You have to learn the rules of the game. And then you have to play better than anyone else.

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.

I have reached the conviction that the abolition of the death penalty is desirable. Reasons: 1) Irreparability in the event of an error of justice, 2) Detrimental moral influence of the execution procedure on those who, whether directly or indirectly, have to do with the procedure.

Nationalism is an infantile disease. It is the measles of mankind.

Chess holds its master in its own bonds, shackling the mind and brain so that the inner freedom of the very strongest must suffer.

Berlin is the place to which I am most closely bound by human and scientific ties.

Princeton is a wonderful little spot. A quaint and ceremonious village of puny demigods on stilts.