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St. Thomas Aquinas
Summa Theologica

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  • FIRST PART (FP: QQ 1-119)
      • Aquin.: SMT FP Q[76] Out. Para. 1/1 - OF THE UNION OF BODY AND SOUL (EIGHT ARTICLES)
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Aquin.: SMT FP Q[76] Out. Para. 1/1 - OF THE UNION OF BODY AND SOUL (EIGHT ARTICLES)

We now consider the union of the soul with the body; and concerning this
there are eight points of inquiry:

(1) Whether the intellectual principle is united to the body as its form?

(2) Whether the intellectual principle is multiplied numerically
according to the number of bodies; or is there one intelligence for all
men?

(3) Whether in the body the form of which is an intellectual principle,
there is some other soul?

(4) Whether in the body there is any other substantial form?

(5) Of the qualities required in the body of which the intellectual
principle is the form?

(6) Whether it be united to such a body by means of another body?

(7) Whether by means of an accident?

(8) Whether the soul is wholly in each part of the body?


Aquin.: SMT FP Q[76] A[1] Thes. Para. 1/1

Whether the intellectual principle is united to the body as its form?

Aquin.: SMT FP Q[76] A[1] Obj. 1 Para. 1/1

OBJ 1: It seems that the intellectual principle is not united to the
body as its form. For the Philosopher says (De Anima iii, 4) that the
intellect is "separate," and that it is not the act of any body.
Therefore it is not united to the body as its form.

Aquin.: SMT FP Q[76] A[1] Obj. 2 Para. 1/1

OBJ 2: Further, every form is determined according to the nature of the
matter of which it is the form; otherwise no proportion would be
required between matter and form. Therefore if the intellect were united
to the body as its form, since every body has a determinate nature, it
would follow that the intellect has a determinate nature; and thus, it
would not be capable of knowing all things, as is clear from what has
been said (Q[75], A[2]); which is contrary to the nature of the
intellect. Therefore the intellect is not united to the body as its form.

Aquin.: SMT FP Q[76] A[1] Obj. 3 Para. 1/1

OBJ 3: Further, whatever receptive power is an act of a body, receives a
form materially and individually; for what is received must be received
according to the condition of the receiver. But the form of the thing
understood is not received into the intellect materially and
individually, but rather immaterially and universally: otherwise the
intellect would not be capable of the knowledge of immaterial and
universal objects, but only of individuals, like the senses. Therefore
the intellect is not united to the body as its form.

Aquin.: SMT FP Q[76] A[1] Obj. 4 Para. 1/1

OBJ 4: Further, power and action have the same subject; for the same
subject is what can, and does, act. But the intellectual action is not
the action of a body, as appears from above (Q[75], A[2]). Therefore
neither is the intellectual faculty a power of the body. But virtue or
power cannot be more abstract or more simple than the essence from which
the faculty or power is derived. Therefore neither is the substance of
the intellect the form of a body.

Aquin.: SMT FP Q[76] A[1] Obj. 5 Para. 1/1

OBJ 5: Further, whatever has "per se" existence is not united to the
body as its form; because a form is that by which a thing exists: so that
the very existence of a form does not belong to the form by itself. But
the intellectual principle has "per se" existence and is subsistent, as
was said above (Q[75], A[2]). Therefore it is not united to the body as
its form.

Aquin.: SMT FP Q[76] A[1] Obj. 6 Para. 1/1

OBJ 6: Further, whatever exists in a thing by reason of its nature
exists in it always. But to be united to matter belongs to the form by
reason of its nature; because form is the act of matter, not by an
accidental quality, but by its own essence; otherwise matter and form
would not make a thing substantially one, but only accidentally one.
Therefore a form cannot be without its own proper matter. But the
intellectual principle, since it is incorruptible, as was shown above
(Q[75], A[6]), remains separate from the body, after the dissolution of
the body. Therefore the intellectual principle is not united to the body
as its form.

Aquin.: SMT FP Q[76] A[1] OTC Para. 1/1

On the contrary, According to the Philosopher, Metaph. viii (Did. vii
2), difference is derived from the form. But the difference which
constitutes man is "rational," which is applied to man on account of his
intellectual principle. Therefore the intellectual principle is the form
of man.

Aquin.: SMT FP Q[76] A[1] Body Para. 1/8

I answer that, We must assert that the intellect which is the principle
of intellectual operation is the form of the human body. For that whereby
primarily anything acts is a form of the thing to which the act is to be
attributed: for instance, that whereby a body is primarily healed is
health, and that whereby the soul knows primarily is knowledge; hence
health is a form of the body, and knowledge is a form of the soul. The
reason is because nothing acts except so far as it is in act; wherefore a
thing acts by that whereby it is in act. Now it is clear that the first
thing by which the body lives is the soul. And as life appears through
various operations in different degrees of living things, that whereby we
primarily perform each of all these vital actions is the soul. For the
soul is the primary principle of our nourishment, sensation, and local
movement; and likewise of our understanding. Therefore this principle by
which we primarily understand, whether it be called the intellect or the
intellectual soul, is the form of the body. This is the demonstration
used by Aristotle (De Anima ii, 2).

Aquin.: SMT FP Q[76] A[1] Body Para. 2/8

But if anyone says that the intellectual soul is not the form of the
body he must first explain how it is that this action of understanding is
the action of this particular man; for each one is conscious that it is
himself who understands. Now an action may be attributed to anyone in
three ways, as is clear from the Philosopher (Phys. v, 1); for a thing is
said to move or act, either by virtue of its whole self, for instance, as
a physician heals; or by virtue of a part, as a man sees by his eye; or
through an accidental quality, as when we say that something that is
white builds, because it is accidental to the builder to be white. So
when we say that Socrates or Plato understands, it is clear that this is
not attributed to him accidentally; since it is ascribed to him as man,
which is predicated of him essentially. We must therefore say either that
Socrates understands by virtue of his whole self, as Plato maintained,
holding that man is an intellectual soul; or that intelligence is a part
of Socrates. The first cannot stand, as was shown above (Q[75], A[4]),
for this reason, that it is one and the same man who is conscious both
that he understands, and that he senses. But one cannot sense without a
body: therefore the body must be some part of man. It follows therefore
that the intellect by which Socrates understands is a part of Socrates,
so that in some way it is united to the body of Socrates.

Aquin.: SMT FP Q[76] A[1] Body Para. 3/8

The Commentator held that this union is through the intelligible
species, as having a double subject, in the possible intellect, and in
the phantasms which are in the corporeal organs. Thus through the
intelligible species the possible intellect is linked to the body of this
or that particular man. But this link or union does not sufficiently
explain the fact, that the act of the intellect is the act of Socrates.
This can be clearly seen from comparison with the sensitive faculty, from
which Aristotle proceeds to consider things relating to the intellect.
For the relation of phantasms to the intellect is like the relation of
colors to the sense of sight, as he says De Anima iii, 5,7. Therefore, as
the species of colors are in the sight, so are the species of phantasms
in the possible intellect. Now it is clear that because the colors, the
images of which are in the sight, are on a wall, the action of seeing is
not attributed to the wall: for we do not say that the wall sees, but
rather that it is seen. Therefore, from the fact that the species of
phantasms are in the possible intellect, it does not follow that
Socrates, in whom are the phantasms, understands, but that he or his
phantasms are understood.

Aquin.: SMT FP Q[76] A[1] Body Para. 4/8

Some, however, tried to maintain that the intellect is united to the
body as its motor; and hence that the intellect and body form one thing
so that the act of the intellect could be attributed to the whole. This
is, however, absurd for many reasons. First, because the intellect does
not move the body except through the appetite, the movement of which
presupposes the operation of the intellect. The reason therefore why
Socrates understands is not because he is moved by his intellect, but
rather, contrariwise, he is moved by his intellect because he
understands. Secondly, because since Socrates is an individual in a
nature of one essence composed of matter and form, if the intellect be
not the form, it follows that it must be outside the essence, and then
the intellect is the whole Socrates as a motor to the thing moved.
Whereas the act of intellect remains in the agent, and does not pass into
something else, as does the action of heating. Therefore the action of
understanding cannot be attributed to Socrates for the reason that he is
moved by his intellect. Thirdly, because the action of a motor is never
attributed to the thing moved, except as to an instrument; as the action
of a carpenter to a saw. Therefore if understanding is attributed to
Socrates, as the action of what moves him, it follows that it is
attributed to him as to an instrument. This is contrary to the teaching
of the Philosopher, who holds that understanding is not possible through
a corporeal instrument (De Anima iii, 4). Fourthly, because, although the
action of a part be attributed to the whole, as the action of the eye is
attributed to a man; yet it is never attributed to another part, except
perhaps indirectly; for we do not say that the hand sees because the eye
sees. Therefore if the intellect and Socrates are united in the above
manner, the action of the intellect cannot be attributed to Socrates. If,
however, Socrates be a whole composed of a union of the intellect with
whatever else belongs to Socrates, and still the intellect be united to
those other things only as a motor, it follows that Socrates is not one
absolutely, and consequently neither a being absolutely, for a thing is a
being according as it is one.

Aquin.: SMT FP Q[76] A[1] Body Para. 5/8

There remains, therefore, no other explanation than that given by
Aristotle - namely, that this particular man understands, because the
intellectual principle is his form. Thus from the very operation of the
intellect it is made clear that the intellectual principle is united to
the body as its form.

Aquin.: SMT FP Q[76] A[1] Body Para. 6/8

The same can be clearly shown from the nature of the human species. For
the nature of each thing is shown by its operation. Now the proper
operation of man as man is to understand; because he thereby surpasses
all other animals. Whence Aristotle concludes (Ethic. x, 7) that the
ultimate happiness of man must consist in this operation as properly
belonging to him. Man must therefore derive his species from that which
is the principle of this operation. But the species of anything is
derived from its form. It follows therefore that the intellectual
principle is the proper form of man.

Aquin.: SMT FP Q[76] A[1] Body Para. 7/8

But we must observe that the nobler a form is, the more it rises above
corporeal matter, the less it is merged in matter, and the more it excels
matter by its power and its operation; hence we find that the form of a
mixed body has another operation not caused by its elemental qualities.
And the higher we advance in the nobility of forms, the more we find that
the power of the form excels the elementary matter; as the vegetative
soul excels the form of the metal, and the sensitive soul excels the
vegetative soul. Now the human soul is the highest and noblest of forms.
Wherefore it excels corporeal matter in its power by the fact that it has
an operation and a power in which corporeal matter has no share whatever.
This power is called the intellect.

Aquin.: SMT FP Q[76] A[1] Body Para. 8/8

It is well to remark that if anyone holds that the soul is composed of
matter and form, it would follow that in no way could the soul be the
form of the body. For since the form is an act, and matter is only in
potentiality, that which is composed of matter and form cannot be the
form of another by virtue of itself as a whole. But if it is a form by
virtue of some part of itself, then that part which is the form we call
the soul, and that of which it is the form we call the "primary animate,"
as was said above (Q[75], A[5]).

Aquin.: SMT FP Q[76] A[1] R.O. 1 Para. 1/2

Reply OBJ 1: As the Philosopher says (Phys. ii, 2), the ultimate natural
form to which the consideration of the natural philosopher is directed is
indeed separate; yet it exists in matter. He proves this from the fact
that "man and the sun generate man from matter." It is separate indeed
according to its intellectual power, because the intellectual power does
not belong to a corporeal organ, as the power of seeing is the act of the
eye; for understanding is an act which cannot be performed by a corporeal
organ, like the act of seeing. But it exists in matter so far as the soul
itself, to which this power belongs, is the form of the body, and the
term of human generation. And so the Philosopher says (De Anima iii) that
the intellect is separate, because it is not the faculty of a corporeal
organ.

Aquin.: SMT FP Q[76] A[1] R.O. 1 Para. 2/2

From this it is clear how to answer the Second and Third objections:
since, in order that man may be able to understand all things by means of
his intellect, and that his intellect may understand immaterial things
and universals, it is sufficient that the intellectual power be not the
act of the body.

Aquin.: SMT FP Q[76] A[1] R.O. 4 Para. 1/1

Reply OBJ 4: The human soul, by reason of its perfection, is not a form
merged in matter, or entirely embraced by matter. Therefore there is
nothing to prevent some power thereof not being the act of the body,
although the soul is essentially the form of the body.

Aquin.: SMT FP Q[76] A[1] R.O. 5 Para. 1/1

Reply OBJ 5: The soul communicates that existence in which it subsists
to the corporeal matter, out of which and the intellectual soul there
results unity of existence; so that the existence of the whole composite
is also the existence of the soul. This is not the case with other
non-subsistent forms. For this reason the human soul retains its own
existence after the dissolution of the body; whereas it is not so with
other forms.

Aquin.: SMT FP Q[76] A[1] R.O. 6 Para. 1/1

Reply OBJ 6: To be united to the body belongs to the soul by reason of
itself, as it belongs to a light body by reason of itself to be raised
up. And as a light body remains light, when removed from its proper
place, retaining meanwhile an aptitude and an inclination for its proper
place; so the human soul retains its proper existence when separated from
the body, having an aptitude and a natural inclination to be united to
the body.


Aquin.: SMT FP Q[76] A[2] Thes. Para. 1/1

Whether the intellectual principle is multiplied according to the number
of bodies?

Aquin.: SMT FP Q[76] A[2] Obj. 1 Para. 1/1

OBJ 1: It would seem that the intellectual principle is not multiplied
according to the number of bodies, but that there is one intellect in all
men. For an immaterial substance is not multiplied in number within one
species. But the human soul is an immaterial substance; since it is not
composed of matter and form as was shown above (Q[75], A[5]). Therefore
there are not many human souls in one species. But all men are of one
species. Therefore there is but one intellect in all men.

Aquin.: SMT FP Q[76] A[2] Obj. 2 Para. 1/1

OBJ 2: Further, when the cause is removed, the effect is also removed.
Therefore, if human souls were multiplied according to the number of
bodies, it follows that the bodies being removed, the number of souls
would not remain; but from all the souls there would be but a single
remainder. This is heretical; for it would do away with the distinction
of rewards and punishments.

Aquin.: SMT FP Q[76] A[2] Obj. 3 Para. 1/1

OBJ 3: Further, if my intellect is distinct from your intellect, my
intellect is an individual, and so is yours; for individuals are things
which differ in number but agree in one species. Now whatever is received
into anything must be received according to the condition of the
receiver. Therefore the species of things would be received individually
into my intellect, and also into yours: which is contrary to the nature
of the intellect which knows universals.

Aquin.: SMT FP Q[76] A[2] Obj. 4 Para. 1/1

OBJ 4: Further, the thing understood is in the intellect which
understands. If, therefore, my intellect is distinct from yours, what is
understood by me must be distinct from what is understood by you; and
consequently it will be reckoned as something individual, and be only
potentially something understood; so that the common intention will have
to be abstracted from both; since from things diverse something
intelligible common to them may be abstracted. But this is contrary to
the nature of the intellect; for then the intellect would seem not to be
distinct from the imagination. It seems, therefore, to follow that there
is one intellect in all men.

Aquin.: SMT FP Q[76] A[2] Obj. 5 Para. 1/1

OBJ 5: Further, when the disciple receives knowledge from the master, it
cannot be said that the master's knowledge begets knowledge in the
disciple, because then also knowledge would be an active form, such as
heat is, which is clearly false. It seems, therefore, that the same
individual knowledge which is in the master is communicated to the
disciple; which cannot be, unless there is one intellect in both.
Seemingly, therefore, the intellect of the disciple and master is but
one; and, consequently, the same applies to all men.

Aquin.: SMT FP Q[76] A[2] Obj. 6 Para. 1/1

OBJ 6: Further, Augustine (De Quant. Animae xxxii) says: "If I were to
say that there are many human souls, I should laugh at myself." But the
soul seems to be one chiefly on account of the intellect. Therefore there
is one intellect of all men.

Aquin.: SMT FP Q[76] A[2] OTC Para. 1/1

On the contrary, The Philosopher says (Phys. ii, 3) that the relation of
universal causes to universals is like the relation of particular causes
to individuals. But it is impossible that a soul, one in species, should
belong to animals of different species. Therefore it is impossible that
one individual intellectual soul should belong to several individuals.

Aquin.: SMT FP Q[76] A[2] Body Para. 1/4

I answer that, It is absolutely impossible for one intellect to belong
to all men. This is clear if, as Plato maintained, man is the intellect
itself. For it would follow that Socrates and Plato are one man; and that
they are not distinct from each other, except by something outside the
essence of each. The distinction between Socrates and Plato would be no
other than that of one man with a tunic and another with a cloak; which
is quite absurd.

Aquin.: SMT FP Q[76] A[2] Body Para. 2/4

It is likewise clear that this is impossible if, according to the
opinion of Aristotle (De Anima ii, 2), it is supposed that the intellect
is a part or a power of the soul which is the form of man. For it is
impossible for many distinct individuals to have one form, as it is
impossible for them to have one existence, for the form is the principle
of existence.

Aquin.: SMT FP Q[76] A[2] Body Para. 3/4

Again, this is clearly impossible, whatever one may hold as to the
manner of the union of the intellect to this or that man. For it is
manifest that, supposing there is one principal agent, and two
instruments, we can say that there is one agent absolutely, but several
actions; as when one man touches several things with his two hands, there
will be one who touches, but two contacts. If, on the contrary, we
suppose one instrument and several principal agents, we might say that there are several agents, but one act; for example, if there be many
drawing a ship by means of a rope; there will be many drawing, but one
pull. If, however, there is one principal agent, and one instrument, we
say that there is one agent and one action, as when the smith strikes
with one hammer, there is one striker and one stroke. Now it is clear
that no matter how the intellect is united or coupled to this or that
man, the intellect has the precedence of all the other things which
appertain to man; for the sensitive powers obey the intellect, and are at
its service. Therefore, if we suppose two men to have several intellects
and one sense - for instance, if two men had one eye - there would be
several seers, but one sight. But if there is one intellect, no matter
how diverse may be all those things of which the intellect makes use as
instruments, in no way is it possible to say that Socrates and Plato are
otherwise than one understanding man. And if to this we add that to
understand, which is the act of the intellect, is not affected by any
organ other than the intellect itself; it will further follow that there
is but one agent and one action: that is to say that all men are but one
"understander," and have but one act of understanding, in regard, that
is, of one intelligible object.

Aquin.: SMT FP Q[76] A[2] Body Para. 4/4

However, it would be possible to distinguish my intellectual action form
yours by the distinction of the phantasms - that is to say, were there
one phantasm of a stone in me, and another in you - if the phantasm
itself, as it is one thing in me and another in you, were a form of the
possible intellect; since the same agent according to divers forms
produces divers actions; as, according to divers forms of things with
regard to the same eye, there are divers visions. But the phantasm itself
is not a form of the possible intellect; it is the intelligible species
abstracted from the phantasm that is a form. Now in one intellect, from
different phantasms of the same species, only one intelligible species is
abstracted; as appears in one man, in whom there may be different
phantasms of a stone; yet from all of them only one intelligible species
of a stone is abstracted; by which the intellect of that one man, by one
operation, understands the nature of a stone, notwithstanding the
diversity of phantasms. Therefore, if there were one intellect for all
men, the diversity of phantasms which are in this one and that one would
not cause a diversity of intellectual operation in this man and that man.
It follows, therefore, that it is altogether impossible and unreasonable
to maintain that there exists one intellect for all men.

Aquin.: SMT FP Q[76] A[2] R.O. 1 Para. 1/1

Reply OBJ 1: Although the intellectual soul, like an angel, has no
matter from which it is produced, yet it is the form of a certain matter;
in which it is unlike an angel. Therefore, according to the division of
matter, there are many souls of one species; while it is quite impossible
for many angels to be of one species.

Aquin.: SMT FP Q[76] A[2] R.O. 2 Para. 1/1

Reply OBJ 2: Everything has unity in the same way that it has being;
consequently we must judge of the multiplicity of a thing as we judge of
its being. Now it is clear that the intellectual soul, by virtue of its
very being, is united to the body as its form; yet, after the dissolution
of the body, the intellectual soul retains its own being. In like manner
the multiplicity of souls is in proportion to the multiplicity of the
bodies; yet, after the dissolution of the bodies, the souls retain their
multiplied being.

Aquin.: SMT FP Q[76] A[2] R.O. 3 Para. 1/1

Reply OBJ 3: Individuality of the intelligent being, or of the species
whereby it understands, does not exclude the understanding of universals;
otherwise, since separate intellects are subsistent substances, and
consequently individual, they could not understand universals. But the
materiality of the knower, and of the species whereby it knows, impedes
the knowledge of the universal. For as every action is according to the
mode of the form by which the agent acts, as heating is according to the
mode of the heat; so knowledge is according to the mode of the species by
which the knower knows. Now it is clear that common nature becomes
distinct and multiplied by reason of the individuating principles which
come from the matter. Therefore if the form, which is the means of
knowledge, is material - that is, not abstracted from material
conditions - its likeness to the nature of a species or genus will be
according to the distinction and multiplication of that nature by means
of individuating principles; so that knowledge of the nature of a thing
in general will be impossible. But if the species be abstracted from the
conditions of individual matter, there will be a likeness of the nature
without those things which make it distinct and multiplied; thus there
will be knowledge of the universal. Nor does it matter, as to this
particular point, whether there be one intellect or many; because, even
if there were but one, it would necessarily be an individual intellect,
and the species whereby it understands, an individual species.

Aquin.: SMT FP Q[76] A[2] R.O. 4 Para. 1/1

Reply OBJ 4: Whether the intellect be one or many, what is understood is
one; for what is understood is in the intellect, not according to its own
nature, but according to its likeness; for "the stone is not in the soul,
but its likeness is," as is said, De Anima iii, 8. Yet it is the stone
which is understood, not the likeness of the stone; except by a
reflection of the intellect on itself: otherwise, the objects of sciences
would not be things, but only intelligible species. Now it happens that
different things, according to different forms, are likened to the same
thing. And since knowledge is begotten according to the assimilation of
the knower to the thing known, it follows that the same thing may happen
to be known by several knowers; as is apparent in regard to the senses;
for several see the same color, according to different likenesses. In the
same way several intellects understand one object understood. But there
is this difference, according to the opinion of Aristotle, between the
sense and the intelligence - that a thing is perceived by the sense
according to the disposition which it has outside the soul - that is, in
its individuality; whereas the nature of the thing understood is indeed
outside the soul, but the mode according to which it exists outside the
soul is not the mode according to which it is understood. For the common
nature is understood as apart from the individuating principles; whereas
such is not its mode of existence outside the soul. But, according to the
opinion of Plato, the thing understood exists outside the soul in the
same condition as those under which it is understood; for he supposed
that the natures of things exist separate from matter.

Aquin.: SMT FP Q[76] A[2] R.O. 5 Para. 1/1

Reply OBJ 5: One knowledge exists in the disciple and another in the
master. How it is caused will be shown later on (Q[117], A[1]).

Aquin.: SMT FP Q[76] A[2] R.O. 6 Para. 1/1

Reply OBJ 6: Augustine denies a plurality of souls, that would involve a
plurality of species.


Aquin.: SMT FP Q[76] A[3] Thes. Para. 1/1

Whether besides the intellectual soul there are in man other souls
essentially different from one another?
Aquin.: SMT FP Q[76] A[3] Obj. 1 Para. 1/1

OBJ 1: It would seem that besides the intellectual soul there are in man
other souls essentially different from one another, such as the sensitive
soul and the nutritive soul. For corruptible and incorruptible are not of
the same substance. But the intellectual soul is incorruptible; whereas
the other souls, as the sensitive and the nutritive, are corruptible, as
was shown above (Q[75], A[6]). Therefore in man the essence of the
intellectual soul, the sensitive soul, and the nutritive soul, cannot be
the same.

Aquin.: SMT FP Q[76] A[3] Obj. 2 Para. 1/1

OBJ 2: Further, if it be said that the sensitive soul in man is
incorruptible; on the contrary, "corruptible and incorruptible differ
generically," says the Philosopher, Metaph. x (Did. ix, 10). But the
sensitive soul in the horse, the lion, and other brute animals, is
corruptible. If, therefore, in man it be incorruptible, the sensitive
soul in man and brute animals will not be of the same "genus." Now an
animal is so called from its having a sensitive soul; and, therefore,
"animal" will not be one genus common to man and other animals, which is
absurd.

Aquin.: SMT FP Q[76] A[3] Obj. 3 Para. 1/1

OBJ 3: Further, the Philosopher says, Metaph. viii (Did. vii, 2), that
the genus is taken from the matter, and difference from the form. But
"rational," which is the difference constituting man, is taken from the
intellectual soul; while he is called "animal" by reason of his having a
body animated by a sensitive soul. Therefore the intellectual soul may be
compared to the body animated by a sensitive soul, as form to matter.
Therefore in man the intellectual soul is not essentially the same as the
sensitive soul, but presupposes it as a material subject.

Aquin.: SMT FP Q[76] A[3] OTC Para. 1/1

On the contrary, It is said in the book De Ecclesiasticis Dogmatibus xv:
"Nor do we say that there are two souls in one man, as James and other
Syrians write; one, animal, by which the body is animated, and which is
mingled with the blood; the other, spiritual, which obeys the reason; but
we say that it is one and the same soul in man, that both gives life to
the body by being united to it, and orders itself by its own reasoning."

Aquin.: SMT FP Q[76] A[3] Body Para. 1/6

I answer that, Plato held that there were several souls in one body,
distinct even as to organs, to which souls he referred the different
vital actions, saying that the nutritive power is in the liver, the
concupiscible in the heart, and the power of knowledge in the brain.
Which opinion is rejected by Aristotle (De Anima ii, 2), with regard to
those parts of the soul which use corporeal organs; for this reason, that
in those animals which continue to live when they have been divided in
each part are observed the operations of the soul, as sense and appetite.
Now this would not be the case if the various principles of the soul's
operations were essentially different, and distributed in the various
parts of the body. But with regard to the intellectual part, he seems to
leave it in doubt whether it be "only logically" distinct from the other
parts of the soul, "or also locally."

Aquin.: SMT FP Q[76] A[3] Body Para. 2/6

The opinion of Plato might be maintained if, as he held, the soul was
supposed to be united to the body, not as its form, but as its motor. For
it involves nothing unreasonable that the same movable thing be moved by
several motors; and still less if it be moved according to its various
parts. If we suppose, however, that the soul is united to the body as its
form, it is quite impossible for several essentially different souls to
be in one body. This can be made clear by three different reasons.

Aquin.: SMT FP Q[76] A[3] Body Para. 3/6

In the first place, an animal would not be absolutely one, in which
there were several souls. For nothing is absolutely one except by one
form, by which a thing has existence: because a thing has from the same
source both existence and unity; and therefore things which are
denominated by various forms are not absolutely one; as, for instance, "a
white man." If, therefore, man were 'living' by one form, the vegetative
soul, and 'animal' by another form, the sensitive soul, and "man" by
another form, the intellectual soul, it would follow that man is not
absolutely one. Thus Aristotle argues, Metaph. viii (Did. vii, 6),
against Plato, that if the idea of an animal is distinct from the idea of
a biped, then a biped animal is not absolutely one. For this reason,
against those who hold that there are several souls in the body, he asks
(De Anima i, 5), "what contains them?" - that is, what makes them one? It
cannot be said that they are united by the one body; because rather does
the soul contain the body and make it one, than the reverse.

Aquin.: SMT FP Q[76] A[3] Body Para. 4/6

Secondly, this is proved to be impossible by the manner in which one
thing is predicated of another. Those things which are derived from
various forms are predicated of one another, either accidentally, (if the
forms are not ordered to one another, as when we say that something white
is sweet), or essentially, in the second manner of essential predication,
(if the forms are ordered one to another, the subject belonging to the
definition of the predicate; as a surface is presupposed to color; so
that if we say that a body with a surface is colored, we have the second
manner of essential predication.) Therefore, if we have one form by which
a thing is an animal, and another form by which it is a man, it follows
either that one of these two things could not be predicated of the other,
except accidentally, supposing these two forms not to be ordered to one
another - or that one would be predicated of the other according to the
second manner of essential predication, if one soul be presupposed to the
other. But both of these consequences are clearly false: because "animal"
is predicated of man essentially and not accidentally; and man is not
part of the definition of an animal, but the other way about. Therefore
of necessity by the same form a thing is animal and man; otherwise man
would not really be the thing which is an animal, so that animal can be
essentially predicated of man.

Aquin.: SMT FP Q[76] A[3] Body Para. 5/6

Thirdly, this is shown to be impossible by the fact that when one
operation of the soul is intense it impedes another, which could never be
the case unless the principle of action were essentially one.

Aquin.: SMT FP Q[76] A[3] Body Para. 6/6

We must therefore conclude that in man the sensitive soul, the
intellectual soul, and the nutritive soul are numerically one soul. This
can easily be explained, if we consider the differences of species and
forms. For we observe that the species and forms of things differ from
one another, as the perfect and imperfect; as in the order of things, the
animate are more perfect than the inanimate, and animals more perfect
than plants, and man than brute animals; and in each of these genera
there are various degrees. For this reason Aristotle, Metaph. viii (Did.
vii, 3), compares the species of things to numbers, which differ in
species by the addition or subtraction of unity. And (De Anima ii, 3) he
compares the various souls to the species of figures, one of which
contains another; as a pentagon contains and exceeds a tetragon. Thus the
intellectual soul contains virtually whatever belongs to the sensitive
soul of brute animals, and to the nutritive souls of plants. Therefore,
as a surface which is of a pentagonal shape, is not tetragonal by one
shape, and pentagonal by another - since a tetragonal shape would be
superfluous as contained in the pentagonal - so neither is Socrates a man
by one soul, and animal by another; but by one and the same soul he is
both animal and man.

Aquin.: SMT FP Q[76] A[3] R.O. 1 Para. 1/1

Reply OBJ 1: The sensitive soul is incorruptible, not by reason of its
being sensitive, but by reason of its being intellectual. When,
therefore, a soul is sensitive only, it is corruptible; but when with
sensibility it has also intellectuality, it is incorruptible. For
although sensibility does not give incorruptibility, yet it cannot
deprive intellectuality of its incorruptibility.

Aquin.: SMT FP Q[76] A[3] R.O. 2 Para. 1/1

Reply OBJ 2: Not forms, but composites, are classified either
generically or specifically. Now man is corruptible like other animals.
And so the difference of corruptible and incorruptible which is on the
part of the forms does not involve a generic difference between man and
the other animals.

Aquin.: SMT FP Q[76] A[3] R.O. 3 Para. 1/1

Reply OBJ 3: The embryo has first of all a soul which is merely
sensitive, and when this is removed, it is supplanted by a more perfect
soul, which is both sensitive and intellectual: as will be shown further
on (Q[118], A[2], ad 2).

Aquin.: SMT FP Q[76] A[3] R.O. 4 Para. 1/1

Reply OBJ 4: We must not consider the diversity of natural things as
proceeding from the various logical notions or intentions, which flow
from our manner of understanding, because reason can apprehend one and
the same thing in various ways. Therefore since, as we have said, the
intellectual soul contains virtually what belongs to the sensitive soul,
and something more, reason can consider separately what belongs to the
power of the sensitive soul, as something imperfect and material. And
because it observes that this is something common to man and to other
animals, it forms thence the notion of the "genus"; while that wherein
the intellectual soul exceeds the sensitive soul, it takes as formal and
perfecting; thence it gathers the "difference" of man.


Aquin.: SMT FP Q[76] A[4] Thes. Para. 1/1

Whether in man there is another form besides the intellectual soul?

Aquin.: SMT FP Q[76] A[4] Obj. 1 Para. 1/1

OBJ 1: It would seem that in man there is another form besides the
intellectual soul. For the Philosopher says (De Anima ii, 1), that "the
soul is the act of a physical body which has life potentially." Therefore
the soul is to the body as a form of matter. But the body has a
substantial form by which it is a body. Therefore some other substantial
form in the body precedes the soul.

Aquin.: SMT FP Q[76] A[4] Obj. 2 Para. 1/1

OBJ 2: Further, man moves himself as every animal does. Now everything
that moves itself is divided into two parts, of which one moves, and the
other is moved, as the Philosopher proves (Phys. viii, 5). But the part
which moves is the soul. Therefore the other part must be such that it
can be moved. But primary matter cannot be moved (Phys. v, 1), since it
is a being only potentially; indeed everything that is moved is a body.
Therefore in man and in every animal there must be another substantial
form, by which the body is constituted.

Aquin.: SMT FP Q[76] A[4] Obj. 3 Para. 1/1

OBJ 3: Further, the order of forms depends on their relation to primary
matter; for "before" and "after" apply by comparison to some beginning.
Therefore if there were not in man some other substantial form besides
the rational soul, and if this were to inhere immediately to primary
matter; it would follow that it ranks among the most imperfect forms
which inher