y reason of its very
existence; but is compared to these intelligible things as a
potentiality to act.

Now, potentiality has a double relation to act. There is a
potentiality which is always perfected by its act: as the matter of
the heavenly bodies (Q. 58, A. 1). And there is another potentiality
which is not always in act, but proceeds from potentiality to act; as
we observe in things that are corrupted and generated. Wherefore the
angelic intellect is always in act as regards those things which it
can understand, by reason of its proximity to the first intellect,
which is pure act, as we have said above. But the human intellect,
which is the lowest in the order of intelligence and most remote
from the perfection of the Divine intellect, is in potentiality with
regard to things intelligible, and is at first "like a clean tablet
on which nothing is written," as the Philosopher says (De Anima iii,
4). This is made clear from the fact, that at first we are only in
potentiality to understand, and afterwards we are made to understand
actually. And so it is evident that with us to understand is "in a
way to be passive"; taking passion in the third sense. And
consequently the intellect is a passive power.

Reply Obj. 1: This objection is verified of passion in the first and
second senses, which belong to primary matter. But in the third sense
passion is in anything which is reduced from potentiality to act.

Reply Obj. 2: "Passive intellect" is the name given by some to the
sensitive appetite, in which are the passions of the soul; which
appetite is also called "rational by participation," because it
"obeys the reason" (Ethic. i, 13). Others give the name of passive
intellect to the cogitative power, which is called the "particular
reason." And in each case "passive" may be taken in the two first
senses; forasmuch as this so-called intellect is the act of a
corporeal organ. But the intellect which is in potentiality to things
intelligible, and which for this reason Aristotle calls the
"possible" intellect (De Anima iii, 4) is not passive except in the
third sense: for it is not an act of a corporeal organ. Hence it is
incorruptible.

Reply Obj. 3: The agent is nobler than the patient, if the action and
the passion are referred to the same thing: but not always, if they
refer to different things. Now the intellect is a passive power in
regard to the whole universal being: while the vegetative power is
active in regard