I learned many years ago never to waste time trying to convince my colleagues.

As soon as science has emerged from its initial stages, theoretical advances are no longer achieved merely by a process of arrangement. Guided by empirical data, the investigator rather develops a system of thought which, in general, is built up logically from a small number of fundamental assumptions, the so-called axioms. We call such a system of thought a theory. The theory finds the justification for its existence in the fact that it correlates a large number of single observations, and it is just here that the 'truth' of the theory lies.

Adversity introduces a man to himself.

Everybody acts not only under external compulsion but also in accordance with inner necessity.

America is today the hope of all honorable men who respect the rights of their fellow men and who believe in the principle of freedom and justice.

The fear of death is the most unjustified of all fears, for there's no risk of accident for someone who's dead.

I have lived to prove Thoreau's contention that a man is rich in proportion to the number of things which he can afford to let alone.