What Good and Evil Are by Baruch Spinoza

Some things are in our understanding and not in Nature, and so they are also only our own creation, and their purpose is to understand things distinctly: among these we include all relations, which have reference to different things, and these we call Entia Rationis [things of thought]. Now the question is, whether good and evil belong to the Entia Rationis or to the Entia Realia [real things]. But since good and evil are only relations, it is beyond doubt that they must be placed among the Entia Rationis; for we never say that something is good except with reference to something else which is not so good, or is not so useful to us as some other thing. Thus we say that a man is bad, only in comparison with one who is better, or also that an apple is bad, in comparison with another which is good or better.

All this could not possibly be said, if that which is better or good, in comparison with which it [the bad] is so called, did not exist.