dy said (Q. 44, A. 1). Now the act to which the operative
power is compared is operation. But in the angel to understand is not
the same as to exist, nor is any operation in him, nor in any other
created thing, the same as his existence. Hence the angel's essence is
not his power of intelligence: nor is the essence of any creature its
power of operation.

Reply Obj. 1: An angel is called "intellect" and "mind," because all
his knowledge is intellectual: whereas the knowledge of a soul is
partly intellectual and partly sensitive.

Reply Obj. 2: A simple form which is pure act cannot be the subject
of accident, because subject is compared to accident as potentiality
is to act. God alone is such a form: and of such is Boethius speaking
there. But a simple form which is not its own existence, but is
compared to it as potentiality is to act, can be the subject of
accident; and especially of such accident as follows the species: for
such accident belongs to the form--whereas an accident which belongs
to the individual, and which does not belong to the whole species,
results from the matter, which is the principle of individuation. And
such a simple form is an angel.

Reply Obj. 3: The power of matter is a potentiality in regard to
substantial being itself, whereas the power of operation regards
accidental being. Hence there is no comparison.
_______________________

FOURTH ARTICLE [I, Q. 54, Art. 4]

Whether There Is an Active and a Passive Intellect in an Angel?

Objection 1: It would seem that there is both an active and a passive
intellect in an angel. The Philosopher says (De Anima iii, text. 17)
that, "in the soul, just as in every nature, there is something
whereby it can become all things, and there is something whereby it
can make all things." But an angel is a kind of nature. Therefore
there is an active and a passive intellect in an angel.

Obj. 2: Further, the proper function of the passive intellect is to
receive; whereas to enlighten is the proper function of the active
intellect, as is made clear in _De Anima_ iii, text. 2, 3, 18. But an
angel receives enlightenment from a higher angel, and enlightens a
lower one. Therefore there is in him an active and a passive
intellect.

_On the contrary,_ The distinction of active and passive intellect in
us is in relation to the phantasms, which are compared to the passive
intellect as colors to the sight; but to the active intellect as
colors to the light, as i