which is the subject of evil; for by darkness the substance of the air
is not injured. And there is also a kind of good which is diminished
by evil, but is not wholly taken away; and this good is the aptitude
of a subject to some actuality.

The diminution, however, of this kind of good is not to be considered
by way of subtraction, as diminution in quantity, but rather by way of
remission, as diminution in qualities and forms. The remission
likewise of this habitude is to be taken as contrary to its intensity.
For this kind of aptitude receives its intensity by the dispositions
whereby the matter is prepared for actuality; which the more they are
multiplied in the subject the more is it fitted to receive its
perfection and form; and, on the contrary, it receives its remission
by contrary dispositions which, the more they are multiplied in the
matter, and the more they are intensified, the more is the
potentiality remitted as regards the actuality.

Therefore, if contrary dispositions cannot be multiplied and
intensified to infinity, but only to a certain limit, neither is the
aforesaid aptitude diminished or remitted infinitely, as appears in
the active and passive qualities of the elements; for coldness and
humidity, whereby the aptitude of matter to the form of fire is
diminished or remitted, cannot be infinitely multiplied. But if the
contrary dispositions can be infinitely multiplied, the aforesaid
aptitude is also infinitely diminished or remitted; yet, nevertheless,
it is not wholly taken away, because its root always remains, which is
the substance of the subject. Thus, if opaque bodies were interposed
to infinity between the sun and the air, the aptitude of the air to
light would be infinitely diminished, but still it would never be
wholly removed while the air remained, which in its very nature is
transparent. Likewise, addition in sin can be made to infinitude,
whereby the aptitude of the soul to grace is more and more lessened;
and these sins, indeed, are like obstacles interposed between us and
God, according to Isa. 59:2: "Our sins have divided between us and
God." Yet the aforesaid aptitude of the soul is not wholly taken away,
for it belongs to its very nature.

Reply Obj. 1: The good which is opposed to evil is wholly taken away;
but other goods are not wholly removed, as said above.

Reply Obj. 2: The aforesaid aptitude is a medium between subject and
act. Hence, where it touches act, it is dimin