Quote Sorin Cerin, Theme Origin : In our existence, absolutely anything that would refer to its...

In our existence, absolutely anything that would refer to its self, as evil to evil and good to good would lead to the annulment of the actual reference, so it is absolutely necessary for a final referent to exist, that is in no way the same as the reference.
For instance, good could never refer to a lesser good if somewhere at the end of the scale were not evil as well, to which we can make the entire array of references to.
So at one of the ends must necessarily be an opposite.