No More Learning

Reply to Objection 3: Nothing prevents things which coincide in
subject, from being considered under different aspects; therefore they
can belong to various powers of the soul.

Reply to Objection 4: The higher power of itself regards a more
universal formality of the object than the lower power; because the
higher a power is, to a greater number of things does it extend.
Therefore many things are combined in the one formality of the object,
which the higher power considers of itself; while they differ in the
formalities regarded by the lower powers of themselves. Thus it is that
various objects belong to various lower powers; which objects, however,
are subject to one higher power.
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Whether among the powers of the soul there is order?

Objection 1: It would seem that there is no order among the powers of
the soul. For in those things which come under one division, there is
no before and after, but all are naturally simultaneous. But the powers
of the soul are contradistinguished from one another. Therefore there
is no order among them.

Objection 2: Further, the powers of the soul are referred to their
objects and to the soul itself. On the part of the soul, there is not
order among them, because the soul is one. In like manner the objects
are various and dissimilar, as color and sound. Therefore there is no
order among the powers of the soul.

Objection 3: Further, where there is order among powers, we find that
the operation of one depends on the operation of another. But the
action of one power of the soul does not depend on that of another; for
sight can act independently of hearing, and conversely. Therefore there
is no order among the powers of the soul.

On the contrary, The Philosopher (De Anima ii, 3) compares the parts or
powers of the soul to figures. But figures have an order among
themselves. Therefore the powers of the soul have order.

I answer that, Since the soul is one, and the powers are many; and
since a number of things that proceed from one must proceed in a
certain order; there must be some order among the powers of the soul.
Accordingly we may observe a triple order among them, two of which
correspond to the dependence of one power on another; while the third
is taken from the order of the objects. Now the dependence of one power
on another can be taken in two ways; according to the order of nature,
forasmuch as perfect things are by their nature prior to imperfect
things; and according to the order of generation and time; forasmuch as
from being imperfect, a thing comes to be perfect. Thus, according to
the first kind of order among the powers, the intellectual powers are
prior to the sensitive powers; wherefore they direct them and command
them. Likewise the sensitive powers are prior in this order to the
powers of the nutritive soul.

In the second kind of order, it is the other way about. For the powers
of the nutritive soul are prior by way of generation to the powers of
the sensitive soul; for which, therefore, they prepare the body. The
same is to be said of the sensitive powers with regard to the
intellectual. But in the third kind of order, certain sensitive powers
are ordered among themselves, namely, sight, hearing, and smelling. For
the visible naturally comes first; since it is common to higher and
lower bodies. But sound is audible in the air, which is naturally prior
to the mingling of elements, of which smell is the result.

Reply to Objection 1: The species of a given genus are to one another
as before and after, like numbers and figures, if considered in their
nature; although they may be said to be simultaneous, according as they
receive the predication of the common genus.

Reply to Objection 2: This order among the powers of the soul is both
on the part of the soul (which, though it be one according to its
essence, has a certain aptitude to various acts in a certain order) and
on the part of the objects, and furthermore on the part of the acts, as
we have said above.

Reply to Objection 3: This argument is verified as regards those powers
among which order of the third kind exists. Those powers among which
the two other kinds of order exist are such that the action of one
depends on another.
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Whether all the powers of the soul are in the soul as their subject?

Objection 1: It would seem that all the powers of the soul are in the
soul as their subject. For as the powers of the body are to the body;
so are the powers of the soul to the soul. But the body is the subject
of the corporeal powers. Therefore the soul is the subject of the
powers of the soul.

Objection 2: Further, the operations of the powers of the soul are
attributed to the body by reason of the soul; because, as the
Philosopher says (De Anima ii, 2), "The soul is that by which we sense
and understand primarily. " But the natural principles of the operations
of the soul are the powers. Therefore the powers are primarily in the
soul.

Objection 3: Further, Augustine says (Gen. ad lit. xii, 7,24) that the
soul senses certain things, not through the body, in fact, without the
body, as fear and such like; and some things through the body. But if
the sensitive powers were not in the soul alone as their subject, the
soul could not sense anything without the body. Therefore the soul is
the subject of the sensitive powers; and for a similar reason, of all
the other powers.

On the contrary, The Philosopher says (De Somno et Vigilia i) that
"sensation belongs neither to the soul, nor to the body, but to the
composite. " Therefore the sensitive power is in "the composite" as its
subject. Therefore the soul alone is not the subject of all the powers.

I answer that, The subject of operative power is that which is able to
operate, for every accident denominates its proper subject. Now the
same is that which is able to operate, and that which does operate.
Wherefore the "subject of power" is of necessity "the subject of
operation," as again the Philosopher says in the beginning of De Somno
et Vigilia. Now, it is clear from what we have said above ([626]Q[75],
AA[2],3; [627]Q[76], A[1], ad 1), that some operations of the soul are
performed without a corporeal organ, as understanding and will. Hence
the powers of these operations are in the soul as their subject. But
some operations of the soul are performed by means of corporeal organs;
as sight by the eye, and hearing by the ear. And so it is with all the
other operations of the nutritive and sensitive parts. Therefore the
powers which are the principles of these operations have their subject
in the composite, and not in the soul alone.

Reply to Objection 1: All the powers are said to belong to the soul,
not as their subject, but as their principle; because it is by the soul
that the composite has the power to perform such operations.

Reply to Objection 2: All such powers are primarily in the soul, as
compared to the composite; not as in their subject, but as in their
principle.

Reply to Objection 3: Plato's opinion was that sensation is an
operation proper to the soul, just as understanding is. Now in many
things relating to Philosophy Augustine makes use of the opinions of
Plato, not asserting them as true, but relating them. However, as far
as the present question is concerned, when it is said that the soul
senses some things with the body, and some without the body, this can
be taken in two ways. Firstly, the words "with the body or without the
body" may determine the act of sense in its mode of proceeding from the
sentient. Thus the soul senses nothing without the body, because the
action of sensation cannot proceed from the soul except by a corporeal
organ. Secondly, they may be understood as determining the act of sense
on the part of the object sensed. Thus the soul senses some things with
the body, that is, things existing in the body, as when it feels a
wound or something of that sort; while it senses some things without
the body, that is, which do not exist in the body, but only in the
apprehension of the soul, as when it feels sad or joyful on hearing
something.
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Whether the powers of the soul flow from its essence?

Objection 1: It would seem that the powers of the soul do not flow from
its essence. For different things do not proceed from one simple thing.
But the essence of the soul is one and simple. Since, therefore, the
powers of the soul are many and various, they cannot proceed from its
essence.

Objection 2: Further, that from which a thing proceeds is its cause.
But the essence of the soul cannot be said to be the cause of the
powers; as is clear if one considers the different kinds of causes.
Therefore the powers of the soul do not flow from its essence.

Objection 3: Further, emanation involves some sort of movement. But
nothing is moved by itself, as the Philosopher proves (Phys. vii, 1,2);
except, perhaps, by reason of a part of itself, as an animal is said to
be moved by itself, because one part thereof moves and another is
moved. Neither is the soul moved, as the Philosopher proves (De Anima
i, 4). Therefore the soul does not produce its powers within itself.

On the contrary, The powers of the soul are its natural properties. But
the subject is the cause of its proper accidents; whence also it is
included in the definition of accident, as is clear from Metaph. vii
(Did. vi, 4). Therefore the powers of the soul proceed from its essence
as their cause.

I answer that, The substantial and the accidental form partly agree and
partly differ. They agree in this, that each is an act; and that by
each of them something is after a manner actual. They differ, however,
in two respects. First, because the substantial form makes a thing to
exist absolutely, and its subject is something purely potential. But
the accidental form does not make a thing to exist absolutely but to be
such, or so great, or in some particular condition; for its subject is
an actual being. Hence it is clear that actuality is observed in the
substantial form prior to its being observed in the subject: and since
that which is first in a genus is the cause in that genus, the
substantial form causes existence in its subject. On the other hand,
actuality is observed in the subject of the accidental form prior to
its being observed in the accidental form; wherefore the actuality of
the accidental form is caused by the actuality of the subject. So the
subject, forasmuch as it is in potentiality, is receptive of the
accidental form: but forasmuch as it is in act, it produces it. This I
say of the proper and "per se" accident; for with regard to the
extraneous accident, the subject is receptive only, the accident being
caused by an extrinsic agent. Secondly, substantial and accidental
forms differ, because, since that which is the less principal exists
for the sake of that which is the more principal, matter therefore
exists on account of the substantial form; while on the contrary, the
accidental form exists on account of the completeness of the subject.

Now it is clear, from what has been said [628](A[5]), that either the
subject of the soul's powers is the soul itself alone, which can be the
subject of an accident, forasmuch as it has something of potentiality,
as we have said above (A[1], ad 6); or else this subject is the
composite. Now the composite is actual by the soul. Whence it is clear
that all the powers of the soul, whether their subject be the soul
alone, or the composite, flow from the essence of the soul, as from
their principle; because it has already been said that the accident is
caused by the subject according as it is actual, and is received into
it according as it is in potentiality.

Reply to Objection 1: From one simple thing many things may proceed
naturally, in a certain order; or again if there be diversity of
recipients. Thus, from the one essence of the soul many and various
powers proceed; both because order exists among these powers; and also
by reason of the diversity of the corporeal organs.

Reply to Objection 2: The subject is both the final cause, and in a way
the active cause, of its proper accident. It is also as it were the
material cause, inasmuch as it is receptive of the accident. From this
we may gather that the essence of the soul is the cause of all its
powers, as their end, and as their active principle; and of some as
receptive thereof.

Reply to Objection 3: The emanation of proper accidents from their
subject is not by way of transmutation, but by a certain natural
resultance; thus one thing results naturally from another, as color
from light.
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Whether one power of the soul arises from another?

Objection 1: It would seem that one power of the soul does not arise
from another. For if several things arise together, one of them does
not arise from another. But all the powers of the soul are created at
the same time with the soul. Therefore one of them does not arise from
another.

Objection 2: Further, the power of the soul arises from the soul as an
accident from the subject. But one power of the soul cannot be the
subject of another; because nothing is the accident of an accident.
Therefore one power does not arise from another.

Objection 3: Further, one opposite does not arise from the other
opposite; but everything arises from that which is like it in species.
Now the powers of the soul are oppositely divided, as various species.
Therefore one of them does not proceed from another.

On the contrary, Powers are known by their actions. But the action of
one power is caused by the action of another power, as the action of
the imagination by the action of the senses. Therefore one power of the
soul is caused by another.

I answer that, In those things which proceed from one according to a
natural order, as the first is the cause of all, so that which is
nearer to the first is, in a way, the cause of those which are more
remote. Now it has been shown above [629](A[4]) that among the powers
of the soul there are several kinds of order. Therefore one power of
the soul proceeds from the essence of the soul by the medium of
another. But since the essence of the soul is compared to the powers
both as a principle active and final, and as a receptive principle,
either separately by itself, or together with the body; and since the
agent and the end are more perfect, while the receptive principle, as
such, is less perfect; it follows that those powers of the soul which
precede the others, in the order of perfection and nature, are the
principles of the others, after the manner of the end and active
principle. For we see that the senses are for the sake of the
intelligence, and not the other way about. The senses, moreover, are a
certain imperfect participation of the intelligence; wherefore,
according to their natural origin, they proceed from the intelligence
as the imperfect from the perfect. But considered as receptive
principles, the more perfect powers are principles with regard to the
others; thus the soul, according as it has the sensitive power, is
considered as the subject, and as something material with regard to the
intelligence. On this account, the more imperfect powers precede the
others in the order of generation, for the animal is generated before
the man.

Reply to Objection 1: As the power of the soul flows from the essence,
not by a transmutation, but by a certain natural resultance, and is
simultaneous with the soul, so is it the case with one power as regards
another.

Reply to Objection 2: An accident cannot of itself be the subject of an
accident; but one accident is received prior to another into substance,
as quantity prior to quality. In this sense one accident is said to be
the subject of another; as surface is of color, inasmuch as substance
receives an accident through the means of another. The same thing may
be said of the powers of the soul.

Reply to Objection 3: The powers of the soul are opposed to one
another, as perfect and imperfect; as also are the species of numbers
and figures. But this opposition does not prevent the origin of one
from another, because imperfect things naturally proceed from perfect
things.
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Whether all the powers remain in the soul when separated from the body?

Objection 1: It would seem that all the powers of the soul remain in
the soul separated from the body. For we read in the book De Spiritu et
Anima that "the soul withdraws from the body, taking with itself sense
and imagination, reason and intelligence, concupiscibility and
irascibility. "

Objection 2: Further, the powers of the soul are its natural
properties. But properties are always in that to which they belong; and
are never separated from it. Therefore the powers of the soul are in it
even after death.

Objection 3: Further, the powers even of the sensitive soul are not
weakened when the body becomes weak; because, as the Philosopher says
(De Anima i, 4), "If an old man were given the eye of a young man, he
would see even as well as a young man. " But weakness is the road to
corruption. Therefore the powers of the soul are not corrupted when the
body is corrupted, but remain in the separated soul.

Objection 4: Further, memory is a power of the sensitive soul, as the
Philosopher proves (De Memor. et Remin. 1). But memory remains in the
separated soul; for it was said to the rich glutton whose soul was in
hell: "Remember that thou didst receive good things during thy
lifetime" (Lk. 16:25). Therefore memory remains in the separated soul;
and consequently the other powers of the sensitive part.

Objection 5: Further, joy and sorrow are in the concupiscible part,
which is a power of the sensitive soul. But it is clear that separate
souls grieve or rejoice at the pains or rewards which they receive.
Therefore the concupiscible power remains in the separate soul.

Objection 6: Further, Augustine says (Gen. ad lit. xii, 32) that, as
the soul, when the body lies senseless, yet not quite dead, sees some
things by imaginary vision; so also when by death the soul is quite
separate from the body. But the imagination is a power of the sensitive
part. Therefore the power of the sensitive part remains in the separate
soul; and consequently all the other powers.

On the contrary, It is said (De Eccl. Dogm. xix) that "of two
substances only does man consist; the soul with its reason, and the
body with its senses. " Therefore the body being dead, the sensitive
powers do not remain.

I answer that, As we have said already ([630]AA[5],6,7), all the powers
of the soul belong to the soul alone as their principle. But some
powers belong to the soul alone as their subject; as the intelligence
and the will. These powers must remain in the soul, after the
destruction of the body. But other powers are subjected in the
composite; as all the powers of the sensitive and nutritive parts. Now
accidents cannot remain after the destruction of the subject.
Wherefore, the composite being destroyed, such powers do not remain
actually; but they remain virtually in the soul, as in their principle
or root.

So it is false that, as some say, these powers remain in the soul even
after the corruption of the body. It is much more false that, as they
say also, the acts of these powers remain in the separate soul; because
these powers have no act apart from the corporeal organ.

Reply to Objection 1: That book has no authority, and so what is there
written can be despised with the same facility as it was said; although
we may say that the soul takes with itself these powers, not actually
but virtually.

Reply to Objection 2: These powers, which we say do not actually remain
in the separate soul, are not the properties of the soul alone, but of
the composite.

Reply to Objection 3: These powers are said not to be weakened when the
body becomes weak, because the soul remains unchangeable, and is the
virtual principle of these powers.

Reply to Objection 4: The recollection spoken of there is to be taken
in the same way as Augustine (De Trin. x, 11; xiv, 7) places memory in
the mind; not as a part of the sensitive soul.

Reply to Objection 5: In the separate soul, sorrow and joy are not in
the sensitive, but in the intellectual appetite, as in the angels.

Reply to Objection 6: Augustine in that passage is speaking as
inquiring, not as asserting. Wherefore he retracted some things which
he had said there (Retrac. ii, 24).
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OF THE SPECIFIC POWERS OF THE SOUL (FOUR ARTICLES)

We next treat of the powers of the soul specifically. The theologian,
however, has only to inquire specifically concerning the intellectual
and appetitive powers, in which the virtues reside. And since the
knowledge of these powers depends to a certain extent on the other
powers, our consideration of the powers of the soul taken specifically
will be divided into three parts: first, we shall consider those powers
which are a preamble to the intellect; secondly, the intellectual
powers; thirdly, the appetitive powers.

Under the first head there are four points of inquiry:

(1) The powers of the soul considered generally;

(2) The various species of the vegetative part;

(3) The exterior senses;

(4) The interior senses.
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Whether there are to be distinguished five genera of powers in the soul?

Objection 1: It would seem that there are not to be distinguished five
genera of powers in the soul---namely, vegetative, sensitive,
appetitive, locomotive, and intellectual. For the powers of the soul
are called its parts. But only three parts of the soul are commonly
assigned---namely, the vegetative soul, the sensitive soul, and the
rational soul. Therefore there are only three genera of powers in the
soul, and not five.

Objection 2: Further, the powers of the soul are the principles of its
vital operations. Now, in four ways is a thing said to live. For the
Philosopher says (De Anima ii, 2): "In several ways a thing is said to
live, and even if only one of these is present, the thing is said to
live; as intellect and sense, local movement and rest, and lastly,
movement of decrease and increase due to nourishment. " Therefore there
are only four genera of powers of the soul, as the appetitive is
excluded.

Objection 3: Further, a special kind of soul ought not to be assigned
as regards what is common to all the powers. Now desire is common to
each power of the soul. For sight desires an appropriate visible
object; whence we read (Ecclus. 40:22): "The eye desireth favor and
beauty, but more than these green sown fields. " In the same way every
other power desires its appropriate object. Therefore the appetitive
power should not be made a special genus of the powers of the soul.

Objection 4: Further, the moving principle in animals is sense,
intellect or appetite, as the Philosopher says (De Anima iii, 10).
Therefore the motive power should not be added to the above as a
special genus of soul.

On the contrary, The Philosopher says (De Anima ii, 3), "The powers are
the vegetative, the sensitive, the appetitive, the locomotion, and the
intellectual. "

I answer that, There are five genera of powers of the soul, as above
numbered. Of these, three are called souls, and four are called modes
of living.
The reason of this diversity lies in the various souls being
distinguished accordingly as the operation of the soul transcends the
operation of the corporeal nature in various ways; for the whole
corporeal nature is subject to the soul, and is related to it as its
matter and instrument. There exists, therefore, an operation of the
soul which so far exceeds the corporeal nature that it is not even
performed by any corporeal organ; and such is the operation of the
"rational soul. " Below this, there is another operation of the soul,
which is indeed performed through a corporeal organ, but not through a
corporeal quality, and this is the operation of the "sensitive soul";
for though hot and cold, wet and dry, and other such corporeal
qualities are required for the work of the senses, yet they are not
required in such a way that the operation of the senses takes place by
virtue of such qualities; but only for the proper disposition of the
organ. The lowest of the operations of the soul is that which is
performed by a corporeal organ, and by virtue of a corporeal quality.
Yet this transcends the operation of the corporeal nature; because the
movements of bodies are caused by an extrinsic principle, while these
operations are from an intrinsic principle; for this is common to all
the operations of the soul; since every animate thing, in some way,
moves itself. Such is the operation of the "vegetative soul"; for
digestion, and what follows, is caused instrumentally by the action of
heat, as the Philosopher says (De Anima ii, 4).

Now the powers of the soul are distinguished generically by their
objects. For the higher a power is, the more universal is the object to
which it extends, as we have said above ([631]Q[77], A[3], ad 4). But
the object of the soul's operation may be considered in a triple order.
For in the soul there is a power the object of which is only the body
that is united to that soul; the powers of this genus are called
"vegetative" for the vegetative power acts only on the body to which
the soul is united. There is another genus in the powers of the soul,
which genus regards a more universal object---namely, every sensible
body, not only the body to which the soul is united. And there is yet
another genus in the powers of the soul, which genus regards a still
more universal object---namely, not only the sensible body, but all
being in universal. Wherefore it is evident that the latter two genera
of the soul's powers have an operation in regard not merely to that
which is united to them, but also to something extrinsic. Now, since
whatever operates must in some way be united to the object about which
it operates, it follows of necessity that this something extrinsic,
which is the object of the soul's operation, must be related to the
soul in a twofold manner. First, inasmuch as this something extrinsic
has a natural aptitude to be united to the soul, and to be by its
likeness in the soul. In this way there are two kinds of powers
---namely, the "sensitive" in regard to the less common object---the
sensible body; and the "intellectual," in regard to the most common
object---universal being. Secondly, forasmuch as the soul itself has an
inclination and tendency to the something extrinsic. And in this way
there are again two kinds of powers in the soul: one---the
"appetitive"---in respect of which the soul is referred to something
extrinsic as to an end, which is first in the intention; the
other---the "locomotive" power---in respect of which the soul is
referred to something extrinsic as to the term of its operation and
movement; for every animal is moved for the purpose of realizing its
desires and intentions.

The modes of living are distinguished according to the degrees of
living things. There are some living things in which there exists only
vegetative power, as the plants. There are others in which with the
vegetative there exists also the sensitive, but not the locomotive
power; such as immovable animals, as shellfish. There are others which
besides this have locomotive powers, as perfect animals, which require
many things for their life, and consequently movement to seek
necessaries of life from a distance. And there are some living things
which with these have intellectual power---namely, men. But the
appetitive power does not constitute a degree of living things; because
wherever there is sense there is also appetite (De Anima ii, 3).

Thus the first two objectives are hereby solved.

Reply to Objection 3: The "natural appetite" is that inclination which
each thing has, of its own nature, for something; wherefore by its
natural appetite each power desires something suitable to itself. But
the "animal appetite" results from the form apprehended; this sort of
appetite requires a special power of the soul---mere apprehension does
not suffice. For a thing is desired as it exists in its own nature,
whereas in the apprehensive power it exists not according to its own
nature, but according to its likeness. Whence it is clear that sight
desires naturally a visible object for the purpose of its act
only---namely, for the purpose of seeing; but the animal by the
appetitive power desires the thing seen, not merely for the purpose of
seeing it, but also for other purposes. But if the soul did not require
things perceived by the senses, except on account of the actions of the
senses, that is, for the purpose of sensing them; there would be no
need for a special genus of appetitive powers, since the natural
appetite of the powers would suffice.

Reply to Objection 4: Although sense and appetite are principles of
movement in perfect animals, yet sense and appetite, as such, are not
sufficient to cause movement, unless another power be added to them;
for immovable animals have sense and appetite, and yet they have not
the power of motion. Now this motive power is not only in the appetite
and sense as commanding the movement, but also in the parts of the
body, to make them obey the appetite of the soul which moves them. Of
this we have a sign in the fact that when the members are deprived of
their natural disposition, they do not move in obedience to the
appetite.
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Whether the parts of the vegetative soul are fittingly described as the
nutritive, augmentative, and generative?

Objection 1: It would seem that the parts of the vegetative soul are
not fittingly described---namely, the nutritive, augmentative, and
generative. For these are called "natural" forces. But the powers of
the soul are above the natural forces. Therefore we should not class
the above forces as powers of the soul.

Objection 2: Further, we should not assign a particular power of the
soul to that which is common to living and non-living things. But
generation is common to all things that can be generated and corrupted,
whether living or not living. Therefore the generative force should not
be classed as a power of the soul.

Objection 3: Further, the soul is more powerful than the body. But the
body by the same force gives species and quantity; much more,
therefore, does the soul. Therefore the augmentative power of the soul
is not distinct from the generative power.

Objection 4: Further, everything is preserved in being by that whereby
it exists. But the generative power is that whereby a living thing
exists. Therefore by the same power the living thing is preserved. Now
the nutritive force is directed to the preservation of the living thing
(De Anima ii, 4), being "a power which is capable of preserving
whatever receives it. " Therefore we should not distinguish the
nutritive power from the generative.

On the contrary, The Philosopher says (De Anima ii, 2,4) that the
operations of this soul are "generation, the use of food," and (cf. De
Anima iii, 9) "growth. "

I answer that, The vegetative part has three powers. For the vegetative
part, as we have said [632](A[1]), has for its object the body itself,
living by the soul; for which body a triple operation of the soul is
required. One is whereby it acquires existence, and to this is directed
the "generative" power. Another is whereby the living body acquires its
due quantity; to this is directed the "augmentative" power. Another is
whereby the body of a living thing is preserved in its existence and in
its due quantity; to this is directed the "nutritive" power.

We must, however, observe a difference among these powers. The
nutritive and the augmentative have their effect where they exist,
since the body itself united to the soul grows and is preserved by the
augmentative and nutritive powers which exist in one and the same soul.
But the generative power has its effect, not in one and the same body
but in another; for a thing cannot generate itself. Therefore the
generative power, in a way, approaches to the dignity of the sensitive
soul, which has an operation extending to extrinsic things, although in
a more excellent and more universal manner; for that which is highest
in an inferior nature approaches to that which is lowest in the higher
nature, as is made clear by Dionysius (Div. Nom. vii). Therefore, of
these three powers, the generative has the greater finality, nobility,
and perfection, as the Philosopher says (De Anima ii, 4), for it
belongs to a thing which is already perfect to "produce another like
unto itself. " And the generative power is served by the augmentative
and nutritive powers; and the augmentative power by the nutritive.

Reply to Objection 1: Such forces are called natural, both because they
produce an effect like that of nature, which also gives existence,
quantity and preservation (although the above forces accomplish these
things in a more perfect way); and because those forces perform their
actions instrumentally, through the active and passive qualities, which
are the principles of natural actions.

Reply to Objection 2: Generation of inanimate things is entirely from
an extrinsic source; whereas the generation of living things is in a
higher way, through something in the living thing itself, which is the
semen containing the principle productive of the body. Therefore there
must be in the living thing a power that prepares this semen; and this
is the generative power.

Reply to Objection 3: Since the generation of living things is from a
semen, it is necessary that in the beginning an animal of small size be
generated. For this reason it must have a power in the soul, whereby it
is brought to its appropriate size. But the inanimate body is generated
from determinate matter by an extrinsic agent; therefore it receives at
once its nature and its quantity, according to the condition of the
matter.

Reply to Objection 4: As we have said above [633](A[1]), the operation
of the vegetative principle is performed by means of heat, the property
of which is to consume humidity. Therefore, in order to restore the
humidity thus lost, the nutritive power is required, whereby the food
is changed into the substance of the body. This is also necessary for
the action of the augmentative and generative powers.
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Whether the five exterior senses are properly distinguished?

Objection 1: It would seem inaccurate to distinguish five exterior
senses. But there are many kinds of accidents. Therefore, as powers are
distinguished by their objects, it seems that the senses are multiplied
according to the number of the kinds of accidents.

Objection 2: Further, magnitude and shape, and other things which are
called "common sensibles," are "not sensibles by accident," but are
contradistinguished from them by the Philosopher (De Anima ii, 6). Now
the diversity of objects, as such, diversifies the powers. Since,
therefore, magnitude and shape are further from color than sound is, it
seems that there is much more need for another sensitive power than can
grasp magnitude or shape than for that which grasps color or sound.

Objection 3: Further, one sense regards one contrariety; as sight
regards white and black. But the sense of touch grasps several
contraries; such as hot or cold, damp or dry, and suchlike. Therefore
it is not a single sense but several. Therefore there are more than
five senses.

Objection 4: Further, a species is not divided against its genus. But
taste is a kind of touch. Therefore it should not be classed as a
distinct sense of touch.

On the contrary, The Philosopher says (De Anima iii, 1): "There is no
other besides the five senses. "

I answer that, The reason of the distinction and number of the senses
has been assigned by some to the organs in which one or other of the
elements preponderate, as water, air, or the like. By others it has
been assigned to the medium, which is either in conjunction or
extrinsic and is either water or air, or such like. Others have
ascribed it to the various natures of the sensible qualities, according
as such quality belongs to a simple body or results from complexity.
But none of these explanations is apt. For the powers are not for the
organs, but the organs for the powers; wherefore there are not various
powers for the reason that there are various organs; on the contrary,
for this has nature provided a variety of organs, that they might be
adapted to various powers. In the same way nature provided various
mediums for the various senses, according to the convenience of the
acts of the powers. And to be cognizant of the natures of sensible
qualities does not pertain to the senses, but to the intellect.

The reason of the number and distinction of the exterior senses must
therefore be ascribed to that which belongs to the senses properly and
"per se. " Now, sense is a passive power, and is naturally immuted by
the exterior sensible. Wherefore the exterior cause of such immutation
is what is "per se" perceived by the sense, and according to the
diversity of that exterior cause are the sensitive powers diversified.

Now, immutation is of two kinds, one natural, the other spiritual.
Natural immutation takes place by the form of the immuter being
received according to its natural existence, into the thing immuted, as
heat is received into the thing heated. Whereas spiritual immutation
takes place by the form of the immuter being received, according to a
spiritual mode of existence, into the thing immuted, as the form of
color is received into the pupil which does not thereby become colored.
Now, for the operation of the senses, a spiritual immutation is
required, whereby an intention of the sensible form is effected in the
sensile organ. Otherwise, if a natural immutation alone sufficed for
the sense's action, all natural bodies would feel when they undergo
alteration.

But in some senses we find spiritual immutation only, as in "sight"
while in others we find not only spiritual but also a natural
immutation; either on the part of the object only, or likewise on the
part of the organ. On the part of the object we find natural
immutation, as to place, in sound which is the object of "hearing"; for
sound is caused by percussion and commotion of air: and we find natural
immutation by alteration, in odor which is the object of "smelling";
for in order to exhale an odor, a body must be in a measure affected by
heat. On the part of an organ, natural immutation takes place in
"touch" and "taste"; for the hand that touches something hot becomes
hot, while the tongue is moistened by the humidity of the flavored
morsel. But the organs of smelling and hearing are not affected in
their respective operations by any natural immutation unless
indirectly.

Now, the sight, which is without natural immutation either in its organ
or in its object, is the most spiritual, the most perfect, and the most
universal of all the senses. After this comes the hearing and then the
smell, which require a natural immutation on the part of the object;
while local motion is more perfect than, and naturally prior to, the
motion of alteration, as the Philosopher proves (Phys. viii, 7). Touch
and taste are the most material of all: of the distinction of which we
shall speak later on (ad 3,4). Hence it is that the three other senses
are not exercised through a medium united to them, to obviate any
natural immutation in their organ; as happens as regards these two
senses.

Reply to Objection 1: Not every accident has in itself a power of
immutation but only qualities of the third species, which are the
principles of alteration: therefore only suchlike qualities are the
objects of the senses; because "the senses are affected by the same
things whereby inanimate bodies are affected," as stated in Phys. vii,
2.

Reply to Objection 2: Size, shape, and the like, which are called
"common sensibles," are midway between "accidental sensibles" and
"proper sensibles," which are the objects of the senses. For the proper
sensibles first, and of their very nature, affect the senses; since
they are qualities that cause alteration. But the common sensibles are
all reducible to quantity. As to size and number, it is clear that they
are species of quantity. Shape is a quality about quantity. Shape is a
quality about quantity, since the notion of shape consists of fixing
the bounds of magnitude. Movement and rest are sensed according as the
subject is affected in one or more ways in the magnitude of the subject
or of its local distance, as in the movement of growth or of
locomotion, or again, according as it is affected in some sensible
qualities, as in the movement of alteration; and thus to sense movement
and rest is, in a way, to sense one thing and many. Now quantity is the
proximate subject of the qualities that cause alteration, as surface is
of color. Therefore the common sensibles do not move the senses first
and of their own nature, but by reason of the sensible quality; as the
surface by reason of color. Yet they are not accidental sensibles, for
they produce a certain variety in the immutation of the senses. For
sense is immuted differently by a large and by a small surface: since
whiteness itself is said to be great or small, and therefore it is
divided according to its proper subject.

Reply to Objection 3: As the Philosopher seems to say (De Anima ii,
11), the sense of touch is generically one, but is divided into several
specific senses, and for this reason it extends to various
contrarieties; which senses, however, are not separate from one another
in their organ, but are spread throughout the whole body, so that their
distinction is not evident. But taste, which perceives the sweet and
the bitter, accompanies touch in the tongue, but not in the whole body;
so it is easily distinguished from touch. We might also say that all
those contrarieties agree, each in some proximate genus, and all in a
common genus, which is the common and formal object of touch. Such
common genus is, however, unnamed, just as the proximate genus of hot
and cold is unnamed.

Reply to Objection 4: The sense of taste, according to a saying of the
Philosopher (De Anima ii, 9), is a kind of touch existing in the tongue
only. It is not distinct from touch in general, but only from the
species of touch distributed in the body. But if touch is one sense
only, on account of the common formality of its object: we must say
that taste is distinguished from touch by reason of a different
formality of immutation. For touch involves a natural, and not only a
spiritual, immutation in its organ, by reason of the quality which is
its proper object. But the organ of taste is not necessarily immuted by
a natural immutation by reason of the quality which is its proper
object, so that the tongue itself becomes sweet and bitter: but by
reason of a quality which is a preamble to, and on which is based, the
flavor, which quality is moisture, the object of touch.
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Whether the interior senses are suitably distinguished?

Objection 1: It would seem that the interior senses are not suitably
distinguished. For the common is not divided against the proper.
Therefore the common sense should not be numbered among the interior
sensitive powers, in addition to the proper exterior senses.

Objection 2: Further, there is no need to assign an interior power of
apprehension when the proper and exterior sense suffices. But the
proper and exterior senses suffice for us to judge of sensible things;
for each sense judges of its proper object. In like manner they seem to
suffice for the perception of their own actions; for since the action
of the sense is, in a way, between the power and its object, it seems
that sight must be much more able to perceive its own vision, as being
nearer to it, than the color; and in like manner with the other senses.
Therefore for this there is no need to assign an interior power, called
the common sense.

Objection 3: Further, according to the Philosopher (De Memor. et Remin.
i), the imagination and the memory are passions of the "first
sensitive. " But passion is not divided against its subject. Therefore
memory and imagination should not be assigned as powers distinct from
the senses.

Objection 4: Further, the intellect depends on the senses less than any
power of the sensitive part. But the intellect knows nothing but what
it receives from the senses; whence we read (Poster. i, 8), that "those
who lack one sense lack one kind of knowledge. " Therefore much less
should we assign to the sensitive part a power, which they call the
"estimative" power, for the perception of intentions which the sense
does not perceive.

Objection 5: Further, the action of the cogitative power, which
consists in comparing, adding and dividing, and the action of the
reminiscence, which consists in the use of a kind of syllogism for the
sake of inquiry, is not less distant from the actions of the estimative
and memorative powers, than the action of the estimative is from the
action of the imagination. Therefore either we must add the cognitive
and reminiscitive to the estimative and memorative powers, or the
estimative and memorative powers should not be made distinct from the
imagination.

Objection 6: Further, Augustine (Gen. ad lit. xii, 6,7,24) describes
three kinds of vision; namely, corporeal, which is the action of the
sense; spiritual, which is an action of the imagination or phantasy;
and intellectual, which is an action of the intellect. Therefore there
is no interior power between the sense and intellect, besides the
imagination.

On the contrary, Avicenna (De Anima iv, 1) assigns five interior
sensitive powers; namely, "common sense, phantasy, imagination, and the
estimative and memorative powers. "

I answer that, As nature does not fail in necessary things, there must
needs be as many actions of the sensitive soul as may suffice for the
life of a perfect animal. If any of these actions cannot be reduced to
the same one principle, they must be assigned to diverse powers; since
a power of the soul is nothing else than the proximate principle of the
soul's operation.

Now we must observe that for the life of a perfect animal, the animal
should apprehend a thing not only at the actual time of sensation, but
also when it is absent. Otherwise, since animal motion and action
follow apprehension, an animal would not be moved to seek something
absent: the contrary of which we may observe specially in perfect
animals, which are moved by progression, for they are moved towards
something apprehended and absent. Therefore an animal through the
sensitive soul must not only receive the species of sensible things,
when it is actually affected by them, but it must also retain and
preserve them. Now to receive and retain are, in corporeal things,
reduced to diverse principles; for moist things are apt to receive, but
retain with difficulty, while it is the reverse with dry things.
Wherefore, since the sensitive power is the act of a corporeal organ,
it follows that the power which receives the species of sensible things
must be distinct from the power which preserves them.

Again we must observe that if an animal were moved by pleasing and
disagreeable things only as affecting the sense, there would be no need
to suppose that an animal has a power besides the apprehension of those
forms which the senses perceive, and in which the animal takes
pleasure, or from which it shrinks with horror. But the animal needs to
seek or to avoid certain things, not only because they are pleasing or
otherwise to the senses, but also on account of other advantages and
uses, or disadvantages: just as the sheep runs away when it sees a
wolf, not on account of its color or shape, but as a natural enemy: and
again a bird gathers together straws, not because they are pleasant to
the sense, but because they are useful for building its nest. Animals,
therefore, need to perceive such intentions, which the exterior sense
does not perceive. And some distinct principle is necessary for this;
since the perception of sensible forms comes by an immutation caused by
the sensible, which is not the case with the perception of those
intentions.

Thus, therefore, for the reception of sensible forms, the "proper
sense" and the "common sense" are appointed, and of their distinction
we shall speak farther on (ad 1,2). But for the retention and
preservation of these forms, the "phantasy" or "imagination" is
appointed; which are the same, for phantasy or imagination is as it
were a storehouse of forms received through the senses. Furthermore,
for the apprehension of intentions which are not received through the
senses, the "estimative" power is appointed: and for the preservation
thereof, the "memorative" power, which is a storehouse of such-like
intentions. A sign of which we have in the fact that the principle of
memory in animals is found in some such intention, for instance, that
something is harmful or otherwise. And the very formality of the past,
which memory observes, is to be reckoned among these intentions.

Now, we must observe that as to sensible forms there is no difference
between man and other animals; for they are similarly immuted by the
extrinsic sensible. But there is a difference as to the above
intentions: for other animals perceive these intentions only by some
natural instinct, while man perceives them by means of coalition of
ideas. Therefore the power by which in other animals is called the
natural estimative, in man is called the "cogitative," which by some
sort of collation discovers these intentions. Wherefore it is also
called the "particular reason," to which medical men assign a certain
particular organ, namely, the middle part of the head: for it compares
individual intentions, just as the intellectual reason compares
universal intentions. As to the memorative power, man has not only
memory, as other animals have in the sudden recollection of the past;
but also "reminiscence" by syllogistically, as it were, seeking for a
recollection of the past by the application of individual intentions.
Avicenna, however, assigns between the estimative and the imaginative,
a fifth power, which combines and divides imaginary forms: as when from
the imaginary form of gold, and imaginary form of a mountain, we
compose the one form of a golden mountain, which we have never seen.
But this operation is not to be found in animals other than man, in
whom the imaginative power suffices thereto. To man also does Averroes
attribute this action in his book De sensu et sensibilibus (viii). So
there is no need to assign more than four interior powers of the
sensitive part---namely, the common sense, the imagination, and the
estimative and memorative powers.

Reply to Objection 1: The interior sense is called "common" not by
predication, as if it were a genus; but as the common root and
principle of the exterior senses.

Reply to Objection 2: The proper sense judges of the proper sensible by
discerning it from other things which come under the same sense; for
instance, by discerning white from black or green. But neither sight
nor taste can discern white from sweet: because what discerns between
two things must know both. Wherefore the discerning judgment must be
assigned to the common sense; to which, as to a common term, all
apprehensions of the senses must be referred: and by which, again, all
the intentions of the senses are perceived; as when someone sees that
he sees. For this cannot be done by the proper sense, which only knows
the form of the sensible by which it is immuted, in which immutation
the action of sight is completed, and from immutation follows another
in the common sense which perceives the act of vision.

Reply to Objection 3: As one power arises from the soul by means of
another, as we have seen above ([634]Q[77], A[7]), so also the soul is
the subject of one power through another. In this way the imagination
and the memory are called passions of the "first sensitive. "

Reply to Objection 4: Although the operation of the intellect has its
origin in the senses: yet, in the thing apprehended through the senses,
the intellect knows many things which the senses cannot perceive. In
like manner does the estimative power, though in a less perfect manner.

Reply to Objection 5: The cogitative and memorative powers in man owe
their excellence not to that which is proper to the sensitive part; but
to a certain affinity and proximity to the universal reason, which, so
to speak, overflows into them. Therefore they are not distinct powers,
but the same, yet more perfect than in other animals.

Reply to Objection 6: Augustine calls that vision spiritual which is
effected by the images of bodies in the absence of bodies. Whence it is
clear that it is common to all interior apprehensions.
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OF THE INTELLECTUAL POWERS (THIRTEEN ARTICLES)

The next question concerns the intellectual powers, under which head
there are thirteen points of inquiry:

(1) Whether the intellect is a power of the soul, or its essence?

(2) If it be a power, whether it is a passive power?

(3) If it is a passive power, whether there is an active intellect?

(4) Whether it is something in the soul?

(5) Whether the active intellect is one in all?