An actor needs something to stabilize his personality, something to nail down what he really is, not what he is currently pretending to be.
Humphrey BogartUgarte: You despise me, don't you? Rick Blaine: If I gave you any thought I probably would.
Humphrey BogartIโm not good-looking. I used to be, but not anymore. Not like Robert Taylor. What I have got is I have character in my face. Itโs taken an awful lot of late nights and drinking to put it there. When I go to work in a picture, I say, โDonโt take the lines out of my face. Leave them there.โ
Humphrey Bogart