"Some of the most virtuous men are murderers by the fact that they stick to their own principles. Hitler was a virtuous man in the context of his own principles. He initiated a pretty dirty hour as far as humanity was concerned, but the idea is that he did it for his own reasons. They were mad reasons, but he felt that he was sticking to his principles. So even an insane man may have an insane code of ethics."
January 1, 1970
https://en.wikiquote.org/wiki/Virtue