No More Learning

But all bodies are mobile and changeable.
Therefore the soul cannot know bodies through the intellect.

On the contrary, Science is in the intellect. If, therefore, the
intellect does not know bodies, it follows that there is no science of
bodies; and thus perishes natural science, which treats of mobile
bodies.

I answer that, It should be said in order to elucidate this question,
that the early philosophers, who inquired into the natures of things,
thought there was nothing in the world save bodies. And because they
observed that all bodies are mobile, and considered them to be ever in
a state of flux, they were of opinion that we can have no certain
knowledge of the true nature of things. For what is in a continual
state of flux, cannot be grasped with any degree of certitude, for it
passes away ere the mind can form a judgment thereon: according to the
saying of Heraclitus, that "it is not possible twice to touch a drop of
water in a passing torrent," as the Philosopher relates (Metaph. iv,
Did. iii, 5).

After these came Plato, who, wishing to save the certitude of our
knowledge of truth through the intellect, maintained that, besides
these things corporeal, there is another genus of beings, separate from
matter and movement, which beings he called "species" or "ideas," by
participation of which each one of these singular and sensible things
is said to be either a man, or a horse, or the like. Wherefore he said
that sciences and definitions, and whatever appertains to the act of
the intellect, are not referred to these sensible bodies, but to those
beings immaterial and separate: so that according to this the soul does
not understand these corporeal things, but the separate species
thereof.

Now this may be shown to be false for two reasons. First, because,
since those species are immaterial and immovable, knowledge of movement
and matter would be excluded from science (which knowledge is proper to
natural science), and likewise all demonstration through moving and
material causes. Secondly, because it seems ridiculous, when we seek
for knowledge of things which are to us manifest, to introduce other
beings, which cannot be the substance of those others, since they
differ from them essentially: so that granted that we have a knowledge
of those separate substances, we cannot for that reason claim to form a
judgment concerning these sensible things.

Now it seems that Plato strayed from the truth because, having observed
that all knowledge takes place through some kind of similitude, he
thought that the form of the thing known must of necessity be in the
knower in the same manner as in the thing known. Then he observed that
the form of the thing understood is in the intellect under conditions
of universality, immateriality, and immobility: which is apparent from
the very operation of the intellect, whose act of understanding has a
universal extension, and is subject to a certain amount of necessity:
for the mode of action corresponds to the mode of the agent's form.
Wherefore he concluded that the things which we understand must have in
themselves an existence under the same conditions of immateriality and
immobility.

But there is no necessity for this. For even in sensible things it is
to be observed that the form is otherwise in one sensible than in
another: for instance, whiteness may be of great intensity in one, and
of a less intensity in another: in one we find whiteness with
sweetness, in another without sweetness. In the same way the sensible
form is conditioned differently in the thing which is external to the
soul, and in the senses which receive the forms of sensible things
without receiving matter, such as the color of gold without receiving
gold. So also the intellect, according to its own mode, receives under
conditions of immateriality and immobility, the species of material and
mobile bodies: for the received is in the receiver according to the
mode of the receiver. We must conclude, therefore, that through the
intellect the soul knows bodies by a knowledge which is immaterial,
universal, and necessary.

Reply to Objection 1: These words of Augustine are to be understood as
referring to the medium of intellectual knowledge, and not to its
object. For the intellect knows bodies by understanding them, not
indeed through bodies, nor through material and corporeal species; but
through immaterial and intelligible species, which can be in the soul
by their own essence.

Reply to Objection 2: As Augustine says (De Civ. Dei xxii, 29), it is
not correct to say that as the sense knows only bodies so the intellect
knows only spiritual things; for it follows that God and the angels
would not know corporeal things. The reason of this diversity is that
the lower power does not extend to those things that belong to the
higher power; whereas the higher power operates in a more excellent
manner those things which belong to the lower power.

Reply to Objection 3: Every movement presupposes something immovable:
for when a change of quality occurs, the substance remains unmoved; and
when there is a change of substantial form, matter remains unmoved.
Moreover the various conditions of mutable things are themselves
immovable; for instance, though Socrates be not always sitting, yet it
is an immovable truth that whenever he does sit he remains in one
place. For this reason there is nothing to hinder our having an
immovable science of movable things.
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Whether the soul understands corporeal things through its essence?

Objection 1: It would seem that the soul understands corporeal things
through its essence. For Augustine says (De Trin. x, 5) that the soul
"collects and lays hold of the images of bodies which are formed in the
soul and of the soul: for in forming them it gives them something of
its own substance. " But the soul understands bodies by images of
bodies. Therefore the soul knows bodies through its essence, which it
employs for the formation of such images, and from which it forms them.

Objection 2: Further, the Philosopher says (De Anima iii, 8) that "the
soul, after a fashion, is everything. " Since, therefore, like is known
by like, it seems that the soul knows corporeal things through itself.

Objection 3: Further, the soul is superior to corporeal creatures. Now
lower things are in higher things in a more eminent way than in
themselves, as Dionysius says (Coel. Hier. xii). Therefore all
corporeal creatures exist in a more excellent way in the soul than in
themselves. Therefore the soul can know corporeal creatures through its
essence.

On the contrary, Augustine says (De Trin. ix, 3) that "the mind gathers
knowledge of corporeal things through the bodily senses. " But the soul
itself cannot be known through the bodily senses. Therefore it does not
know corporeal things through itself.

I answer that, The ancient philosophers held that the soul knows bodies
through its essence. For it was universally admitted that "like is
known by like. " But they thought that the form of the thing known is in
the knower in the same mode as in the thing known. The Platonists
however were of a contrary opinion. For Plato, having observed that the
intellectual soul has an immaterial nature, and an immaterial mode of
knowledge, held that the forms of things known subsist immaterially.
While the earlier natural philosophers, observing that things known are
corporeal and material, held that things known must exist materially
even in the soul that knows them. And therefore, in order to ascribe to
the soul a knowledge of all things, they held that it has the same
nature in common with all. And because the nature of a result is
determined by its principles, they ascribed to the soul the nature of a
principle; so that those who thought fire to be the principle of all,
held that the soul had the nature of fire; and in like manner as to air
and water. Lastly, Empedocles, who held the existence of our four
material elements and two principles of movement, said that the soul
was composed of these. Consequently, since they held that things exist
in the soul materially, they maintained that all the soul's knowledge
is material, thus failing to discern intellect from sense.

But this opinion will not hold. First, because in the material
principle of which they spoke, the various results do not exist save in
potentiality. But a thing is not known according as it is in
potentiality, but only according as it is in act, as is shown Metaph.
ix (Did. viii, 9): wherefore neither is a power known except through
its act. It is therefore insufficient to ascribe to the soul the nature
of the principles in order to explain the fact that it knows all,
unless we further admit in the soul natures and forms of each
individual result, for instance, of bone, flesh, and the like; thus
does Aristotle argue against Empedocles (De Anima i, 5). Secondly,
because if it were necessary for the thing known to exist materially in
the knower, there would be no reason why things which have a material
existence outside the soul should be devoid of knowledge; why, for
instance, if by fire the soul knows fire, that fire also which is
outside the soul should not have knowledge of fire.

We must conclude, therefore, that material things known must needs
exist in the knower, not materially, but immaterially. The reason of
this is, because the act of knowledge extends to things outside the
knower: for we know things even that are external to us. Now by matter
the form of a thing is determined to some one thing. Wherefore it is
clear that knowledge is in inverse ratio of materiality. And
consequently things that are not receptive of forms save materially,
have no power of knowledge whatever---such as plants, as the
Philosopher says (De Anima ii, 12). But the more immaterially a thing
receives the form of the thing known, the more perfect is its
knowledge. Therefore the intellect which abstracts the species not only
from matter, but also from the individuating conditions of matter, has
more perfect knowledge than the senses, which receive the form of the
thing known, without matter indeed, but subject to material conditions.
Moreover, among the senses, sight has the most perfect knowledge,
because it is the least material, as we have remarked above
([672]Q[78], A[3]): while among intellects the more perfect is the more
immaterial.

It is therefore clear from the foregoing, that if there be an intellect
which knows all things by its essence, then its essence must needs have
all things in itself immaterially; thus the early philosophers held
that the essence of the soul, that it may know all things, must be
actually composed of the principles of all material things. Now this is
proper to God, that His Essence comprise all things immaterially as
effects pre-exist virtually in their cause. God alone, therefore,
understands all things through His Essence: but neither the human soul
nor the angels can do so.

Reply to Objection 1: Augustine in that passage is speaking of an
imaginary vision, which takes place through the image of bodies. To the
formation of such images the soul gives part of its substance, just as
a subject is given in order to be informed by some form. In this way
the soul makes such images from itself; not that the soul or some part
of the soul be turned into this or that image; but just as we say that
a body is made into something colored because of its being informed
with color. That this is the sense, is clear from what follows. For he
says that the soul "keeps something"---namely, not informed with such
image---"which is able freely to judge of the species of these images":
and that this is the "mind" or "intellect. " And he says that the part
which is informed with these images---namely, the imagination---is
"common to us and beasts. "

Reply to Objection 2: Aristotle did not hold that the soul is actually
composed of all things, as did the earlier philosophers; he said that
the soul is all things, "after a fashion," forasmuch as it is in
potentiality to all---through the senses, to all things
sensible---through the intellect, to all things intelligible.

Reply to Objection 3: Every creature has a finite and determinate
essence. Wherefore although the essence of the higher creature has a
certain likeness to the lower creature, forasmuch as they have
something in common generically, yet it has not a complete likeness
thereof, because it is determined to a certain species other than the
species of the lower creature. But the Divine Essence is a perfect
likeness of all, whatsoever may be found to exist in things created,
being the universal principle of all.
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Whether the soul understands all things through innate species?

Objection 1: It would seem that the soul understands all things through
innate species. For Gregory says, in a homily for the Ascension (xxix
in Ev. ), that "man has understanding in common with the angels. " But
angels understand all things through innate species: wherefore in the
book De Causis it is said that "every intelligence is full of forms. "
Therefore the soul also has innate species of things, by means of which
it understands corporeal things.

Objection 2: Further, the intellectual soul is more excellent than
corporeal primary matter. But primary matter was created by God under
the forms to which it has potentiality. Therefore much more is the
intellectual soul created by God under intelligible species. And so the
soul understands corporeal things through innate species.

Objection 3: Further, no one can answer the truth except concerning
what he knows. But even a person untaught and devoid of acquired
knowledge, answers the truth to every question if put to him in orderly
fashion, as we find related in the Meno (xv seqq. ) of Plato, concerning
a certain individual. Therefore we have some knowledge of things even
before we acquire knowledge; which would not be the case unless we had
innate species. Therefore the soul understands corporeal things through
innate species.

On the contrary, The Philosopher, speaking of the intellect, says (De
Anima iii, 4) that it is like "a tablet on which nothing is written. "

I answer that, Since form is the principle of action, a thing must be
related to the form which is the principle of an action, as it is to
that action: for instance, if upward motion is from lightness, then
that which only potentially moves upwards must needs be only
potentially light, but that which actually moves upwards must needs be
actually light. Now we observe that man sometimes is only a potential
knower, both as to sense and as to intellect. And he is reduced from
such potentiality to act---through the action of sensible objects on
his senses, to the act of sensation---by instruction or discovery, to
the act of understanding. Wherefore we must say that the cognitive soul
is in potentiality both to the images which are the principles of
sensing, and to those which are the principles of understanding. For
this reason Aristotle (De Anima iii, 4) held that the intellect by
which the soul understands has no innate species, but is at first in
potentiality to all such species.

But since that which has a form actually, is sometimes unable to act
according to that form on account of some hindrance, as a light thing
may be hindered from moving upwards; for this reason did Plato hold
that naturally man's intellect is filled with all intelligible species,
but that, by being united to the body, it is hindered from the
realization of its act. But this seems to be unreasonable. First,
because, if the soul has a natural knowledge of all things, it seems
impossible for the soul so far to forget the existence of such
knowledge as not to know itself to be possessed thereof: for no man
forgets what he knows naturally; that, for instance, the whole is
larger than the part, and such like. And especially unreasonable does
this seem if we suppose that it is natural to the soul to be united to
the body, as we have established above ([673]Q[76] , A[1]): for it is
unreasonable that the natural operation of a thing be totally hindered
by that which belongs to it naturally. Secondly, the falseness of this
opinion is clearly proved from the fact that if a sense be wanting, the
knowledge of what is apprehended through that sense is wanting also:
for instance, a man who is born blind can have no knowledge of colors.
This would not be the case if the soul had innate images of all
intelligible things. We must therefore conclude that the soul does not
know corporeal things through innate species.

Reply to Objection 1: Man indeed has intelligence in common with the
angels, but not in the same degree of perfection: just as the lower
grades of bodies, which merely exist, according to Gregory (Homily on
Ascension, xxix In Ev. ), have not the same degree of perfection as the
higher bodies. For the matter of the lower bodies is not totally
completed by its form, but is in potentiality to forms which it has
not: whereas the matter of heavenly bodies is totally completed by its
form, so that it is not in potentiality to any other form, as we have
said above ([674]Q[66], A[2]). In the same way the angelic intellect is
perfected by intelligible species, in accordance with its nature;
whereas the human intellect is in potentiality to such species.

Reply to Objection 2: Primary matter has substantial being through its
form, consequently it had need to be created under some form: else it
would not be in act. But when once it exists under one form it is in
potentiality to others. On the other hand, the intellect does not
receive substantial being through the intelligible species; and
therefore there is no comparison.

Reply to Objection 3: If questions be put in an orderly fashion they
proceed from universal self-evident principles to what is particular.
Now by such a process knowledge is produced in the mind of the learner.
Wherefore when he answers the truth to a subsequent question, this is
not because he had knowledge previously, but because he thus learns for
the first time. For it matters not whether the teacher proceed from
universal principles to conclusions by questioning or by asserting; for
in either case the mind of the listener is assured of what follows by
that which preceded.
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Whether the intelligible species are derived by the soul from certain
separate forms?

Objection 1: It would seem that the intelligible species are derived by
the soul from some separate forms. For whatever is such by
participation is caused by what is such essentially; for instance, that
which is on fire is reduced to fire as the cause thereof. But the
intellectual soul forasmuch as it is actually understanding,
participates the thing understood: for, in a way, the intellect in act
is the thing understood in act. Therefore what in itself and in its
essence is understood in act, is the cause that the intellectual soul
actually understands. Now that which in its essence is actually
understood is a form existing without matter. Therefore the
intelligible species, by which the soul understands, are caused by some
separate forms.

Objection 2: Further, the intelligible is to the intellect, as the
sensible is to the sense. But the sensible species which are in the
senses, and by which we sense, are caused by the sensible object which
exists actually outside the soul. Therefore the intelligible species,
by which our intellect understands, are caused by some things actually
intelligible, existing outside the soul. But these can be nothing else
than forms separate from matter. Therefore the intelligible forms of
our intellect are derived from some separate substances.

Objection 3: Further, whatever is in potentiality is reduced to act by
something actual. If, therefore, our intellect, previously in
potentiality, afterwards actually understands, this must needs be
caused by some intellect which is always in act. But this is a separate
intellect. Therefore the intelligible species, by which we actually
understand, are caused by some separate substances.

On the contrary, If this were true we should not need the senses in
order to understand. And this is proved to be false especially from the
fact that if a man be wanting in a sense, he cannot have any knowledge
of the sensibles corresponding to that sense.

I answer that, Some have held that the intelligible species of our
intellect are derived from certain separate forms or substances. And
this in two ways. For Plato, as we have said [675](A[1]), held that the
forms of sensible things subsist by themselves without matter; for
instance, the form of a man which he called "per se" man, and the form
or idea of a horse which is called "per se" horse, and so forth. He
said therefore that these forms are participated both by our soul and
by corporeal matter; by our soul, to the effect of knowledge thereof,
and by corporeal matter to the effect of existence: so that, just as
corporeal matter by participating the idea of a stone, becomes an
individuating stone, so our intellect, by participating the idea of a
stone, is made to understand a stone. Now participation of an idea
takes place by some image of the idea in the participator, just as a
model is participated by a copy. So just as he held that the sensible
forms, which are in corporeal matter, are derived from the ideas as
certain images thereof: so he held that the intelligible species of our
intellect are images of the ideas, derived therefrom. And for this
reason, as we have said above [676](A[1]), he referred sciences and
definitions to those ideas.

But since it is contrary to the nature of sensible things that their
forms should subsist without matter, as Aristotle proves in many ways
(Metaph. vi), Avicenna (De Anima v) setting this opinion aside, held
that the intelligible species of all sensible things, instead of
subsisting in themselves without matter, pre-exist immaterially in the
separate intellects: from the first of which, said he, such species are
derived by a second, and so on to the last separate intellect which he
called the "active intelligence," from which, according to him,
intelligible species flow into our souls, and sensible species into
corporeal matter. And so Avicenna agrees with Plato in this, that the
intelligible species of our intellect are derived from certain separate
forms; but these Plato held to subsist of themselves, while Avicenna
placed them in the "active intelligence. " They differ, too, in this
respect, that Avicenna held that the intelligible species do not remain
in our intellect after it has ceased actually to understand, and that
it needs to turn (to the active intellect) in order to receive them
anew. Consequently he does not hold that the soul has innate knowledge,
as Plato, who held that the participated ideas remain immovably in the
soul.

But in this opinion no sufficient reason can be assigned for the soul
being united to the body. For it cannot be said that the intellectual
soul is united to the body for the sake of the body: for neither is
form for the sake of matter, nor is the mover for the sake of the
moved, but rather the reverse. Especially does the body seem necessary
to the intellectual soul, for the latter's proper operation which is to
understand: since as to its being the soul does not depend on the body.
But if the soul by its very nature had an inborn aptitude for receiving
intelligible species through the influence of only certain separate
principles, and were not to receive them from the senses, it would not
need the body in order to understand: wherefore to no purpose would it
be united to the body.

But if it be said that our soul needs the senses in order to
understand, through being in some way awakened by them to the
consideration of those things, the intelligible species of which it
receives from the separate principles: even this seems an insufficient
explanation. For this awakening does not seem necessary to the soul,
except in as far as it is overcome by sluggishness, as the Platonists
expressed it, and by forgetfulness, through its union with the body:
and thus the senses would be of no use to the intellectual soul except
for the purpose of removing the obstacle which the soul encounters
through its union with the body. Consequently the reason of the union
of the soul with the body still remains to be sought.

And if it be said with Avicenna, that the senses are necessary to the
soul, because by them it is aroused to turn to the "active
intelligence" from which it receives the species: neither is this a
sufficient explanation. Because if it is natural for the soul to
understand through species derived from the "active intelligence," it
follows that at times the soul of an individual wanting in one of the
senses can turn to the active intelligence, either from the inclination
of its very nature, or through being roused by another sense, to the
effect of receiving the intelligible species of which the corresponding
sensible species are wanting. And thus a man born blind could have
knowledge of colors; which is clearly untrue. We must therefore
conclude that the intelligible species, by which our soul understands,
are not derived from separate forms.

Reply to Objection 1: The intelligible species which are participated
by our intellect are reduced, as to their first cause, to a first
principle which is by its essence intelligible---namely, God. But they
proceed from that principle by means of the sensible forms and material
things, from which we gather knowledge, as Dionysius says (Div. Nom.
vii).

Reply to Objection 2: Material things, as to the being which they have
outside the soul, may be actually sensible, but not actually
intelligible. Wherefore there is no comparison between sense and
intellect.

Reply to Objection 3: Our passive intellect is reduced from
potentiality to act by some being in act, that is, by the active
intellect, which is a power of the soul, as we have said ([677]Q[79],
A[4]); and not by a separate intelligence, as proximate cause, although
perchance as remote cause.
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Whether the intellectual soul knows material things in the eternal types?

Objection 1: It would seem that the intellectual soul does not know
material things in the eternal types. For that in which anything is
known must itself be known more and previously. But the intellectual
soul of man, in the present state of life, does not know the eternal
types: for it does not know God in Whom the eternal types exist, but is
"united to God as to the unknown," as Dionysius says (Myst. Theolog.
i). Therefore the soul does not know all in the eternal types.

Objection 2: Further, it is written (Rom. 1:20) that "the invisible
things of God are clearly seen . . . by the things that are made. " But
among the invisible things of God are the eternal types. Therefore the
eternal types are known through creatures and not the converse.

Objection 3: Further, the eternal types are nothing else but ideas, for
Augustine says (QQ. 83, qu. 46) that "ideas are permanent types
existing in the Divine mind. " If therefore we say that the intellectual
soul knows all things in the eternal types, we come back to the opinion
of Plato who said that all knowledge is derived from them.

On the contrary, Augustine says (Confess. xii, 25): "If we both see
that what you say is true, and if we both see that what I say is true,
where do we see this, I pray? Neither do I see it in you, nor do you
see it in me: but we both see it in the unchangeable truth which is
above our minds. " Now the unchangeable truth is contained in the
eternal types. Therefore the intellectual soul knows all true things in
the eternal types.

I answer that, As Augustine says (De Doctr. Christ. ii, 11): "If those
who are called philosophers said by chance anything that was true and
consistent with our faith, we must claim it from them as from unjust
possessors. For some of the doctrines of the heathens are spurious
imitations or superstitious inventions, which we must be careful to
avoid when we renounce the society of the heathens.
" Consequently
whenever Augustine, who was imbued with the doctrines of the
Platonists, found in their teaching anything consistent with faith, he
adopted it: and those thing which he found contrary to faith he
amended. Now Plato held, as we have said above [678](A[4]), that the
forms of things subsist of themselves apart from matter; and these he
called ideas, by participation of which he said that our intellect
knows all things: so that just as corporeal matter by participating the
idea of a stone becomes a stone, so our intellect, by participating the
same idea, has knowledge of a stone. But since it seems contrary to
faith that forms of things themselves, outside the things themselves
and apart from matter, as the Platonists held, asserting that "per se"
life or "per se" wisdom are creative substances, as Dionysius relates
(Div. Nom. xi); therefore Augustine (QQ. 83, qu. 46), for the ideas
defended by Plato, substituted the types of all creatures existing in
the Divine mind, according to which types all things are made in
themselves, and are known to the human soul.

When, therefore, the question is asked: Does the human soul know all
things in the eternal types? we must reply that one thing is said to be
known in another in two ways. First, as in an object itself known; as
one may see in a mirror the images of things reflected therein. In this
way the soul, in the present state of life, cannot see all things in
the eternal types; but the blessed who see God, and all things in Him,
thus know all things in the eternal types. Secondly, on thing is said
to be known in another as in a principle of knowledge: thus we might
say that we see in the sun what we see by the sun. And thus we must
needs say that the human soul knows all things in the eternal types,
since by participation of these types we know all things. For the
intellectual light itself which is in us, is nothing else than a
participated likeness of the uncreated light, in which are contained
the eternal types. Whence it is written (Ps. 4:6,7), "Many say: Who
showeth us good things? " which question the Psalmist answers, "The
light of Thy countenance, O Lord, is signed upon us," as though he were
to say: By the seal of the Divine light in us, all things are made
known to us.

But since besides the intellectual light which is in us, intelligible
species, which are derived from things, are required in order for us to
have knowledge of material things; therefore this same knowledge is not
due merely to a participation of the eternal types, as the Platonists
held, maintaining that the mere participation of ideas sufficed for
knowledge. Wherefore Augustine says (De Trin. iv, 16): "Although the
philosophers prove by convincing arguments that all things occur in
time according to the eternal types, were they able to see in the
eternal types, or to find out from them how many kinds of animals there
are and the origin of each? Did they not seek for this information from
the story of times and places? "

But that Augustine did not understand all things to be known in their
"eternal types" or in the "unchangeable truth," as though the eternal
types themselves were seen, is clear from what he says (QQ. 83, qu.
46)---viz. that "not each and every rational soul can be said to be
worthy of that vision," namely, of the eternal types, "but only those
that are holy and pure," such as the souls of the blessed.

From what has been said the objections are easily solved.
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Whether intellectual knowledge is derived from sensible things?

Objection 1: It would seem that intellectual knowledge is not derived
from sensible things. For Augustine says (QQ. 83, qu. 9) that "we
cannot expect to learn the fulness of truth from the senses of the
body. " This he proves in two ways. First, because "whatever the bodily
senses reach, is continually being changed; and what is never the same
cannot be perceived. " Secondly, because, "whatever we perceive by the
body, even when not present to the senses, may be present to the
imagination, as when we are asleep or angry: yet we cannot discern by
the senses, whether what we perceive be the sensible object or the
deceptive image thereof. Now nothing can be perceived which cannot be
distinguished from its counterfeit. " And so he concludes that we cannot
expect to learn the truth from the senses. But intellectual knowledge
apprehends the truth. Therefore intellectual knowledge cannot be
conveyed by the senses.

Objection 2: Further, Augustine says (Gen. ad lit. xii, 16): "We must
not thing that the body can make any impression on the spirit, as
though the spirit were to supply the place of matter in regard to the
body's action; for that which acts is in every way more excellent than
that which it acts on. " Whence he concludes that "the body does not
cause its image in the spirit, but the spirit causes it in itself. "
Therefore intellectual knowledge is not derived from sensible things.

Objection 3: Further, an effect does not surpass the power of its
cause. But intellectual knowledge extends beyond sensible things: for
we understand some things which cannot be perceived by the senses.
Therefore intellectual knowledge is not derived from sensible things.

On the contrary, The Philosopher says (Metaph. i, 1; Poster. ii, 15)
that the principle of knowledge is in the senses.

I answer that, On this point the philosophers held three opinions. For
Democritus held that "all knowledge is caused by images issuing from
the bodies we think of and entering into our souls," as Augustine says
in his letter to Dioscorus (cxviii, 4). And Aristotle says (De Somn. et
Vigil. ) that Democritus held that knowledge is cause by a "discharge of
images. " And the reason for this opinion was that both Democritus and
the other early philosophers did not distinguish between intellect and
sense, as Aristotle relates (De Anima iii, 3). Consequently, since the
sense is affected by the sensible, they thought that all our knowledge
is affected by this mere impression brought about by sensible things.
Which impression Democritus held to be caused by a discharge of images.

Plato, on the other hand, held that the intellect is distinct from the
senses: and that it is an immaterial power not making use of a
corporeal organ for its action. And since the incorporeal cannot be
affected by the corporeal, he held that intellectual knowledge is not
brought about by sensible things affecting the intellect, but by
separate intelligible forms being participated by the intellect, as we
have said above ([679]AA[4] ,5). Moreover he held that sense is a power
operating of itself. Consequently neither is sense, since it is a
spiritual power, affected by the sensible: but the sensible organs are
affected by the sensible, the result being that the soul is in a way
roused to form within itself the species of the sensible. Augustine
seems to touch on this opinion (Gen. ad lit. xii, 24) where he says
that the "body feels not, but the soul through the body, which it makes
use of as a kind of messenger, for reproducing within itself what is
announced from without. " Thus according to Plato, neither does
intellectual knowledge proceed from sensible knowledge, nor sensible
knowledge exclusively from sensible things; but these rouse the
sensible soul to the sentient act, while the senses rouse the intellect
to the act of understanding.

Aristotle chose a middle course. For with Plato he agreed that
intellect and sense are different. But he held that the sense has not
its proper operation without the cooperation of the body; so that to
feel is not an act of the soul alone, but of the "composite. " And he
held the same in regard to all the operations of the sensitive part.
Since, therefore, it is not unreasonable that the sensible objects
which are outside the soul should produce some effect in the
"composite," Aristotle agreed with Democritus in this, that the
operations of the sensitive part are caused by the impression of the
sensible on the sense: not by a discharge, as Democritus said, but by
some kind of operation. For Democritus maintained that every operation
is by way of a discharge of atoms, as we gather from De Gener. i, 8.
But Aristotle held that the intellect has an operation which is
independent of the body's cooperation. Now nothing corporeal can make
an impression on the incorporeal. And therefore in order to cause the
intellectual operation according to Aristotle, the impression caused by
the sensible does not suffice, but something more noble is required,
for "the agent is more noble than the patient," as he says (De Gener.
i, 5). Not, indeed, in the sense that the intellectual operation is
effected in us by the mere intellectual operation is effected in us by
the mere impression of some superior beings, as Plato held; but that
the higher and more noble agent which he calls the active intellect, of
which we have spoken above ([680]Q[79], AA[3],4) causes the phantasms
received from the senses to be actually intelligible, by a process of
abstraction.

According to this opinion, then, on the part of the phantasms,
intellectual knowledge is caused by the senses. But since the phantasms
cannot of themselves affect the passive intellect, and require to be
made actually intelligible by the active intellect, it cannot be said
that sensible knowledge is the total and perfect cause of intellectual
knowledge, but rather that it is in a way the material cause.

Reply to Objection 1: Those words of Augustine mean that we must not
expect the entire truth from the senses. For the light of the active
intellect is needed, through which we achieve the unchangeable truth of
changeable things, and discern things themselves from their likeness.

Reply to Objection 2: In this passage Augustine speaks not of
intellectual but of imaginary knowledge. And since, according to the
opinion of Plato, the imagination has an operation which belongs to the
soul only, Augustine, in order to show that corporeal images are
impressed on the imagination, not by bodies but by the soul, uses the
same argument as Aristotle does in proving that the active intellect
must be separate, namely, because "the agent is more noble than the
patient. " And without doubt, according to the above opinion, in the
imagination there must needs be not only a passive but also an active
power. But if we hold, according to the opinion of Aristotle, that the
action of the imagination, is an action of the "composite," there is no
difficulty; because the sensible body is more noble than the organ of
the animal, in so far as it is compared to it as a being in act to a
being in potentiality; even as the object actually colored is compared
to the pupil which is potentially colored. It may, however, be said,
although the first impression of the imagination is through the agency
of the sensible, since "fancy is movement produced in accordance with
sensation" (De Anima iii, 3), that nevertheless there is in man an
operation which by synthesis and analysis forms images of various
things, even of things not perceived by the senses. And Augustine's
words may be taken in this sense.

Reply to Objection 3: Sensitive knowledge is not the entire cause of
intellectual knowledge. And therefore it is not strange that
intellectual knowledge should extend further than sensitive knowledge.
__________________________________________________________________

Whether the intellect can actually understand through the intelligible
species of which it is possessed, without turning to the phantasms?

Objection 1: It would seem that the intellect can actually understand
through the intelligible species of which it is possessed, without
turning to the phantasms. For the intellect is made actual by the
intelligible species by which it is informed. But if the intellect is
in act, it understands. Therefore the intelligible species suffices for
the intellect to understand actually, without turning to the phantasms.

Objection 2: Further, the imagination is more dependent on the senses
than the intellect on the imagination. But the imagination can actually
imagine in the absence of the sensible. Therefore much more can the
intellect understand without turning to the phantasms.

Objection 3: There are no phantasms of incorporeal things: for the
imagination does not transcend time and space. If, therefore, our
intellect cannot understand anything actually without turning to the
phantasms, it follows that it cannot understand anything incorporeal.
Which is clearly false: for we understand truth, and God, and the
angels.

On the contrary, The Philosopher says (De Anima iii, 7) that "the soul
understands nothing without a phantasm. "

I answer that, In the present state of life in which the soul is united
to a passible body, it is impossible for our intellect to understand
anything actually, except by turning to the phantasms. First of all
because the intellect, being a power that does not make use of a
corporeal organ, would in no way be hindered in its act through the
lesion of a corporeal organ, if for its act there were not required the
act of some power that does make use of a corporeal organ. Now sense,
imagination and the other powers belonging to the sensitive part, make
use of a corporeal organ. Wherefore it is clear that for the intellect
to understand actually, not only when it acquires fresh knowledge, but
also when it applies knowledge already acquired, there is need for the
act of the imagination and of the other powers. For when the act of the
imagination is hindered by a lesion of the corporeal organ, for
instance in a case of frenzy; or when the act of the memory is
hindered, as in the case of lethargy, we see that a man is hindered
from actually understanding things of which he had a previous
knowledge. Secondly, anyone can experience this of himself, that when
he tries to understand something, he forms certain phantasms to serve
him by way of examples, in which as it were he examines what he is
desirous of understanding. For this reason it is that when we wish to
help someone to understand something, we lay examples before him, from
which he forms phantasms for the purpose of understanding.

Now the reason of this is that the power of knowledge is proportioned
to the thing known. Wherefore the proper object of the angelic
intellect, which is entirely separate from a body, is an intelligible
substance separate from a body. Whereas the proper object of the human
intellect, which is united to a body, is a quiddity or nature existing
in corporeal matter; and through such natures of visible things it
rises to a certain knowledge of things invisible. Now it belongs to
such a nature to exist in an individual, and this cannot be apart from
corporeal matter: for instance, it belongs to the nature of a stone to
be in an individual stone, and to the nature of a horse to be in an
individual horse, and so forth. Wherefore the nature of a stone or any
material thing cannot be known completely and truly, except in as much
as it is known as existing in the individual. Now we apprehend the
individual through the senses and the imagination. And, therefore, for
the intellect to understand actually its proper object, it must of
necessity turn to the phantasms in order to perceive the universal
nature existing in the individual. But if the proper object of our
intellect were a separate form; or if, as the Platonists say, the
natures of sensible things subsisted apart from the individual; there
would be no need for the intellect to turn to the phantasms whenever it
understands.

Reply to Objection 1: The species preserved in the passive intellect
exist there habitually when it does not understand them actually, as we
have said above ([681]Q[79], A[6]). Wherefore for us to understand
actually, the fact that the species are preserved does not suffice; we
need further to make use of them in a manner befitting the things of
which they are the species, which things are natures existing in
individuals.

Reply to Objection 2: Even the phantasm is the likeness of an
individual thing; wherefore the imagination does not need any further
likeness of the individual, whereas the intellect does.

Reply to Objection 3: Incorporeal things, of which there are no
phantasms, are known to us by comparison with sensible bodies of which
there are phantasms. Thus we understand truth by considering a thing of
which we possess the truth; and God, as Dionysius says (Div. Nom. i),
we know as cause, by way of excess and by way of remotion. Other
incorporeal substances we know, in the present state of life, only by
way of remotion or by some comparison to corporeal things. And,
therefore, when we understand something about these things, we need to
turn to phantasms of bodies, although there are no phantasms of the
things themselves.
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Whether the judgment of the intellect is hindered through suspension of the
sensitive powers?

Objection 1: It would seem that the judgment of the intellect is not
hindered by suspension of the sensitive powers. For the superior does
not depend on the inferior. But the judgment of the intellect is higher
than the senses. Therefore the judgment of the intellect is not
hindered through suspension of the senses.

Objection 2: Further, to syllogize is an act of the intellect. But
during sleep the senses are suspended, as is said in De Somn. et Vigil.
i and yet it sometimes happens to us to syllogize while asleep.
Therefore the judgment of the intellect is not hindered through
suspension of the senses.

On the contrary, What a man does while asleep, against the moral law,
is not imputed to him as a sin; as Augustine says (Gen. ad lit. xii,
15). But this would not be the case if man, while asleep, had free use
of his reason and intellect. Therefore the judgment of the intellect is
hindered by suspension of the senses.

I answer that, As we have said above [682](A[7]), our intellect's
proper and proportionate object is the nature of a sensible thing. Now
a perfect judgment concerning anything cannot be formed, unless all
that pertains to that thing's nature be known; especially if that be
ignored which is the term and end of judgment. Now the Philosopher says
(De Coel. iii), that "as the end of a practical science is action, so
the end of natural science is that which is perceived principally
through the senses"; for the smith does not seek knowledge of a knife
except for the purpose of action, in order that he may produce a
certain individual knife; and in like manner the natural philosopher
does not seek to know the nature of a stone and of a horse, save for
the purpose of knowing the essential properties of those things which
he perceives with his senses. Now it is clear that a smith cannot judge
perfectly of a knife unless he knows the action of the knife: and in
like manner the natural philosopher cannot judge perfectly of natural
things, unless he knows sensible things. But in the present state of
life whatever we understand, we know by comparison to natural sensible
things. Consequently it is not possible for our intellect to form a
perfect judgment, while the senses are suspended, through which
sensible things are known to us.

Reply to Objection 1: Although the intellect is superior to the senses,
nevertheless in a manner it receives from the senses, and its first and
principal objects are founded in sensible things. And therefore
suspension of the senses necessarily involves a hindrance to the
judgment of the intellect.

Reply to Objection 2: The senses are suspended in the sleeper through
certain evaporations and the escape of certain exhalations, as we read
in De Somn. et Vigil. iii. And, therefore, according to the amount of
such evaporation, the senses are more or less suspended. For when the
amount is considerable, not only are the senses suspended, but also the
imagination, so that there are no phantasms; thus does it happen,
especially when a man falls asleep after eating and drinking copiously.
If, however, the evaporation be somewhat less, phantasms appear, but
distorted and without sequence; thus it happens in a case of fever. And
if the evaporation be still more attenuated, the phantasms will have a
certain sequence: thus especially does it happen towards the end of
sleep in sober men and those who are gifted with a strong imagination.
If the evaporation be very slight, not only does the imagination retain
its freedom, but also the common sense is partly freed; so that
sometimes while asleep a man may judge that what he sees is a dream,
discerning, as it were, between things, and their images. Nevertheless,
the common sense remains partly suspended; and therefore, although it
discriminates some images from the reality, yet is it always deceived
in some particular. Therefore, while man is asleep, according as sense
and imagination are free, so is the judgment of his intellect
unfettered, though not entirely. Consequently, if a man syllogizes
while asleep, when he wakes up he invariably recognizes a flaw in some
respect.
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OF THE MODE AND ORDER OF UNDERSTANDING (EIGHT ARTICLES)

We come now to consider the mode and order of understanding. Under this
head there are eight points of inquiry:

(1) Whether our intellect understands by abstracting the species from
the phantasms?

(2) Whether the intelligible species abstracted from the phantasms are
what our intellect understands, or that whereby it understands?

(3) Whether our intellect naturally first understands the more
universal?

(4) Whether our intellect can know many things at the same time?

(5) Whether our intellect understands by the process of composition and
division?

(6) Whether the intellect can err?

(7) Whether one intellect can understand better than another?

(8) Whether our intellect understands the indivisible before the
divisible?
__________________________________________________________________

Whether our intellect understands corporeal and material things by
abstraction from phantasms?

Objection 1: It would seem that our intellect does not understand
corporeal and material things by abstraction from the phantasms. For
the intellect is false if it understands an object otherwise than as it
really is. Now the forms of material things do not exist as abstracted
from the particular things represented by the phantasms. Therefore, if
we understand material things by abstraction of the species from the
phantasm, there will be error in the intellect.

Objection 2: Further, material things are those natural things which
include matter in their definition. But nothing can be understood apart
from that which enters into its definition. Therefore material things
cannot be understood apart from matter. Now matter is the principle of
individualization. Therefore material things cannot be understood by
abstraction of the universal from the particular, which is the process
whereby the intelligible species is abstracted from the phantasm.

Objection 3: Further, the Philosopher says (De Anima iii, 7) that the
phantasm is to the intellectual soul what color is to the sight. But
seeing is not caused by abstraction of species from color, but by color
impressing itself on the sight. Therefore neither does the act of
understanding take place by abstraction of something from the phantasm,
but by the phantasm impressing itself on the intellect.

Objection 4: Further, the Philosopher says (De Anima iii, 5) there are
two things in the intellectual soul---the passive intellect and the
active intellect. But it does not belong to the passive intellect to
abstract the intelligible species from the phantasm, but to receive
them when abstracted. Neither does it seem to be the function of the
active intellect, which is related to the phantasm, as light is to
color; since light does not abstract anything from color, but rather
streams on to it. Therefore in no way do we understand by abstraction
from phantasms.

Objection 5: Further, the Philosopher (De Anima iii, 7) says that "the
intellect understands the species in the phantasm"; and not, therefore,
by abstraction.

On the contrary, The Philosopher says (De Anima iii, 4) that "things
are intelligible in proportion as they are separate from matter. "
Therefore material things must needs be understood according as they
are abstracted from matter and from material images, namely, phantasms.

I answer that, As stated above ([683]Q[84], A[7]), the object of
knowledge is proportionate to the power of knowledge. Now there are
three grades of the cognitive powers. For one cognitive power, namely,
the sense, is the act of a corporeal organ. And therefore the object of
every sensitive power is a form as existing in corporeal matter. And
since such matter is the principle of individuality, therefore every
power of the sensitive part can only have knowledge of the individual.
There is another grade of cognitive power which is neither the act of a
corporeal organ, nor in any way connected with corporeal matter; such
is the angelic intellect, the object of whose cognitive power is
therefore a form existing apart from matter: for though angels know
material things, yet they do not know them save in something
immaterial, namely, either in themselves or in God. But the human
intellect holds a middle place: for it is not the act of an organ; yet
it is a power of the soul which is the form the body, as is clear from
what we have said above ([684]Q[76], A[1]). And therefore it is proper
to it to know a form existing individually in corporeal matter, but not
as existing in this individual matter. But to know what is in
individual matter, not as existing in such matter, is to abstract the
form from individual matter which is represented by the phantasms.
Therefore we must needs say that our intellect understands material
things by abstracting from the phantasms; and through material things
thus considered we acquire some knowledge of immaterial things, just
as, on the contrary, angels know material things through the
immaterial.

But Plato, considering only the immateriality of the human intellect,
and not its being in a way united to the body, held that the objects of
the intellect are separate ideas; and that we understand not by
abstraction, but by participating things abstract, as stated above
([685]Q[84] , A[1]).

Reply to Objection 1: Abstraction may occur in two ways: First, by way
of composition and division; thus we may understand that one thing does
not exist in some other, or that it is separate therefrom.