, Did. viii, 8. Therefore the first thing understood of
the intellect is its own act of understanding. This occurs in
different ways with different intellects. For there is an intellect,
namely, the Divine, which is Its own act of intelligence, so that in
God the understanding of His intelligence, and the understanding of
His Essence, are one and the same act, because His Essence is His act
of understanding. But there is another intellect, the angelic, which
is not its own act of understanding, as we have said above (Q. 79,
A. 1), and yet the first object of that act is the angelic essence.
Wherefore although there is a logical distinction between the act
whereby he understands that he understands, and that whereby he
understands his essence, yet he understands both by one and the same
act; because to understand his own essence is the proper perfection
of his essence, and by one and the same act is a thing, together with
its perfection, understood. And there is yet another, namely, the
human intellect, which neither is its own act of understanding, nor
is its own essence the first object of its act of understanding, for
this object is the nature of a material thing. And therefore that
which is first known by the human intellect is an object of this
kind, and that which is known secondarily is the act by which that
object is known; and through the act the intellect itself is known,
the perfection of which is this act of understanding. For this reason
did the Philosopher assert that objects are known before acts, and
acts before powers (De Anima ii, 4).

Reply Obj. 1: The object of the intellect is something universal,
namely, _being_ and _the true,_ in which the act also of
understanding is comprised. Wherefore the intellect can understand
its own act. But not primarily, since the first object of our
intellect, in this state of life, is not every being and everything
true, but _being_ and _true,_ as considered in material things, as
we have said above (Q. 84, A. 7), from which it acquires knowledge
of all other things.

Reply Obj. 2: The intelligent act of the human intellect is not the
act and perfection of the material nature understood, as if the
nature of the material thing and intelligent act could be understood
by one act; just as a thing and its perfection are understood by one
act. Hence the act whereby the intellect understands a stone is
distinct from the act whereby it understands that it understands a
ston