Every serious scientific worker is painfully conscious of this involuntary relegation to an ever-narrowing sphere of knowledge, which threatens to deprive the investigator of his broad horizon and degrades him to the level of a mechanic.

We must remember that we do not observe nature as it actually exists, but nature exposed to our methods of perception. The theories determine what we can or cannot observe...Reality is an illusion, albeit a persistent one.

An expert is a person who has few new ideas; a beginner is a person with many.

This is a question too difficult for a mathematician. It should be asked of a philosopher"(when asked about completing his income tax form)

I believe in intuitions and inspirations...I sometimes FEEL that I am right. I do not KNOW that I am.

The ability to portray people in still life and in motion requires the highest measure of intuition and talent.

The distinctions separating the social classes are false; in the last analysis they rest on force.