summa-contra-gentiles

CHAPTER LXX'VIII 215
light connatural to us. Therefore nothing hinders us from
ascribing the action of the active intellect to the light of our
soul, and especially since Aristotle compares the active
^
intellect to a light.
CHAPTER LXXVni
THAT Aristotle's opinion concerning the active intellect
WAS NOT THAT IT IS A SEPARATE SUBSTANCE, BUT RATHER
THAT IT IS PART OF THE SOUL
Since however some agree with the above opinion' in the
belief that it reflects the mind of Aristotle, we must show
from his words that in his opinion the active intellect is not
a separate substance.
For he says,' in the first place, that just as in every
nature there is
something like the matter in every genus,
which is in potentiality to all that comes under that genus ;
while there is also a cause like the efficient cause, as art
in relation to matter, so must these differences he in the
soul. The latter, namely that which is as matter in the soul,
is the (possible) intellect wherein all things intelligible are
made : whereas the former, which is as the efficient cause in
the soul, is the intellect by which we make all things (namely
actually intelligible), and this is the active intellect, which
is like a habit, and not a power. In what sense he calls the
active intellect a habit, he explains by adding that it is as a
light, since in a manner light makes potential colours to be
colours actually, in so far, to wit, as it makes them to be
actually visible : because this is what is ascribed to the
active intellect in regard to intelligibles.
From this we gather that the active intellect is not a
separate substance but rather a part of the soul : for he
says explicitly that the possible and active intellect are
differences of the soul and that they are in the soul. Therefore
neither of them is a separate substance.
Again. His argument proves this also. Because in
^ 3 De Anitna, he. cii. « Ch. Ixxvi. 3 De Anima v. i.