I don't believe I can really do without teaching. The reason is, I have to have something so that when I don't have any ideas and I'm not getting anywhere, I can say to myself, "At least I'm living; at least I'm doing something. I'm making some contribution." It's just psychological.

Surely You're Joking Mr Feynman: Adventures of a Curious Character as Told to Ralph Leighton (ed. Random House, 2014) - ISBN: 9781448181476