A man who is convinced of the truth of his religion is indeed never tolerant. At the least, he is to feel pity for the adherent of another religion but usually it does not stop there. The faithful adherent of a religion will try first of all to convince those that believe in another religion and usually he goes on to hatred if he is not successful. However, hatred then leads to persecution when the might of the majority is behind it.

The state is made for man, not man for the state.... That is to say, the state should be our servant and not we its slaves

To the extent math refers to reality, we are not certain to the extent we are certain, math does not refer to reality.

Those who manage their way into a crisis are not necessarily the right people to manage their way out of a crisis

I must seem like an ostrich who forever burries its head in the relativistic sands in order not to face the evil quanta.

The relativity principle in connection with the basic Maxwellian equations demands that the mass should be a direct measure of the energy contained in a body; light transfers mass. With radium there should be a noticeable diminution of mass. The idea is amusing and enticing; but whether the Almighty is laughing at it and is leading me up the garden path -- that I cannot know.

The feeling for what ought and ought not to be grows and dies like a tree, and no fertilizer of any kind will do much good. What the individual can do is give a fine example, and have the courage to firmly uphold ethical convictions in a society of cynics. I have for a long time tried to conduct myself this way, with varying success.