Certainly there are things worth believing. I believe in the brotherhood of man and in personal originality. But if you asked me to prove what I believe, I couldn't. You can spend your whole life trying to prove what you believe; you may hunt for reasons, but it will all be in vain. Yet our beliefs are like our existence; they are facts. If you don't yet know what to believe in, then try to learn what you feel and desire.

p. 136 - Einstein and the Poet (1983)