But some one says: Why, then, does the true God permit these
things to be done? Why does He not rather remove or destroy the
wicked? Why, in truth, did He from the beginning give power 1486
to the demon, so that there should be one who might corrupt and
destroy all things? I will briefly say why He willed that this
should be so. I ask whether virtue is a good or an evil. It
cannot be denied that it is a good. If virtue is a good, vice,
on the contrary, is an evil. If vice is an evil on this account,
because it opposes virtue, and virtue is on this account a good,
because it overthrows vice, it follows that virtue cannot exist
without vice; and if you take away vice, the merits of virtue
will be taken away. For there can be no victory without an
enemy. Thus it comes to pass, that good cannot exist without an
evil. Chrysippus, a man of active mind, saw this when discussing
the subject of providence, and charges those with folly who
think that good is caused by God, but say that evil is not thus
caused. Aulus Ge