Article 4 — Whether the whole soul is in every part of the body

Fourth, it is asked whether the whole soul is in every part of the body. (Parallel texts: In I Sent., d. 8, q. 5, a. 3; SCG II.72; ST I.76.8; Disputed Questions on the Soul, q. 10; Commentary on Aristotle’s On the Soul, bk. 1, lect. 14.)

Obj. 1: And it would seem that it is not. For Aristotle says in his book On the Motion of Animals that there is no need for the soul to be in any one part of the body, but there is need for it to exist in some principle of the body. (Aristotle, On the Motion of Animals 1.10, 703a32,36–37.) Now, in nature nothing is in vain. (Aristotle, On the Soul 3.9, 432b21–22; On the Heavens 2.11, 291b13–14.) Therefore, the soul is not in every part of the body.

Obj. 2: Furthermore, an animal is made up of body and soul. If, then, the soul were in every part of the body, every part of an animal would be an animal, which is incongruous. (Cf. ST I.76.8, obj. 3.)

Obj. 3: Furthermore, in anything in which a subject is, the property of the subject also is. But all the powers of the soul are in the essence of the soul, just as properties are in a subject. Therefore, if the soul were in every part of the body, it would follow that all the powers of the soul were in every part of the body, and thus hearing will be in the eye and sight in the ear, which is incongruous. (Cf. ST I.76.8, obj. 4.)

Obj. 4: Furthermore, no form which demands a dissimilarity of parts is found in every part, as is clear regarding the form “house,” which is not in every part of a house but in the house as a whole. But forms which do not demand a dissimilarity of parts are in the individual parts, as, for instance, the form “fire” and the form “air.” Now, the soul is a form that demands a dissimilarity of parts, as is clear in the case of all animate things. Therefore, the soul is not in every part of the body. (Cf. Aquinas, Disputed Questions on the Soul, q. 10, obj. 17.)

Obj. 5: Furthermore, no form which is extended in correspondence with the extension of matter is entirely in every part of its matter. But the soul is extended in correspondence with the extension of matter. For it is said in the book On the Magnitude of the Soul, I judge the soul to be as large as the extent of the body allows it to be. (Augustine, On the Magnitude of the Soul, bk. 1, ch. 5, para. 7 (CSEL 89:139; PL 32:1039).) Therefore, the soul is not entirely in every part of the body.

Obj. 6: Furthermore, that the soul is in every part of the body seems particularly apparent from the fact that it acts in every part of the body. But the soul acts where it is not; for Augustine says in his Letter to Volusianus, (Augustine, Letter to Volusianus, epistle 137, ch. 2, para. 5 (CSEL 44:103; PL 33:517–18).) the soul feels and sees in the heavens, where it is not. It is not, therefore, necessary for the soul to be in every part of the body.

Obj. 7: Furthermore, according to the Philosopher, (Aristotle, On the Soul 1.3, 406a30–b1; Topics 2.7, 113a29–30.) when we move ourselves, those things which are within us are moved. Now, it may be the case that one part of the body is moved while another is at rest. If, therefore, the soul is in every part of the body, it follows that it is both in motion and at rest at the same time, which seems incongruous.

Obj. 8: Furthermore, if the soul is in every part of the body, each part of the body will have an immediate relation to the soul, and, thus, the other parts will not depend on the heart. This is contrary to Jerome in his Commentary on Matthew, who says that the most important thing in man is not in the brain, as Plato says, but in the heart, as Christ says. (Jerome (ca. 347–419 AD), On Matthew, bk. 2, on Matthew 15:19–20 (PL 26:109A; CCSL 77:131).)

Obj. 9: Furthermore, no form which demands a definite shape can be where that shape is not. But the soul is in the body in connection with a definite shape; for the Commentator says in On the Soul 1 that every animal’s body has its own proper shape, and this fact is evident in the case of the species, for the lion’s members do not differ from the stag’s members except because of the difference of their souls. (Averroes, Commentary on Aristotle’s On the Soul, bk. 1, comm. 53.) Therefore, since the shape of the whole is not found in a part, the soul will not be in a part. And this is what the same Commentator says on the same book, that if the heart has a natural capacity for receiving a soul because it has a particular kind of shape, it is obvious that a part of it does not receive that soul, because a part does not have that particular shape. (Averroes, Commentary on Aristotle’s On the Soul, bk. 1, comm. 94.)

Obj. 10: Furthermore, the more abstract a thing is, so much the less is it limited to something corporeal. But an angel is more abstract than a soul. Now an angel is limited to some part of the movable object which it moves and is not in every part of it, as the Philosopher makes clear in the Physics, (Aristotle, Physics 8.10, 267b7–9.) where he says that the mover of the heavens is not in the center, but in a certain part of the circumference. (Cf. Aquinas, Disputed Questions on the Soul, q. 10, obj. 5.) Much less then is a soul in every part of its body.

Obj. 11: Furthermore, if the soul’s activity is in any particular part of the body, the soul itself is there. And by a parallel argument, in whatever part of the body there is the activity of the power of sight, there is the power of sight. But the activity of the power of sight would be in the foot, if the organ of the power of sight were there; hence, the fact that the activity of sight is not there will be due merely to the absence of the organ. Accordingly, the power of sight will be there if the soul is there.

Obj. 12: Furthermore, if the soul is in every part of the body, it must be the case that wherever a given part of the body is, there is the soul. But in the case of a growing child, parts begin to exist through growth, where they previously were not; therefore, his soul too begins to exist where it previously was not. But this seems impossible. For there are three ways in which a thing begins to exist where it previously was not: either through the fact that something quite new comes into being, as when the soul is created and is infused into the body; or through a changing over of the thing itself, as when the body is changed from place to place; or through the change of another thing into the thing itself, as when Christ’s body begins to exist on the altar. None of these can be said to happen in this case. Therefore, the soul is not in every part of the body.

Obj. 13: Furthermore, the soul is only in the body whose act it is. Now it is the act of an organic body, as On the Soul 2 (Aristotle, On the Soul 2.1, 412a27–28; 412b4–5.) says. Since, then, not every part of the body is an organic body, it will not be in every part of the body. (Cf. ST I.76.8, obj. 2.)

Obj. 14: Furthermore, there is a greater difference between the flesh and the bone of any one man than between the flesh of one man and the flesh of another. But one soul cannot be in two bodies of different men. Therefore, it cannot be in all the parts of any one man.

Obj. 15: Furthermore, if the soul is in every part of the body, it must be the case that if any part of the body is taken away, either the soul must be taken away, which is clearly false, since a man remains alive; or else it must be transferred from that part to other parts, which is impossible, since the soul is simple and consequently immovable. Therefore, it is not in every part of the body.

Obj. 16: Furthermore, nothing that is indivisible can be in anything but an indivisible object, since a place has to be commensurate with what is in that place. (Cf. ST III.57.1, resp.) Now in the body it is possible to specify an indefinite number of indivisibles. If, then, the soul is in every part of the body, it will follow that it is in an indefinite number of places. This cannot be, since it is of finite power.

Obj. 17: Furthermore, since the soul is simple and without dimensional quantity, it seems that no wholeness can possibly be attributed to it save that of power. But it is not in every part of the body as regards its powers, in which the wholeness of its power is considered to be. Therefore, the whole soul is not in every part of the body.

Obj. 18: Furthermore, that a thing can be wholly in a whole and in all parts seems to be due to its simplicity. For in the case of bodies we see that this cannot happen. But the soul is not simple, but is composed of matter and form. Therefore, it is not in every part of the body. Proof of the minor premise: in the Metaphysics, the Philosopher censures those who assert that corporeal matter is the first principle, because they asserted only the elements of bodies, but not of things that do not have bodies. (Aristotle, Metaphysics 1.8, 988b24–25.) There is accordingly some incorporeal element too. But an element is a material principle. Therefore, incorporeal substances also, such as an angel and a soul, have a principle too.

Obj. 19: Furthermore, certain animals live, even when cut in two. (Aristotle, Metaphysics 7.16, 1040b13–14.) For it cannot be said that either of the two parts lives through the whole soul. Therefore, even before the cutting, the whole soul was not in that part, but part of the soul was.

Obj. 20: Furthermore, “whole” and “perfect” are identical, as is said in Physics 3. (Aristotle, Physics 3.6, 207a13–14.) A thing is perfect which attains its proper excellence, as is said in Physics 3. (Aristotle, Physics 7.3, 246b28–29.) Now, the proper excellence of the human soul, as regards the intellect, is not an act of any part of the body. Therefore, the soul is not entirely in every part of the body.

On the contrary (1), there is what Augustine says in On the Trinity 3, that the soul is wholly in the whole being and wholly in every part of it. (Augustine, On the Trinity, bk. 6, ch. 6, para. 8 (PL 42:929; CCSL 50:237).)

Furthermore (2), Damascene says that an angel is where it acts; (John Damascene, On the Orthodox Faith, bk. 1, ch. 13 (PG 94:854A); bk. 2, ch. 3 (PG 94:870C).) by a parallel argument, therefore, so too the soul. But the soul acts in every part of the body, because every part of the body is nourished, grows, and is sensitive. Therefore, the soul is in every part of the body.

Furthermore (3), the soul is of greater power than material forms. But material forms, such as fire or air, are in every part; much more so, therefore, is the soul.

Furthermore (4), it is said in the book The Spirit and the Soul that the soul by its presence vivifies the body. (Alcher of Clairvaux, The Spirit and the Soul, ch. 18 (PL 40:793).) But every part of the body is vivified by the soul. Therefore, the soul is present in every part of the body.

I answer that the truth of this question depends on the preceding ones. For it has previously been pointed out that the soul is united to the body not only as a mover, but as a form. And later on it was shown that a soul does not presuppose in matter other substantial forms, which would give substantial actual being to a body or to its parts, but that both the whole body and all its parts have actual substantial and specific being through the soul, and, when the soul departs, just as “man” or “animal” or “living body” does not remain, so neither “eye” nor “flesh” nor “bone” remain, except in an equivocal sense, like things painted or made of stone. Thus, then, since every act is in that of which it is the act, it must be that the soul, which is the act of the whole body and of all the parts, is in the whole body and in every one of its parts.

Yet the whole body is related in one way to the soul and in another to its parts. For the soul is indeed the act of the whole body primarily and essentially, but of the parts in their relation to the whole. To make this clear, we must consider that, since matter is for the sake of form, the matter must be such as suits the form. In those things which are subject to corruption, the more imperfect forms, which are of weaker power, have few activities, for which dissimilarity of parts is not required, as is clear in the case of all inanimate bodies. But the soul, since it is a form of higher and greater power, can be the principle of different activities, for the carrying out of which dissimilar parts of the body are required. And, consequently, every soul requires a diversity of organs in parts of the body of which it is the act; and all the greater diversity in proportion as the soul is more perfect. Thus, then, the lowest forms perfect their matter in a uniform way, but the soul does this in a non-uniform way, with the result that the entirety of the body of which the soul is primarily and essentially the act is made up of dissimilar parts.

But we still have to inquire into the statement that the soul is wholly in the whole and wholly in each individual part. To make this clear, we must consider that wholeness is primarily and more obviously something based on quantity, inasmuch as a whole is called a “quantum,” which is naturally susceptible of division into quantitative parts. This sort of wholeness cannot be ascribed to forms except in an accidental sense, namely, insofar as they are accidentally divided by the division of a quantity, as whiteness is divided by the division of a surface. But this is characteristic of those forms only which are extended along with quantity. The reason why this latter property belongs to some forms is that they have similar, or almost similar, matter in their whole and in a part. Hence, forms which require great dissimilarity in the parts do not have this sort of extension and wholeness, as, for instance, souls, especially those of perfect animals.

Now, the second kind of wholeness is considered on the basis of the perfection of an essence, and is a wholeness to which essential parts correspond: the physical parts, matter and form, in the case of composites, and the logical parts, genus and difference. This perfection is susceptible of degrees in the case of accidental forms, but not in the case of substantial forms. The third sort of wholeness is on a basis of powers. If, then, we were to speak of a given form which has extension in matter, such as “whiteness,” we might say that the whiteness is wholly in every part by a wholeness of essence and of power, but not by the first sort of wholeness, which belongs to it accidentally. Thus, the whole account of the species “whiteness” is found in every part of the surface; the total quantity which it accidentally possesses, however, is not, but part of this is in a part.

Now, the soul, and especially the human soul, does not have extension in matter. Hence, the first sort of wholeness does not take place in it. The remaining alternative, therefore, is that from the viewpoint of wholeness of essence, it may be stated absolutely that it is wholly in every part of the body; not, however, from the viewpoint of wholeness of power, because the parts are perfected in different ways by the soul itself for different activities, and a definite activity belongs to it, namely, understanding, which it will not perform through any part of the body. Hence, if the soul’s wholeness is taken in the sense of wholeness of power, not only is the soul not wholly in every part, but neither is it wholly in the whole body. For the power of the soul exceeds the body’s capacity, as has been said above. (Above: a. 2, resp.)

Reply Obj. 1: The Philosopher in that passage is speaking of the soul with reference to its power of moving, which is primarily seated in the heart. (Aquinas, Disputed Questions on the Soul, q. 10, ad 4.)

Reply Obj. 2: The soul is not in every part of the body primarily and essentially, but in relation to the whole, as has been said, (Above: resp.) and consequently not every part of an animal is an animal. (Cf. Aquinas, Disputed Questions on the Soul, q. 10, ad 7.)

Reply Obj. 3: According to the Philosopher in his book On Sleep and Sleeplessness, an action belongs to that which has the potency for that action. (Aristotle, On Sleep and Sleeplessness 1, 454a8.) Hence, those powers whose activities do not belong to the soul alone but to the composite are in an organ as in a subject, but in the soul as in their root. Now, only those powers are in the soul as in a subject whose activities the soul does not carry out through an organ of the body, and yet these powers belong to the soul inasmuch as it is superior to the body. Hence, it does not follow that all the powers of the soul are in every part of the body. (Cf. ST I.76.8, ad 4.)

Reply Obj. 4: The form “house,” since it is an accidental form, does not give specific actual being to the individual parts of the house, as the soul gives it to the individual parts of the body. Consequently, there is no comparison. (Cf. Aquinas, Disputed Questions on the Soul, q. 10, ad 16.)

Reply Obj. 5: The passage there quoted is not understood to mean that the human soul is extended in correspondence with the body’s extension, but that the virtual quantity of the soul does not reach out to a greater quantity than that of the body.

Reply Obj. 6: Every activity is somehow understood as intermediate between the one who performs the activity and the object of the activity, either in reality (as in the case of those actions which go out from an agent to something external that is to be changed), or in a figurative sense, as, for instance, understanding, willing, and the like, which, although they are actions that remain within the agent, as is said in Metaphysics 9, (Aristotle, Metaphysics 9.8, 1050a34–b1.) are nevertheless referred to after the fashion of other actions as tending from one thing to another.

Thus, therefore, when someone is said to be acting in this or in that place, that statement can be understood in two senses: in one sense, that by adverbs of this sort the verb is modified from the standpoint of the activity going out from the agent, and in this sense it is true that wherever the soul acts, there it is; in another sense, from the standpoint of the activity’s being understood as terminating in something else, and in this sense it is not true that wherever it acts there it is. For in this latter sense the soul feels and sees in the heavens, inasmuch as the heavens are felt and seen by it.

Reply Obj. 7: The soul, when the body is moved, is moved accidentally and not of itself. Now, it is not incongruous that a thing be at once moved and at rest accidentally, in different respects. It would, however, be incongruous if of itself it were at the same time at rest and being moved. (Cf. Aquinas, Disputed Questions on the Soul, q. 10, ad 12.)

Reply Obj. 8: Although the soul is the act of every part of the body, nevertheless not all parts of the body are perfected by it in a uniform way, as has been said, (Above: resp.) but one part more notably and more perfectly than another. (Cf. ST I.76.8, ad 5.)

Reply Obj. 9: A soul is said to be in a body through a definite shape, not in the sense that the shape is the cause of its being in the body, but rather the shape of the body results from the soul. Hence, where there is no shape suited to “this soul,” “this soul” cannot actually be. But the soul requires one shape in the whole body of which it is in a prior sense the act, and another in a part, of which it is the act in relation to the whole, as has been said. (Above: resp.)

Hence, in the case of animals in which the shape of a part is almost of the same form as the shape of the whole, a part receives the soul as a kind of whole. Therefore, a part that has been cut off is alive. Yet in the case of perfect animals, in which the shape of a part would differ greatly from the shape of the whole, a part does not receive the soul as would something whole and primarily perfectible, so as to be alive when cut off. It does, nevertheless, receive the soul in relation to the whole, so as to be alive when united to the whole.

Reply Obj. 10: An angel is related to the heavenly body which it moves, not as a form but as a mover. Hence, there is no comparison between it and the soul, which is the form of the whole and of every part.

Reply Obj. 11: If the eye were in the foot, the power of sight would be there, because this power is the act of this kind of animate organ. But when the organ is removed, the soul remains there, but the power of sight does not.

Reply Obj. 12: Growth does not occur without local movement, as the Philosopher says in Physics 4. (Aristotle, Physics 4.1, 209a26–29; 4.4, 211a14–17; 4.6, 213b4.) Hence, when a boy grows, just as some part of the body begins to exist on its own account in a place where it previously was not, so also does the soul, in an accidental way, and by a changing over of itself, inasmuch as it is moved in an accidental way when the body is moved.

Reply Obj. 13: The organic body is perfectible by the soul primarily and essentially, whereas the individual organs and parts of organs are perfectible in relation to the whole, as has been said. (Above: resp.; cf. Aquinas, Disputed Questions on the Soul, q. 10, ad 12.)

Reply Obj. 14: My flesh is more in agreement with your flesh, in view of the account of its species, than is my flesh with my bone. But in comparison with the whole, the converse is true; for my flesh and my bone can be so ordered as to constitute one whole, whereas my flesh and your flesh cannot.

Reply Obj. 15: When a part is cut off, it does not follow that the soul is taken away, or that it is changed to another part, unless it were to be asserted that the soul was in that part alone; but it does follow that that part ceases to be perfected by the soul of the whole.

Reply Obj. 16: The soul is not indivisible as a point situated in a continuum is, to whose very account being in a divisible place would be contrary. But the soul is indivisible by being quite apart from the whole genus “continuum.” Hence, it is not contrary to its account if it be in some divisible whole.

Reply Obj. 17: In consequence of the very fact that it is indivisible, it follows that the soul does not have quantitative wholeness. Nor are we left on this account with the conclusion that there is in it merely a wholeness of powers; for there is in it a wholeness based on the account of its essence, as has been said. (Above: resp.)

Reply Obj. 18: The Philosopher in that book (Aristotle, Metaphysics 1.) intends to investigate the principles of all beings, not only material principles, but also formal, efficient, and final ones. (Aristotle, Metaphysics 1.7, 988a18–b21.) Consequently, the natural philosophers of old, (Aristotle, Metaphysics 1.8, 988b24–25.) who laid down only a material cause, which has no place among incorporeal things, are refuted by him. And so, they were not able to lay down the principles of all beings. He does not, therefore, intend to say that there is some material element of incorporeal things, but that those men are to be censured who neglected the principles of incorporeal things, laying down only a material cause.

Reply Obj. 19: In the case of those animals which live when cut in two, there is one soul in act and many in potency. Now, through the act of cutting they are brought forth into actual multiplicity, as happens in the case of all forms which have extension in matter.

Reply Obj. 20: When the soul is said to be wholly in every part, “whole” and “perfect” are understood on a basis of the account of the essence, and not on a basis of the account of power or excellence, as is clear from what has been said above.