 I think it was one of the Greek philosophers, but I've heard a lot of people attributed to this saying, but who said, holding onto resentment is like drinking poison, hoping the other guy dies. You just hurt yourself. You're the one waking up in the middle of the night, irritated and cranky and unable to fall back to sleep because you're ruminating on what the person said or did or didn't do or didn't say. It's like being in prison.