I do not play games. There is not time for it. When I get through with work, I don't want anything that requires the working of the mind.

The scientist finds his reward in what Henri Poincare calls the joy of comprehension, and not in the possibility of application to which any discovery may lead.

There is nothing divine about morality, it is a purely human affair.

I assert that the cosmic religious experience is the strongest and the noblest driving force behind scientific research.

We cannot despair of humanity, since we ourselves are human beings.

To stimulate creativity one must develop childlike inclination for play and the childlike desire for recognition.

I am not a positivist. Positivism states that what cannot be observed does not exist. This conception is scientifically indefensible, for it is impossible to make valid affirmations of what people 'can' or 'cannot' observe. One would have to say 'only what we observe exists,' which is obviously false.