Whether the Intellectual Soul Knows Itself by Its Essence?
Objection 1: It would seem that the intellectual soul knows itself by
its own essence. For Augustine says (De Trin. ix, 3), that "the mind
knows itself, because it is incorporeal."
Obj. 2: Further, both angels and human souls belong to the genus of
intellectual substance. But an angel understands itself by its own
essence. Therefore likewise does the human soul.
Obj. 3: Further, "in things void of matter, the intellect and that
which is understood are the same" (De Anima iii, 4). But the human
mind is void of matter, not being the act of a body as stated above
(Q. 76, A. 1). Therefore the intellect and its object are the same in
the human mind; and therefore the human mind understands itself by
its own essence.
_On the contrary,_ It is said (De Anima iii, 4) that "the intellect
understands itself in the same way as it understands other things."
But it understands other things, not by their essence, but by their
similitudes. Therefore it does not understand itself by its own
essence.
_I answer that,_ Everything is knowable so far as it is in act, and
not, so far as it is in potentiality (Metaph. ix, Did. viii, 9): for
a thing is a being, and is true, and therefore knowable, according as
it is actual. This is quite clear as regards sensible things, for the
eye does not see what is potentially, but what is actually colored.
In like manner it is clear that the intellect, so far as it knows
material things, does not know save what is in act: and hence it does
not know primary matter except as proportionate to form, as is stated
Phys. i, 7. Consequently immaterial substances are intelligible by
their own essence according as each one is actual by its own essence.
Therefore it is that the Essence of God, the pure and perfect act, is
simply and perfectly in itself intelligible; and hence God by His own
Essence knows Himself, and all other things also. The angelic essence
belongs, indeed, to the genus of intelligible things as _act,_ but
not as a _pure act,_ nor as a _complete act,_ and hence the angel's
act of intelligence is not completed by his essence. For although an
angel understands himself by his own essence, still he cannot
understand all other things by his own essence; for he knows things
other than himself by their likenesses. Now the human intellect is
only a potentiality in the genus of intelligible beings, just as
primary matter is a potentiality as regards sensible beings; and
hence it is called "possible" [*Possibilis--elsewhere in this
translation rendered "passive"--Ed.]. Therefore in its essence the
human mind is potentially understanding. Hence it has in itself the
power to understand, but not to be understood, except as it is made
actual. For even the Platonists asserted that an order of
intelligible beings existed above the order of intellects, forasmuch
as the intellect understands only by participation of the
intelligible; for they said that the participator is below what it
participates. If, therefore, the human intellect, as the Platonists
held, became actual by participating separate intelligible forms, it
would understand itself by such participation of incorporeal beings.
But as in this life our intellect has material and sensible things
for its proper natural object, as stated above (Q. 84, A. 7), it
understands itself according as it is made actual by the species
abstracted from sensible things, through the light of the active
intellect, which not only actuates the intelligible things
themselves, but also, by their instrumentality, actuates the passive
intellect. Therefore the intellect knows itself not by its essence,
but by its act. This happens in two ways: In the first place,
singularly, as when Socrates or Plato perceives that he has an
intellectual soul because he perceives that he understands. In the
second place, universally, as when we consider the nature of the
human mind from knowledge of the intellectual act. It is true,
however, that the judgment and force of this knowledge, whereby we
know the nature of the soul, comes to us according to the derivation
of our intellectual light from the Divine Truth which contains the
types of all things as above stated (Q. 84, A. 5). Hence Augustine
says (De Trin. ix, 6): "We gaze on the inviolable truth whence we can
as perfectly as possible define, not what each man's mind is, but
what it ought to be in the light of the eternal types." There is,
however, a difference between these two kinds of knowledge, and it
consists in this, that the mere presence of the mind suffices for the
first; the mind itself being the principle of action whereby it
perceives itself, and hence it is said to know itself by its own
presence. But as regards the second kind of knowledge, the mere
presence of the mind does not suffice, and there is further required
a careful and subtle inquiry. Hence many are ignorant of the soul's
nature, and many have erred about it. So Augustine says (De Trin. x,
9), concerning such mental inquiry: "Let the mind strive not to see
itself as if it were absent, but to discern itself as present"--i.e.
to know how it differs from other things; which is to know its
essence and nature.
Reply Obj. 1: The mind knows itself by means of itself, because at
length it acquires knowledge of itself, though led thereto by its own
act: because it is itself that it knows, since it loves itself, as he
says in the same passage. For a thing can be called self-evident in
two ways, either because we can know it by nothing else except
itself, as first principles are called self-evident; or because it is
not accidentally knowable, as color is visible of itself, whereas
substance is visible by its accident.
Reply Obj. 2: The essence of an angel is an act in the genus of
intelligible things, and therefore it is both intellect and the thing
understood. Hence an angel apprehends his own essence through itself:
not so the human mind, which is either altogether in potentiality to
intelligible things--as is the passive intellect--or is the act of
intelligible things abstracted from the phantasms--as is the active
intellect.
Reply Obj. 3: This saying of the Philosopher is universally true in
every kind of intellect. For as sense in act is the sensible in act,
by reason of the sensible likeness which is the form of sense in act,
so likewise the intellect in act is the object understood in act, by
reason of the likeness of the thing understood, which is the form of
the intellect in act. So the human intellect, which becomes actual by
the species of the object understood, is itself understood by the
same species as by its own form. Now to say that in "things without
matter the intellect and what is understood are the same," is equal
to saying that "as regards things actually understood the intellect
and what is understood are the same." For a thing is actually
understood in that it is immaterial. But a distinction must be drawn:
since the essences of some things are immaterial--as the separate
substances called angels, each of which is understood and
understands, whereas there are other things whose essences are not
wholly immaterial, but only the abstract likenesses thereof. Hence
the Commentator says (De Anima iii) that the proposition quoted is
true only of separate substances; because in a sense it is verified
in their regard, and not in regard of other substances, as already
stated (Reply Obj. 2).
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