summa-contra-gentiles

2IO
THE SUMMA CONTRA GENTILES
remote agent. Therefore it follows that in us there must be
a proximate principle
of such an effect : and this is the
active intellect. Therefore it is not a separate substance,
but a power of our soul.
Again. The nature of every mover includes a principle
sufficient for the natural operation thereof : and if this
operation consists in an action, that nature includes an
active principle, as appears in the powers of the nutritive
soul of plants ;
while if this operation is a passion,
it includes
a passive principle, as appears in the sensitive powers of
animals. Now man is the most perfect of all lower movers.
And his proper and natural operation
is to understand ;
which is not completed without some passion, in so far as
the intellect is passive to the intelligible ;
nor again without
action, in so far as the intellect makes things that are
potentially intelligible to be intelligible actually. Therefore
the respective principles of both, namely the active and
possible intellects, must be in man's nature and neither of
these must be separate, as to its being, from the soul of
man.
Again.
If the active intellect be a separate substance, it
is evident that it is above man's nature. Now an operation
which man performs by the power alone of a higher substance
is a supernatural operation such as the ; working of
miracles, prophesying, and other like things which men do
by God's favour. Since, then, man cannot understand
except by the power of the active intellect, if the active
intellect be a separate substance,
it will follow that in-
to man : and conse-
telligence is not a natural operation
quently man cannot be defined as being intellectual and
rational.
Further. Nothing operates save by a power that is in it
formally wherefore Aristotle : (2 De AnimaY proves that
the thing whereby we live and sense is a form and an
act. Now both actions, namely of the active and possible
intellects, are competent to man : for man abstracts from
phantasms, and receives in his mind actual intelligibles ;