is not a passive
power.

Obj. 2: Further, the intellectual power is incorruptible, as we have
said above (Q. 79, A. 6). But "if the intellect is passive, it is
corruptible" (De Anima iii, 5). Therefore the intellectual power is
not passive.

Obj. 3: Further, the "agent is nobler than the patient," as Augustine
(Gen. ad lit. xii, 16) and Aristotle (De Anima iii, 5) says. But all
the powers of the vegetative part are active; yet they are the lowest
among the powers of the soul. Much more, therefore, all the
intellectual powers, which are the highest, are active.

_On the contrary,_ The Philosopher says (De Anima iii, 4) that "to
understand is in a way to be passive."

_I answer that,_ To be passive may be taken in three ways. Firstly,
in its most strict sense, when from a thing is taken something which
belongs to it by virtue either of its nature, or of its proper
inclination: as when water loses coolness by heating, and as when a
man becomes ill or sad. Secondly, less strictly, a thing is said to
be passive, when something, whether suitable or unsuitable, is taken
away from it. And in this way not only he who is ill is said to be
passive, but also he who is healed; not only he that is sad, but also
he that is joyful; or whatever way he be altered or moved. Thirdly,
in a wide sense a thing is said to be passive, from the very fact
that what is in potentiality to something receives that to which it
was in potentiality, without being deprived of anything. And
accordingly, whatever passes from potentiality to act, may be said to
be passive, even when it is perfected. And thus with us to understand
is to be passive. This is clear from the following reason. For the
intellect, as we have seen above (Q. 78, A. 1), has an operation
extending to universal being. We may therefore see whether the
intellect be in act or potentiality by observing first of all the
nature of the relation of the intellect to universal being. For we
find an intellect whose relation to universal being is that of the
act of all being: and such is the Divine intellect, which is the
Essence of God, in which originally and virtually, all being
pre-exists as in its first cause. And therefore the Divine intellect
is not in potentiality, but is pure act. But no created intellect can
be an act in relation to the whole universal being; otherwise it
would needs be an infinite being. Wherefore every created intellect
is not the act of all things intelligible, b