Whether the Soul Is in Each Part of the Body?
Objection 1: It would seem that the whole soul is not in each part of
the body; for the Philosopher says in _De causa motus animalium_ (De
mot. animal. x): "It is not necessary for the soul to be in each part
of the body; it suffices that it be in some principle of the body
causing the other parts to live, for each part has a natural movement
of its own."
Obj. 2: Further, the soul is in the body of which it is the act. But
it is the act of an organic body. Therefore it exists only in an
organic body. But each part of the human body is not an organic body.
Therefore the whole soul is not in each part.
Obj. 3: Further, the Philosopher says (De Anima ii, 1) that the
relation of a part of the soul to a part of the body, such as the
sight to the pupil of the eye, is the same as the relation of the
soul to the whole body of an animal. If, therefore, the whole soul is
in each part of the body, it follows that each part of the body is an
animal.
Obj. 4: Further, all the powers of the soul are rooted in the essence
of the soul. If, therefore, the whole soul be in each part of the
body, it follows that all the powers of the soul are in each part of
the body; thus the sight will be in the ear, and hearing in the eye,
and this is absurd.
Obj. 5: Further, if the whole soul is in each part of the body, each
part of the body is immediately dependent on the soul. Thus one part
would not depend on another; nor would one part be nobler than
another; which is clearly untrue. Therefore the soul is not in each
part of the body.
_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.
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