Q: Whether the Soul Is in Each Part of the Body?

A: On the contrary,
Augustine says (De Trin. vi, 6), that "in each body the whole soul is in the whole body, and in each part is entire."

I answer that,
As we have said, if the soul were united to the body merely as its motor, we might say that it is not in each part of the body, but only in one part through which it would move the others. But since the soul is united to the body as its form, it must necessarily be in the whole body, and in each part thereof. For it is not an accidental form, but the substantial form of the body. Now the substantial form perfects not only the whole, but each part of the whole. For since a whole consists of parts, a form of the whole which does not give existence to each of the parts of the body, is a form consisting in composition and order, such as the form of a house; and such a form is accidental. But the soul is a substantial form; and therefore it must be the form and the act, not only of the whole, but also of each part. Therefore, on the withdrawal of the soul, as we do not speak of an animal or a man unless equivocally, as we speak of a painted animal or a stone animal; so is it with the hand, the eye, the flesh and bones, as the Philosopher says (De Anima ii, 1). A proof of which is, that on the withdrawal of the soul, no part of the body retains its proper action; although that which retains its species, retains the action of the species. But act is in that which it actuates: wherefore the soul must be in the whole body, and in each part thereof.

That it is entire in each part thereof, may be concluded from this, that since a whole is that which is divided into parts, there are three kinds of totality, corresponding to three kinds of division. There is a whole which is divided into parts of quantity, as a whole line, or a whole body. There is also a whole which is divided into logical and essential parts: as a thing defined is divided into the parts of a definition, and a composite into matter and form. There is, further, a third kind of whole which is potential, divided into virtual parts. The first kind of totality does not apply to forms, except perhaps accidentally; and then only to those forms, which have an indifferent relationship to a quantitative whole and its parts; as whiteness, as far as its essence is concerned, is equally disposed to be in the whole surface and in each part of the surface; and, therefore, the surface being divided, the whiteness is accidentally divided. But a form which requires variety in the parts, such as a soul, and specially the soul of perfect animals, is not equally related to the whole and the parts: hence it is not divided accidentally when the whole is divided. So therefore quantitative totality cannot be attributed to the soul, either essentially or accidentally. But the second kind of totality, which depends on logical and essential perfection, properly and essentially belongs to forms: and likewise the virtual totality, because a form is the principle of operation.

Therefore if it be asked whether the whole whiteness is in the whole surface and in each part thereof, it is necessary to distinguish. If we mean quantitative totality which whiteness has accidentally, then the whole whiteness is not in each part of the surface. The same is to be said of totality of power: since the whiteness which is in the whole surface moves the sight more than the whiteness which is in a small part thereof. But if we mean totality of species and essence, then the whole whiteness is in each part of a surface.

Since, however, the soul has not quantitative totality, neither essentially, nor accidentally, as we have seen; it is enough to say that the whole soul is in each part of the body, by totality of perfection and of essence, but not by totality of power. For it is not in each part of the body, with regard to each of its powers; but with regard to sight, it is in the eye; and with regard to hearing, it is in the ear; and so forth. We must observe, however, that since the soul requires variety of parts, its relation to the whole is not the same as its relation to the parts; for to the whole it is compared primarily and essentially, as to its proper and proportionate perfectible; but to the parts, secondarily, inasmuch as they are ordained to the whole.

Reply Obj. 1: The Philosopher is speaking there of the motive power of the soul.

Reply Obj. 2: The soul is the act of an organic body, as of its primary and proportionate perfectible.

Reply Obj. 3: An animal is that which is composed of a soul and a whole body, which is the soul's primary and proportionate perfectible. Thus the soul is not in a part. Whence it does not follow that a part of an animal is an animal.

Reply Obj. 4: Some of the powers of the soul are in it according as it exceeds the entire capacity of the body, namely the intellect and the will; whence these powers are not said to be in any part of the body. Other powers are common to the soul and body; wherefore each of these powers need not be wherever the soul is, but only in that part of the body, which is adapted to the operation of such a power.

Reply Obj. 5: One part of the body is said to be nobler than another, on account of the various powers, of which the parts of the body are the organs. For that part which is the organ of a nobler power, is a nobler part of the body: as also is that part which serves the same power in a nobler manner.

QUESTION 77

OF THOSE THINGS WHICH BELONG TO THE POWERS OF THE SOUL IN GENERAL (In Eight Articles)

We proceed to consider those things which belong to the powers of the soul; first, in general, secondly, in particular. Under the first head there are eight points of inquiry:

(1) Whether the essence of the soul is its power?

(2) Whether there is one power of the soul, or several?

(3) How the powers of the soul are distinguished from one another?

(4) Of the orders of the powers, one to another;

(5) Whether the powers of the soul are in it as in their subject?

(6) Whether the powers flow from the essence of the soul?

(7) Whether one power rises from another?

(8) Whether all the powers of the soul remain in the soul after death?