Men who give up the common goal of all things that exist, thereby cease to exist themselves. Some may perhaps think it strange that we say that wicked men, who form the majority of men, do not exist; but that is how it is. I am not trying to deny the wickedness of the wicked; what I do deny is that their existence is absolute and complete existence. Just as you might call a corpse a dead man, but couldn't simply call it a man ... A thing exists when it keeps its proper place and preserves its own nature. Anything which departs from this ceases to exist, because its existence depends on the preservation of its nature.

boethius, consolation of philosophy, IV.ii, p.91

For you evil does not exist at all, and not only for you but for your created universe, because there is nothing outside it which could break in and destroy the order which you have imposed upon it. But in the parts of the universe, there are certain elements which are thought evil because of a conflict of interest.... All these elements which have some mutual conflict of interest are congruous with the inferior part of the universe which we call earth.... Because my soul did not dare to say that my God displeased me, it refused to attribute to you whatever was displeasing. Hence it came to adopt the opinion that there are two substances.

augustine, confessions, vii.19