and that one. For it is clear that if there is one principal agent and two instruments, one can speak unconditionally of a single agent, but of several actions. (For instance, if one human being touches different things with each hand, there will one person touching, but two contacts.) If, however, there is a single instrument and different principal agents, then there will be said to be several agents, certainly, but a single action. (For instance, if many people pull a ship with one rope there will be many people pulling, but one act of pulling.) But if there is a single principal agent and a single instrument, we will say that there is a single agent and a single action. (For instance, when a blacksmith strikes with a single hammer there is a single person striking and a single act of striking.)
Yet clearly, no matter how the intellect is either united or joined to this or that human being, the intellect is what is principal among the various things that pertain to a human being. For the sensory powers obey and serve the intellect. Therefore if one were to imagine two human beings possessing distinct intellects but sharing a single sense ── e.g., if two human beings had a single eye ── then there would be more than one person seeing, but a single act of vision. But if there is a single intellect, then no matter how different all the other things are that the intellect uses as instruments, there is no way in which Socrates and Plato could be said to be anything other than a single thinker. And if we add that this thinking, which is the action of intellect, comes about through no other organ than the intellect itself, then it will further follow that there is both a single agent and a single action ── i.e., that all human beings are a single thinker and [have] a single thought (relative to the same object of thought).
Now my intellectual action could be made different from yours through a difference in phantasms ── viz., by there being one phantasm of a stone in me, and another in you ── if that phantasm, as it is one thing in me and another in you, were the form of the possible intellect. For the same agent brings about different actions in virtue of different forms. (The same eye, for instance, has different visions in virtue of the different forms of things.)
But the possible intellect's form is not the phantasm but rather the intelligible species, which is abstracted from phantasms. And a single intellect abstracts only a single intelligible species from different phantasms of the same kind. This is evident in the case of a single human being, in whom there can be different phantasms of stone, though what is abstracted from all of them is a single intelligible species of stone, through which the intellect of a single human being, by a single operation, understands the nature of stone ── despite the difference in phantasms. Therefore if all human beings shared a single intellect, the difference in phantasms in this one and that one could not differentiate the intellectual operation of this human being and that one, as the Commentator supposes in De anima III . We can conclude, therefore, that it is altogether impossible and unacceptable to claim that all human beings share a single intellect.
Ad 1. Although the intellective soul has no matter from which it exists, as angels too do not, nevertheless it is the form of some matter, which is not the case for an angel. And so there are many souls belonging to a single species, corresponding to the divisions in matter. But there absolutely cannot be many angels belonging to a single species.
Ad 2. Any given thing has unity in just the way that it has existence. As a result, judgments about a thing's number are the same as those about its existence. It is clear, however, that the intellectual soul is, as regards its existence, united to the body as its form. Nevertheless, after the body is destroyed, the intellectual soul remains in existence. For the same reason, the number of souls accords with the number of bodies; nevertheless, after the bodies are destroyed, the souls remain in existence, multiplied.
Ad 3. The individuality of what thinks, or of the species through which it thinks, does not exclude its thinking about universals. If it did, then, since separate intellects are a kind of subsistent substance and as a result particular, they could not think about universals. But the materiality of what cognizes, and of the species through which it does so, does impede the cognition of a universal. For just as every action occurs in keeping with the mode of the form through which the agent acts (e.g., heating, in keeping with the mode of heat), so cognition takes place in keeping with the mode of the species by means of which the cognizer cognizes. It is clear, however, that a common nature is distinguished and multiplied by individuating principles that come from matter. Therefore if the form through which cognition comes about is material, and not abstracted from material conditions, then it will be a likeness of the nature of the species or genus inasmuch as it is distinguished and multiplied by individuating principles. The thing's nature, in it commonality, could not in that way be cognized. But if the species is abstracted from the individual conditions of matter, then it will be a likeness of the nature without the things that serve to distinguish and multiply it. In this way the universal will be cognized. And it does not matter, in this regard, whether there is a single intellect or many. For even if there were only one, it would still have to be a certain thing, as would the species through which it thinks.
Ad 4. Regardless of whether there is one or many intellects, that which is understood is one. For that which is understood is in intellect not in its own right, but in respect of its likeness. For, as is said in De anima III [431b29], "it is not the stone that is in the soul, but the species" of the stone. Still, it is the stone that is understood, not the species of the stone, except when intellect reflects on itself. Otherwise, our knowledge would not be about things in the world (de rebus), but about intelligible species.
Still, things that differ in having different forms can be made like the same thing. And because cognition occurs in virtue of the cognizer's being made like the thing being cognized, it follows that the same thing can be cognized by different cognizers. This is plain in the sensory case: for many people see the same color in virtue of different likenesses, and likewise many intellects understand a single intellectual object.
On Aristotle's view, this alone differentiates sense and intellect: that a thing is sensed in keeping with the disposition that it has outside the soul, in its particularity, whereas the nature of the thing that is understood certainly does exist outside the soul, but without having the same mode of existence outside the soul as when it is understood. For what is understood is the common nature, putting to one side the individuating principles; but this is not the mode of existence that it has outside the soul. According to Plato's view, however, the thing understood exists outside the soul according to the same mode in which it is understood. For he held that the natures of things are separated from matter.
Ad 5. The knowledge in the student is different from that in the teacher. As for how it is caused, this will be made clear in what follows [1a 117.1].
Ad 6. Augustine means that it is not only the case that there are many souls ── as if they were not made one in their one specific nature.
Article 3. Does a body whose form is the
intellective principle have any other soul?
It seems that beyond the intellective soul there are other, essentially different souls in a human being ── namely, the sensory and nutritive souls:
1. That which is corruptible and that which is incorruptible do not belong to a single substance. But the intellective soul is incorruptible, whereas the other souls (the sensory and nutritive) are corruptible, as is clear from earlier claims [75.6]. Therefore in a human being the intellective, sensory, and nutritive souls cannot have a single essence.
2. One might reply that the sensory soul in a human being is incorruptible.
On the contrary, the corruptible and the incorruptible differ in genus, as is said in Metaphysics X [1058b26-59a10]. But the sensory soul in a horse, a lion, and other brute animals is corruptible. Therefore if it is incorruptible in a human being, then the sensory soul in humans and in brutes will not belong to the same genus. But something is said to be an animal as a result of its having a sensory soul. Therefore animal will not be a single genus common to humans and other animals, which is unacceptable.
3. The Philosopher says in The Generation of Animals [736a35-b15] that an embryo is an animal before it is a human being. But this could not be the case if the sensory and intellective souls had the same essence, since it is an animal through the sensory soul and a human being through the intellective soul. Therefore in human beings the sensory and intellective souls do not have a single essence.
4. The Philosopher says in Metaphysics VIII [1043a2-21] that the genus is drawn from the matter, the differentia from the form. But rational, which is the constitutive differentia of human being, is drawn from the intellective soul. Something is said to be an animal, in contrast, because of its having a body that is animated by a sensory soul. Therefore the intellective soul is related to a body animated by a sensory soul just as form is related to matter. Therefore, in a human being, the intellective soul is not the same in essence as the sensory soul, but rather presupposes it, as a material subject.
On the contrary is what is said in On Church Dogma : "We do not say that there are two souls in a single human being (as James and other Syrians write), one an animal soul, which animates the body and mixes with its blood, the other a spiritual soul, which is devoted to reason. We instead say that in a human being one and the same soul gives the body life, by its affiliation, and manages itself, by its reason."
Reply. Plato claimed that within a single body there are different souls, distinct even with respect to their organs. To these souls he attributed the different functions of life: the nutritive soul, he said, was in the liver, the concupiscible in the heart, the cognitive in the brain. Aristotle discredits this view in his De anima [413b13-24], as regards those parts of the soul that use corporeal organs for their functions. For he shows that in the case of animals that live when cut apart, we find in each part the different operations of soul, such as sensation and appetite. But this would not be the case if the different principles of the soul's operations were spread over different parts of the body ── as if those operations were essentially distinct. As regards the intellective soul, however, Aristotle seems to leave room for doubt over whether it is separate from the soul's other parts only conceptually (ratione), or also spatially (loco).
Plato's view certainly could be upheld if one were to suppose that the soul is united to the body not as its form, but as its mover ── as Plato did suppose. For nothing unacceptable seems to follow if different movers move the same moveable object, especially if they do so with respect to different parts. But if we suppose that soul is united to body as its form, then it seems entirely impossible for several, essentially different souls to be within one body. This can be shown through three arguments.
First, an animal with several souls would not be one thing unconditionally. For nothing is unconditionally one except through the one form through which that thing has existence, because a thing's being existent and its being one thing come from the same source. For that reason, things that are characterized by different forms are not one thing unconditionally (e.g., a white human being). Therefore if a human being were to be living through one form (the vegetative soul), an animal through another (the sensory soul), and human through a third (the rational soul), then it would follow that a human being would not be one thing unconditionally. Aristotle argues like this against Plato in Metaphysics VIII [1045a14-20]. If the Idea of animal were different from the Idea of biped then a biped animal would not be one thing unconditionally. For this reason, arguing in De anima I [411b6-14] against those who held that there are different souls in the body, Aristotle asks "what contains" them ── i.e., what makes from them one thing. And it cannot be said that they are united by the body's unity. For it is the soul that contains the body, and that makes it be one thing, rather than vice versa.
Second, this is shown to be impossible through modes of predication. For things that are drawn from different forms are predicated of one another either (i) per accidens, if the forms are not ordered to one another (e.g., when we say that white is sweet); or (ii) if the forms are ordered to one another, the predication will be per se ── in the second mode of speaking per se, since the subject is contained in the definition of the predicate. (A surface, for instance, is a prerequisite for color; therefore if we say that the body's surface is colored, this will be the second mode of per se predication.) Therefore if something were said to be an animal because of one form, and said to be a human being because of another, then it would follow that either (i) one of the forms could be predicated of the other only per accidens, if the two forms did not have any order to one another; or (ii) there would there be predication in the second mode of speaking per se, if one of the souls were a prerequisite for the other. But each of these is clearly false. For (i) animal is predicated of human being per se, not per accidens, and (ii) it is not the case that human being is contained in the definition of animal, but vice versa. Therefore it must be the same form through which something is an animal, and through which something is a human being. Otherwise, the human being would not truly be that which the animal is, in such a way that animal would be predicated per se of human being.
Third, this is shown to be impossible through the fact that one operation of the soul, when intense, impedes another. This could in no way occur if the source of the actions did not come from a single essence.
Accordingly, then, it must be said that the soul in a human being ── sensory, intellective, and nutritive ── is numerically the same. Now, as for how that is the case, this can be easily grasped if one pays attention to the differences among species and forms. For the species and forms of things are found to differ relative to one another in terms of being more and less complete. For example, things with souls are more complete than things without, in the order of things, whereas animals are more complete than plants, and human beings more complete than brute animals. There are also different levels among the individuals of these kinds. For this reason Aristotle, in Metaphysics VIII [1043b36-44a2], likens the species of things to numbers, which differ in species as a unit is added or subtracted. Also, in De anima II [414b19-32] he compares the different souls to species of shapes, one of which contains another. Pentagon, for example, contains tetragon, and exceeds it. In this way, therefore, the intellective soul virtually containsH whatever is possessed by the sensory soul of brute animals and the nutritive soul of plants. So a surface with a pentagonal shape is not tetragonal through one shape and pentagonal through another: for the tetragonal shape would be superfluous, being contained within the pentagonal. In the same way, Socrates is not a human being through one soul and an animal through another; rather, through one and the same soul he is both.
Ad 1. The sensory soul is not incorruptible because it is sensory. Rather, it is made incorruptible by being intellective. So when a soul is merely sensory it is corruptible, but when it has the intellective with the sensory, then it is incorruptible. For although the sensory does not confer incorruptibility, nevertheless it cannot take incorruptibility away from the intellective.
Ad 2. It is not the forms but the composite that is classified by genus or species. But a human being is corruptible, just as other animals are. Hence the difference in corruptible versus incorruptible, which concerns the form, does not make a human being differ in genus from other animals.
Ad 3. An embryo first has a soul that is merely sensory. When that is displaced, a more complete soul arrives, one that is at the same time sensory and intellective. This will be explained more fully below [1a 118.2 ad 2].
Ad 4. It is not required that one treat differences among natural things in terms of the different accounts or conceptions (rationes vel intentiones logicas) that result from how one understands them. For reason can grasp one and the same thing in different ways. So, as was said [cxx], the intellective soul virtually contains whatever the sensory soul has, and more still. It follows, then, that reason can consider separately that which involves the power of the sensory soul ── taken as something incomplete and material. And because reason finds this to be common to humans and other animals, it forms on this basis an account of the genus. Meanwhile, reason takes that in which the intellective soul exceeds the sensory as something formal and perfecting, and on that basis it forms the differentia of human being.
Is there any other substantial form in the human body?
It seems that in a human being there is another form beyond the intellective soul:
1. The Philosopher says in De anima II [412a27-28] that "the soul is the actuality of a physical body potentially having life." Therefore the soul is related to the body as form to matter. But a body has a substantial form through which it is a body. Therefore the body has some substantial form that precedes the soul.
2. A human being, like any animal, is self-moving. But, as is proved in Physics VIII [257b6-13], everything self-moving is divided into two parts, one producing the motion, the other moved. Now the part that produces the motion is the soul. Therefore the other part must be such that it can be moved. But prime matter cannot be moved, as is said in Physics V [225a20-31], because it is a being only in potentiality, whereas everything that is moved is a body. Therefore a human being, and every animal, must have another substantial form, one that gives rise to the body.
3. The ranking of forms is determined by their relationship to prime matter, since prior and posterior are specified by comparison to some starting-point. Therefore if in a human being there were no substantial form beyond the rational soul, and instead it inhered in prime matter without any intermediary, then as a result it would rank among the most imperfect of forms, those that inhere in matter without any intermediary.
4. The human body is a mixed body. But mixture does not occur with respect to the matter alone, because that would be merely corruption. Therefore the forms of the elements must remain in the mixed body, and these are substantial forms. Therefore the human body has other substantial forms beyond the intellective soul.
On the contrary, for one thing there is one substantial being. But a substantial form gives substantial being. Therefore for one thing there is only one substantial form. But the soul is the substantial form of a human being. Therefore it is impossible for a human being to have a substantial form other than the intellective soul.
Reply. If it were supposed that the intellective soul is not united to the body as its form, but only as its mover, as the Platonists supposed, then it would be necessary to say that there is another substantial form in a human being, giving rise to the existence of the body that is moved by the soul. But if the intellective soul is united to the body as its substantial form, as we have already said above [76.1], then it is impossible for any other substantial form beyond it to be found in a human being.
To see this, consider that a substantial formH differs from an accidental formH as follows: an accidental form does not give being unconditionally, but being such. (So heat does not make its subject be unconditionally, but be hot.) And so when an accidental form is added, we do not say that something is made or is generated unconditionally, but that it is made such or that it stands in some way. Likewise, when an accidental form departs, we do not say that something is corrupted unconditionally, but in a certain respect (secundum quid).
A substantial form, on the other hand, gives being unconditionally. So something is said to be generated unconditionally through its addition and, through its removal, to be corrupted unconditionally. That is why the ancient naturalists, who supposed that prime matter is something that actually exists (fire, air, or some such thing), said that nothing is generated or corrupted unconditionally, but that all "coming to be consists in being altered," as is said in Physics I [187a30]. Therefore if it were the case that prior to the intellective soul there were also some other substantial form in the matter, through which the soul's subject were actually existent, then as a result the soul would not make a thing be unconditionally. Consequently it would not be a substantial form, and through the addition of soul there would not be generation unconditionally, nor through its removal corruption unconditionally, but only in a certain respect. These consequences are clearly false.
One must say, then, that a human being has no substantial form other than the intellective soul alone, and that just as it virtually contains the sensory and nutritive souls, so it virtually contains all its lower forms, and that it alone brings about whatever it is that less perfect forms bring about in other things. And the same must be said for the sensory soul in brutes, and the nutritive soul in plants, and generally for all more perfect forms with respect to the less perfect.
Ad 1. Aristotle does not say that the soul is the actuality of body alone, but "the actuality of a physical body with organs" [412b5-6], "potentially having life" ── and it is such a potentiality that he says "does not rule out soul" [412b25]. On this basis it is clear that the soul too is included in that of which it is said to be the actuality. This is said in the same way in which heat is said to be the actuality of what is hot, and light the actuality of what is luminous. It is not that something luminous exists apart from light, but that it is luminous through light. And the soul is likewise said to be "the actuality of a body," etc., because through the soul it is a body, it has organs, and it is potentially having life. But first actuality is spoken of as potential with respect to second actuality, which is the operation. For such a potentiality "does not rule out soul" ── i.e., it does not exclude soul.
Ad 2. The soul moves the body not through its existence, in virtue of which it is united to the body as its form, but through its potential for producing movement, the actualization of which presupposes a body already actualized by soul. In this way, then, the soul is the part producing motion as regards its motive power, whereas the ensouled body is the part that is moved.
Ad 3. There are different levels of perfection to be considered in matter, such as existing, living, sensing, and thinking. But a second thing added onto its predecessor is always more perfect. Therefore a form that provides only the first level of perfection to matter is the most imperfect, whereas a form that provides the first, second, and third degrees (and so on) is the most perfect, and nevertheless [inheres] in matter without any intermediary.
Ad 4. Avicenna claimed that the substantial forms of the elements remain whole in something mixed, and that mixture occurs inasmuch as the contrary qualities of the elements are brought down to a mean state. But this is impossible. For the different forms of the elements cannot exist except in different parts of the matter, and this difference among parts must be understood as involving dimensions, without which there can be no divisible matter. But matter subjected to dimension is found only in a body. Different bodies, however, cannot be in the same place. So it follows that the elements in something mixed would have distinct locations. As a result, this will not be a true mixture, one that occurs throughout the whole, but an apparent mixture, one that occurs through minute [parts] being positioned next to one other.
But Averroes, in De caelo III , claimed that the forms of the elements, because of their imperfection, fall in between accidental and substantial forms: hence they are susceptible to more and less, and hence they are attenuated in the mixture and brought down to a mean state, and out of them flows forth a single form. But this is even more impossible. For the substantial being of any thing lies in something indivisible; every addition and subtraction changes its species (like the case of numbers, as is said in Metaphysics VIII [1043b36-1044a2]). That is why it is impossible for any substantial form to take on more and less. Also, it is no less impossible for something to fall in between substance and accident. And so we must say, in accord with the Philosopher in De generatione I [327b29-31], that in something mixed the forms of the elements remain virtually, not actually. For the distinctive qualities of the elements remain, although attenuated, and in these qualities is the power of the elemental forms. This sort of quality of the mixture is its distinctive disposition for the substantial form of a mixed body ── e.g., the form of stone, or any soul.
Article 5. What sort of body should have the intellective
principle as its form?
It seems inappropriate for the intellective soul to be united to such a [mixed] body.
1. Matter should be proportioned to its form. But the intellective soul is an incorruptible form. Therefore it is not appropriate for it to be united to a corruptible body.
2. The intellective soul is the most immaterial of forms, an indication of which is that it has an operation that bodily matter does not share in. But the less a body has of matter, the more refined it is. Therefore the soul should be united with the most refined of bodies (say, fire) and not with a body that is mixed and more terrestrial.
3. Since the form is the basis of the species, different species do not come from a single form. But the intellective soul is a single form. Therefore, it should not be united to a body composed of parts belonging to dissimilar species.
4. A more perfect form should be received in something more perfect. But the intellective soul is the most perfect of souls. Now the bodies of other animals are naturally endowed with protective coverings such as hair in place of clothing, and hoofs in place of shoes. They also have weapons naturally given to them ── claws, teeth, and horns, for instance. So for this reason it seems that the intellective soul should not have been united to a body that is imperfect in that it lacks such tools.
On the contrary. The Philosopher says in De anima II [412a27-28, b5-6] that "the soul is the actuality of a physical body with organs, potentially having life."
Reply. Form does not exist for the sake of matter; instead, matter exists for the sake of form. Therefore, the reason why matter is such as it is must be drawn from the form, not vice versa. But, as was established above [55.2c], the intellective soul holds the lowest rank among intellectual substances, in terms of natural order. This is so inasmuch as it does not have knowledge of the truth naturally given to it, in the way that the angels do. Instead, it must accumulate such knowledge from divisible things, through sensory means, as Dionysius says in Divine Names 7.2. But when it comes to what is necessary, nature neglects nothing. For this reason the intellective soul needed to have not only the power for thought, but also the power for sensation. But sensory action does not occur without a bodily instrument. Therefore the intellective soul needed to be united to a body of the sort that could serve as an appropriate organ for sensation.
Now all the other senses are founded on touch. But the organ of touch is required to be intermediary between the contraries that touch apprehends: hot and cold, wet and dry, and so on. For in this way it is in potentiality for these contraries, and can sense them. So the more the organ of touch has been brought to a balanced complexion, the more touch will be able to perceive. Now the intellective soul possesses the power of sensation most completely, because that which is inferior exists already, and more perfectly, in that which is superior, as Dionysius says in Divine Names [5.3]. So the body to which the intellective soul is united had to be a mixed body,H and one that, more than any other, developed a balanced complexion. That is why a human being, among all animals, has the best sense of touch, and why, among human beings, those who have a better sense of touch have a better intellect. An indication of this is that we observe that "those with soft flesh are mentally well fit," as is said in De anima II [421a26].
Ad 1. One might perhaps want to evade this objection by saying that the human body was incorruptible before original sin. But this reply does not seem adequate, because the human body was immortal before original sin not by nature, but by a gift of divine grace. Otherwise its immortality would not have been removed by sin, just as the immortality of demons was not.
So we should reply differently, by saying that one finds two kinds of conditions in matter: one selected because it is appropriate to the form, the other following of necessity from a prior disposition. A craftsman, for example, selects iron for the form of a saw, a material that is suited for cutting hard things. But that the teeth of the saw can become dull and rusty, this results of necessity from the matter. In this same way, then, the intellective soul should have a body that has a balanced complexion. But it follows from this, due to necessity on the part of the matter, that it is corruptible.
Now if someone wants to say that God could have escaped this necessity, we should say that as regards the make-up of natural things, one does not consider what God could do, but what is appropriate given the nature of things (as Augustine says in De Genesi ad litteram II [i.2]). Nevertheless, God provided [for us] by supplying a remedy against death, through the gift of grace.
Ad 2. The body is suited to the intellective soul not on account of the intellectual operation considered in its own right, but on account of the sensory power, which requires an organ of balanced complexion. This is why the intellective soul had to be united to a body of that sort, and not with a simple element or with a mixed body in which fire is the dominant quantity. For [in that case] there could be no balanced complexion, because fire's active power would be dominant. But this body, with its balanced complexion, does possess a kind of excellence, in that it is far removed from contraries. In this respect it is in a certain way similar to a celestial body.
Ad 3. It is not the parts of an animal (the eyes, hands, flesh and bones, etc.) that are in a species, but the whole. For this reason it cannot be said, strictly speaking, that they belong to different species, only that they are of different dispositions. And this is true of the intellective soul. For although it is one in essence, nevertheless, due to its perfection, it has multiple powers. Hence for its various operations it needs various dispositions in the parts of the body to which it is united. This is why we see that perfect animals have a greater diversity of parts than do imperfect animals, and that imperfect animals have a greater diversity than do plants.
Ad 4. The intellective soul, because it is capable of grasping universals, has the power for an infinite number of things. For this reason nature could not have limited it to determinate natural judgments or even to determinate tools, whether they be defenses or protective coverings. Other animals were limited in this way: their souls apprehend and have power over certain limited particulars. But in place of all these, human beings naturally have reason and their hands, which are the organs of organs; for through them human beings can equip themselves with instruments of infinitely many kinds, for infinitely many purposes.
Article 6. Is the intellective soul united to its body
through the mediation of any accident?
It seems that the intellective soul is united to its body through the mediation of certain accidental dispositions:
1. Every form is in matter that is appropriate to it and disposed for it. But dispositions for a form are accidents of a certain kind. Therefore certain accidents must be conceived of in matter before the substantial form, and thus before the soul, since the soul is a substantial form.
2. Different forms belonging to a single species require different parts of matter. But different parts of matter can be conceived of only in virtue of a division in dimensive quantities.H Therefore dimensions must be conceived of in matter before substantial forms that are multiplied within a single species.
3. The spiritual is linked to the bodily through the contact of power. But the soul's power is its capacity. Therefore it seems that the soul is united to its body through the mediation of a capacity, which is a kind of accident.
On the contrary. Accident comes after substance both temporally and conceptually (ratione), as is said in Metaphysics VII [1028a32-33]. Therefore an accidental form cannot be conceived of in matter before the soul, which is a substantial form.
Reply. If the soul were united to its body only as a mover, then nothing would prevent there from being ── indeed, it would be necessary for there to be ── certain dispositions serving as intermediaries between the soul and its body. On the soul's side there would have to be a capacity through which it would move the body; on the body's side there would have to be an aptitude of some sort, through which the body would be able to be moved by the soul.
But if the intellective soul is united to the body as its substantial form, as was claimed earlier [76.1], then it is impossible for any accidental disposition to lie as an intermediary between body and soul ── or between any form and its matter. The reason for this is as follows. Because there is a certain order in which matter is in potentiality for all actualities, it must be that which is unconditionally first among actualities which is conceived of first in matter. But the first among all actualities is existence.H Therefore it is impossible to conceive of matter as hot or extended before conceiving of it as actually existing. But it has actual existence through its substantial form, which (as was said earlier [76.4cxx]) provides existence unconditionally. For this reason it is impossible for any accidental dispositions to exist in matter before the substantial form, and consequently not before the soul either.
Ad 1. As is clear from things said already [76.3cxx, 76.4cxx], a more perfect form virtually contains whatever belongs to its lower forms. While remaining one and the same, then, it perfects matter with respect to different degrees of perfection. For it is essentially one and the same form through which a human being is an actual being, a body, living, an animal, and a human being. It is clear, however, that, for each genus, the proper accidents follow from the genus. Matter, then, is conceived of as complete in being before it is conceived of as bodily, and so on for the other cases. Likewise, those accidents that are proper to being are conceived of before matter is conceived of as bodily. And in this way dispositions are conceived of in matter before form: not with respect to every effect that the form has, but with respect to those that are posterior.
Ad 2. Quantitative dimensions are accidents that follow from being bodily, which holds of all matter. Thus matter that is already conceived of as bodily and dimensional can be conceived of as distinct in its different parts, so that as a result it takes on different forms in accord with subsequent degrees of perfection. For although it is essentially the same form that assigns different degrees of perfection to matter, as we have said [ad 1], nevertheless it differs with respect to how it is conceptualized.
Ad 3. A spiritual substance that is united to a body only as a mover is united to it through a capacity or power. But the intellective soul is united to its body as a form, through its existence. Still, it governs and moves the body through its capacity and power.
Article 7. Is the soul united to the body
through the mediation of any other body?
It seems that the soul is united to the body of an animal through the mediation of a body:
1. Augustine says in De Genesi ad litteram VII [xix.25] that "the soul governs the body through light (i.e., fire) and air, which are the [elements] most similar to spirit." But fire and air are bodies. Therefore the soul is united to the human body through the mediation of a body.
2. That seems to be an intermediary between things which, when it is taken away, the union is broken up between things that had been united. But when spirit is gone, the soul is separated from the body. Therefore spirit, which is "a kind of subtle body," is an intermediary in the union between body and soul.
3. Moreover, things that are quite distant are united only through a medium. But the intellective soul is distant from the body, both because it is nonbodily and because it is incorruptible. Therefore it seems to be united to the body through the mediation of something that is an incorruptible body. This seems to be some kind of celestial light that draws the elements together and makes them one.
On the contrary. The Philosopher says in De anima II [412b6-8] that "one need not ask whether the soul and the body are one, just as one does not ask about wax and its shape." But a shape is united to the wax without any intervening body. Therefore so is the soul united to the body.
Reply. If the soul were united to the body only as its mover, as the Platonists say, then it would be appropriate to say that other intermediary bodies intervene between the human soul (or that of any animal) and its body. For it is appropriate that what moves something distant does so through much closer intermediaries.
If, on the other hand, the soul is united to the body as its form, as has already been claimed [76.1], then it is impossible for it to be united to the body through the mediation of a body. The reason for this is that a thing is said to be one in just the way it is said to exist. But a form all by itself, because it is essentially actual, makes a thing actually exist; it does not provide existence through an intermediary. Thus the unity of a thing composed of matter and form comes from the form, which is in its own right united to the matter, as its actuality. Nor is there anything else that unites, except the agent that makes the matter actually exist (as is said in Metaphysics VIII [1045b21-23]).
Thus it is clearly false to posit bodies as intermediaries between a human being's soul and body. Among those who have made this claim, some Platonists held that the intellective soul has an incorruptible body that is naturally united to it, from which it is never separated, and through whose mediation it is united to the corruptible human body. Others held that it is united to the body through the mediation of a bodily spirit. Still others held that it is united to the body through the mediation of a light, which they hold to be a body, and to have the nature of the fifth essence. On this view, the vegetative soul is united to its body through the mediation of light from the sidereal heaven, the sensory soul through the mediation of light from the crystalline heaven, and the intellectual soul through the mediation of light from the Empyrean heaven. This is obviously a laughable invention: first, because light is not a body; also, because the fifth essence, being unalterable, does not enter into the composition of a mixed body materially, but only virtually; finally, because the soul is immediately united to its body as form to matter.
Ad 1. Augustine is speaking of the soul insofar as it moves the body, and consequently he uses the word `governing.' And it is true that it moves the denser parts of the body through the more refined parts. And spirit is the first instrument of the power for movement, as the Philosopher says in De motu animalium [703a9-28].
Ad 2. When spirit is taken away then the union between soul and body is gone: not because spirit is an intermediary, but because the disposition is removed by which the body is disposed for such a union. On the other hand, spirit is an intermediary in the production of movement, as the first instrument of movement.
Ad 3. The soul is exceedingly distant from the body, if one considers the conditions of each one apart from the other. So if each of them were to have existence separately, then many intermediaries would have to intervene. But inasmuch as the soul is the body's form, it does not have existence apart from the body's existence. Rather, by its own existence the soul is immediately united to the body. For in this same way every other form, if considered as an actuality, is also at a great distance from matter, which is a being solely in potentiality.
Article 8. Is the soul whole in each part of the body?
It seems that the soul is not whole in each part of the body.
1. The Philosopher says, in De motu animalium [703a36-b2], "there is no need for the soul to be in each part of the body. As long as it exists in some principal [part] of the body then the other parts have life, inasmuch as they are at the same time naturally suited to carry out their own movement."
2. The soul exists in the body it actualizes. But it is the actuality of a body that has organs. Therefore it exists only in a body that has organs. But not every part of the human body has organs. Therefore the soul is not whole in each part of the body.
3. It is said in De anima II [412b17-25] that just as a part of the soul is related to a part of the body (e.g., sight to the pupil), so the whole soul is related to the animal's whole body. Therefore, if the whole soul exists in each part of the body, it follows that each part of the body is an animal.
4. All of the soul's powers are grounded in the soul's very essence. Therefore, if the soul is whole in each part of the body, it follows that all of the soul's powers exist in each part of the body. As a result, there will be sight in the ear and hearing in the eye, which is absurd.
5. If the whole soul existed in each part of the body, then each part of the body would be immediately dependent on the soul. Therefore it would not be the case that one part depends on another, or that one is more prominent than another, which is plainly false. Therefore the soul is not whole in each part of the body.
On the contrary. Augustine says in De trinitate VI [vi.8] that a soul, "in any given body, is whole in the whole body, and whole in each part of it."
Reply. If the soul were united to the body only as its mover then one could say that it does not exist in each part of the body but only in one part, and that through this part it moves the other parts. (This point was made earlier.) But because the soul is united to the body as its form, it necessarily exists in the whole body and in each part of the body. For it is not one of the body's accidental forms, but its substantial form. A substantial form, however, perfects not only the whole, but each part. For since the whole is made up of parts, a form of the whole that does not give existence to the individual parts of the body is a form that is a composition and ordering (e.g., the form of a house) and such a form is accidental. The soul, on the other hand, is a substantial form, and so it must be the form and actuality not only of the whole, but of each part. And for this reason, just as one does not speak of an animal and a human being once the soul has left ── unless equivocally, in the way we speak of a painted or sculpted animal ── so too for the hand and eye, or flesh and bones, as the Philosopher says. An indication of this is that no part of the body has its proper function once the soul has left, whereas anything that retains its species retains the operation belonging to that species. An actuality, however, exists in what it actualizes. As a result the soul must be in the whole body and in each of its parts.
That the soul is whole in each part of the body can be viewed in the following light. Because the whole is that which is divided into parts, there are three ways of being whole, in keeping with the three kinds of division.
C There is one kind of whole that is divided into quantitative parts, such as a whole line or a whole body.
C There is also the kind of whole that is divided into the parts of its account and essence: as something being defined is divided into the parts of its definition, and something composite is analyzed into matter and form.
C A third kind of whole, that of capacity, is divided into parts based on power.
The first way of being whole is not applicable to forms, unless perhaps accidentally, and then only to those forms that are related to the whole quantity no differently than they are to its parts. This is so for whiteness, which is equally disposed, as regards its defining account, to be in the whole surface and in each part of that surface. For this reason, if the surface is divided then whiteness is divided accidentally. But a form that requires diversity among its parts, such as a soul (especially the soul of complete animals), is not equally disposed toward the whole and its parts. For this reason it is not accidentally divided by a quantitative division. So it is, then, that being a quantitative whole can be attributed to the soul neither per se nor accidentally. But the second way of being whole, which is associated with the perfection of its account and essence, is properly and per se applicable to forms. The same is true for being whole in terms of power, since form is the principle of operation.
So if one asks, with respect to whiteness, whether it is whole in the whole surface and in each part of that surface, then one has to draw a distinction. For if one refers to the quantitative whole that whiteness has accidentally, then it would not be whole in each part of the surface. And the same should be said for being whole in power, since the whiteness of the whole surface is more able to move sight than is the whiteness in any one section of the surface. But if one is referring to being whole in species and essence, then the whiteness is whole in each part of the surface.
Now because the soul is not a whole in the quantitative sense, neither per se nor accidentally (as we have said [cxxx]), it is enough to say that the soul is whole in each part of its body in terms of the wholeness associated with its perfection and essence. It is not whole in each part, however, with respect to being whole in power, because it is not in each part of the body with regard to each of its capacities. Rather, with regard to sight it is in the eye, with regard to hearing it is in the ear, and so on.
Nevertheless it is important to take note that because the soul requires diversity among its parts, it is not related to the whole body and to its parts in the same way. Rather, it is related to the whole first and per se, as to the thing it is properly and proportionately suited to perfect. It is related to the parts of that body secondarily, in virtue of their being associated with the whole.
Ad 1. The Philosopher is talking about the soul's capacity for producing movement.
Ad 2. The soul is the actuality of a body that has organs, inasmuch as that is what is first and proportionately suited to being perfected.
Ad 3. The animal is what is composed of the soul and the whole body, which is what is first and proportionately suited to being perfected by the soul. But in this sense the soul is not in a part of the body, and for that reason there is no need for a part of an animal to be an animal.
Ad 4. Among the soul's capacities, some (namely, intellect and will) are in the soul insofar as it exceeds every capability of the body. Such capacities are consequently said to be in no part of the body. Other capacities are common to the soul and the body, and so there is no need for each of these capacities to be wherever the soul is. They need be only in that part of the body that is proportioned to the operation of such a capacity.
Ad 5. One part of the body is said to be more prominent than another on account of the different capacities for which the body's parts serve as organs. For a part of the body is more prominent when it is the organ of a more prominent capacity, or else when it serves the same capacity in a more prominent way.
 SCG II.65; InDA I.3, I.5; QDSC 2c, 5c; De unitate 3.
 Aristotle, De anima I 2, 403b25-27.
 Aristotle, Physics VII 1, 241b34.
 QDA 1-2; InDA I.2, III.7; II Sent. 1.2.4, 17.2.1; SCG II.56-59; De unitate 3; QDSC 2; QDP 3.9; SCG II.49-51, 69.
 De anima I 1, 403a10-11.
 Ad 1xx.
 Aristotle, De an. III 7, 431a14-17; see 85.1 below.
 SCG II.82; QQ 9.5.1, 10.4.2; QDA 19; QDP 3.11; ST 1a 70.3c, IV Sent. 126.96.36.199 (= ST 3a supp. 70.1).
 1a 50.1c, drawing on Aristotle, De an. III 3, 427a21.
 Nemesius, De natura hominis ch. 6 (pp. 322-23); see Plato, Theaetetus 184c.
 Nemesius, De natura hominis ch. 2 (p. 288); see Plato, Phaedrus 245c-246a.
 For the case of intellect see, e.g., De an. I 10, 408b5-18; III 4, 429a24-27, 429b5. For the senses, see De an. I 1, 403a16-17.
 De an. III 4, 429a29-b4.
 78.1 ad 4.
 SCG II.57, II.83; De unitate 3; De ente 2; InMet VII.9; QDP 3.10; InJob 4; III Sent. 5.3.2, 22.1.1.
 75.2sc, with note.
 Averroes, Metaphysics VII.34.
 Aristotle, Meteorology IV 12, 390a10-11.
 Nemesius, De natura hominis ch. 1 (p. 225); ch. 3 (p. 295). See Plato , Alcibiades 129e (authenticity doubtful).
 75.2 ad 1.
 SCG II.50-51; QQ 3.8; QDSC 1, 9 ad 9; QDA 6; CT I.74-75; De substantiis 5-8, 18; De ente 4. For the similar case of angels: II Sent. 3.1.1; QQ 9.4.1; InDDN IV.1.276-78; ST 1a 50.2; InDT 5.4 ad 4; I Sent. 8.5.2; II Sent. 17.1.2.
 Liber de causis, proposition 24; Boethius, Consolation of Philosophy 5 prose 4.
 Divine Names 5.9.
 Ad 1.
 Boethius, De hebdomadibus axiom 8: "For every composite, existence and it itself are different."Albert made great use of this distinction: see Pegis pp.111-. Also Gilbert de la Porrée, InBDH, super regulam 8 (ML 64, 1321 AC).
 In1C 15.2 [Appendix 6]; CT I.74, I.84; QDA 14; ST 2a2ae 164.1 ad 1; II Sent. 19.1.1; SCG II.55, II.79-84; ST 1a 9.2c, 50.5; QDIA; QQ 10.3.2; InDA III.10.202-49; InMet XII.3 ''2450-2453.
 Genesis 1.24; see ad 1.
 1a 118.1-2.
 SCG II.94; QDA 7; II Sent. 3.1.6.
 On First Principles I.6, I.8, II.9, III.5.
 QDA 1-2; SCG II.56-57, 59, 68-70; De unitate 3; QDSC 2; InDA II.1-4, III.7-8; II Sent. 1.2.4 ad 3; InJob 4; QDV 5.9 ad 14; InMet VIII.5; CT 85.
 The ancient source is Plato: see 76.3cxx. See also William of Auvergne (c. 1180-1249), Tractatus de anima I 7 (pp. 72-73), VI 35 (pp. 194-95).
 De an. III 4, 429a24-27.
 75.2 obj. 2 & ad 2.
 SCG II.59, 73, 75; QDSC 9; QDA 3; CT 85; De unitate 3-5; InDA III.7-8; I Sent. 8.5.2 ad 6; II Sent. 17.2.1.
 75.5cxx, 84.1cxx.
 76.1 ad 1-4, 77.1, 79.1.
 1a 50.4.
 75.6, 77.8, Q89.
 SCG II.58; QDP 3.9 ad 9; QDSC 3; QDA 11; QQ 11.5; CT 90-92; In1C 15.6-7; In1Th 5.2.
 See Averroes, De anima I.90 (p. 121), and Plato, Timaeus 69c-72d, although the details there are quite different. See also Avicenna, Liber de anima V.7 (p. 157).
 De an. II 2, 413b24-29.
 Aristotle, De an. I 3, 406b25-28; see Plato, Timaeus 34c-37c.
 Avicenna, Liber de anima V.7 (pp. 158-59).
 75.4 ad 2, 75.7 ad 3.
 CT 90; QQ 1.4.1, 12.7.1; QDA 9; QDSC 3; SCG II.58, IV.81; InDA II.1.242-88; IV Sent. 188.8.131.52 ad 4 (= ST 3a supp. 79.1 ad 4).
 76.1cxx, 76.3cxx.
 As characterized by Averroes, De generatione I.90.
 Aristotle, Categories 5, 3b32-4a9.
 II Sent. 1.2.4-5; QDM 5.5; QDA 8; SCG II.90; QDSC 6-7.
 75.3 ad 1, 76.1sc.
 84.3, 84.6.
 ST 1a 7.2 obj.2 & ad 2.
 Aristotle, De an. III 8, 432a1-2.
 SCG II.71; QDA 9; InDA II.1.366-92; InMet VIII.5 ''1765-67; QDV 13.4c.
 75.1 ad 3.
 77.1 ad 5.
 QDA 9; II Sent. 1.2.4 ad 3.
 See 1a 51.1 obj.1 & ad 1, where Aquinas criticizes Origen and clarifies a statement made by Bernard of Clairvaux.
 Obj. 2, with note.
 Obj. 3.
 QDA 10; QDSC 4; SCG II.72; InDA I.14; ST 1a 8.2 ad 3; I Sent. 8.5.3.
 76.4 ad 1.
 De an. II 1, 412b5-6; see 76.5sc.
 76.3cxx, 76.4cxx, 76.6cxx, 76.7cxx.
 E.g., De anima II 1, 412b19-22.
 76.4 ad 1.