to be found in existence itself; for some things there are
which cannot lose their existence as incorruptible things, while
some there are which can lose it, as things corruptible.

As, therefore, the perfection of the universe requires that there
should be not only beings incorruptible, but also corruptible beings;
so the perfection of the universe requires that there should be some
which can fail in goodness, and thence it follows that sometimes they
do fail. Now it is in this that evil consists, namely, in the fact
that a thing fails in goodness. Hence it is clear that evil is found
in things, as corruption also is found; for corruption is itself an
evil.

Reply Obj. 1: Evil is distant both from simple being and from simple
"not-being," because it is neither a habit nor a pure negation, but a
privation.

Reply Obj. 2: As the Philosopher says (Metaph. v, text 14), being is
twofold. In one way it is considered as signifying the entity of a
thing, as divisible by the ten "predicaments"; and in that sense it
is convertible with thing, and thus no privation is a being, and
neither therefore is evil a being. In another sense being conveys the
truth of a proposition which unites together subject and attribute by
a copula, notified by this word "is"; and in this sense being is what
answers to the question, "Does it exist?" and thus we speak of
blindness as being in the eye; or of any other privation. In this way
even evil can be called a being. Through ignorance of this
distinction some, considering that things may be evil, or that evil
is said to be in things, believed that evil was a positive thing in
itself.

Reply Obj. 3: God and nature and any other agent make what is best in
the whole, but not what is best in every single part, except in order
to the whole, as was said above (Q. 47, A. 2). And the whole itself,
which is the universe of creatures, is all the better and more
perfect if some things in it can fail in goodness, and do sometimes
fail, God not preventing this. This happens, firstly, because "it
belongs to Providence not to destroy, but to save nature," as
Dionysius says (Div. Nom. iv); but it belongs to nature that what may
fail should sometimes fail; secondly, because, as Augustine says
(Enchir. 11), "God is so powerful that He can even make good out of
evil." Hence many good things would be taken away if God permitted no
evil to exist; for fire would not be generated if air was not
corrupted, nor wou