The Republic by Plato Part 1 Page 24

And so, you and Homer and Simonides are agreed that justice is an art of theft; to be practised however ‘for the good of friends and for the harm of enemies,’ — that was what you were saying?

No, certainly not that, though I do not now know what I did say; but I still stand by the latter words.

Well, there is another question: By friends and enemies do we mean those who are so really, or only in seeming?

Surely, he said, a man may be expected to love those whom he thinks good, and to hate those whom he thinks evil.

Yes, but do not persons often err about good and evil: many who are not good seem to be so, and conversely?

That is true.