Raymond E. Feist said this quote

Have you ever wronged a man . . . just to do him harm? Or have you always had a reason?’Kaspar answered quickly. ‘There was always a reason.’‘There you have it,’ said Samas as he sat down. He motioned for Kaspar to fetch over a cup of water for him. ‘You would never look at yourself as “evil” no matter what the other fellow thought of what you did. It’s in our nature. And that’s the great secret of evil. It is never viewed as evil by those who perpetrate the evil.