One of the chief triumphs of modern mathematics consists in having discovered what mathematics really is.

The first step in a fascist movement is the combination under an energetic leader of a number of men who possess more than the average share of leisure, brutality, and stupidity. The next step is to fascinate fools and muzzle the intelligent, by emotional excitement on the one hand and terrorism on the other.

Marriage is for women the commonest mode of livelihood, and the total amount of undesired sex endured by women is probably greater in marriage than in prostitution.

The opposition of instinct and reason is mainly illusory. Instinct, intuition, or insight is what first leads to the beliefs which subsequent reason confirms or confutes; but the confirmation, where it is possible, consists, in the last analysis, of agreement with other beliefs no less instinctive. Reason is a harmonizing, controlling force rather than a creative one. Even in the most purely logical realms, it is insight that first arrives at what is new.

I have come to realize that an early symptom of approaching mental illness is the belief that one's work is terribly important. If you consider your work very important you should take a day off.

It will be said that the joy of mental adventure must be rare, that there are few who can appreciate it, and that ordinary education can take no account of so aristocratic a good. I do not believe this. The joy of mental adventure is far commoner in the young than in grown men and women. ...It is rare in later life because everything is done to kill it during education.

It is the things for which there is no evidence that are believed with passion.