[There is] a duty in refusing to cooperate in any undertaking that violates the Constitutional rights of the individual. This holds in particular for all inquisitions that are concerned with the private life and the political affiliations of the citizens.

I live in that solitude which is painful in youth, but delicious in the years of maturity.

I don't try to imagine a personal God; it suffices to stand in awe at the structure of the world, insofar as it allows our inadequate senses to appreciate it.

Adversity introduces a man to himself.

Why do people speak of great men in terms of nationality? Great Germans, great Englishmen? Goethe always protested against being called a German poet. Great men are simply men and are not to be considered from the point of view of nationality, nor should the environment in which they were brought up be taken into account.

When you trip over love, it is easy to get up. But when you fall in love, it is impossible to stand again.

You teach me baseball and I'll teach you relativity...No we must not. You will learn about relativity faster than I learn baseball.