I think that we all know what evil is. We have a sense of what's evil, and certainly killing innocent people is evil. We're less sure about what is good. There's sort of good, good enough, could be better - but absolute good is a little harder to define.
“If you want to make an audience laugh, you dress a man up like an old lady and push her down the stairs. If you want to make comedy writers laugh, you push an actual old lady down the stairs.”