Moral indignation is one of the most harmful forces in the modern world, the more so as it can always be diverted to sinister uses by those who control propaganda.

Morality in sexual relations, when it is free from superstition, consists essentially in respect for the other person, and unwillingness to use that person solely as a means of personal gratification, without regard to his or her desires.

Beware the man of the single book

It is undesirable to believe a proposition when there is no ground whatever for supposing it true

Even in the most purely logical realms, it is insight that first arrives at what is new.

I don't like the spirit of socialism - I think freedom is the basis of everything.

One of the symptoms of approaching nervous breakdown is the belief that one's work is terribly important, and that to take a holiday would bring all kinds of disaster. If I were a medical man, I should prescribe a holiday to any patient who considered his or her work important.