Jealous is every virtue of the others, and a dreadful thing is jealousy. Even virtues may succumb by jealousy.

Freedom is the will to be responsible for ourselves.

At the beginning of a marriage ask yourself whether this woman will be interesting to talk to from now until old age. Everything else in marriage is transitory: most of the time is spent in conversation.

I fly in dreams, I know it is my privilege, I do not recall a single situation in dreams when I was unable to fly. To execute every sort of curve and angle with a light impulse, a flying mathematics - that is so distinct a happiness that it has permanently suffused my basic sense of happiness.

Wherever primitive man put up a word, he believed he had made a discovery. How utterly mistaken he really was! He had touched a problem, and while supposing he had solved it, he had created and obstacle to its solution. Now, with every new knowledge we stumble over flint-like and petrified words and, in so doing, break a leg sooner than a word.

I understand by 'freedom of spirit' something quite definite - the unconditional will to say No, where it is dangerous to say No.

That which an age considers evil is usually an unseasonable echo of what was formerly considered good - the atavism of an old ideal.