Two quotes this time, but I think you'll have to agree that they go together.
“If I wasn’t an actor, I think I’d have gone mad. You have to have extra voltage, some extra temperament to reach certain heights. Art is a little bit larger than life - it’s an exhalation of life and I think I you probably need a little touch of madness” — Sir Laurence Olivier
"Show me a great actor and I'll show you a lousy husband. Show me a great actress, and you've seen the devil." - W. C. Fields