Religious ideas have sprung from the same need as all the other achievements of culture: from the necessity for defending itself against the crushing supremacy of nature.

The religions of mankind must be classed among the mass-delusions of this kind. No one, needless to say, who shares a delusion ever recognizes it as such.

It is a mistake to believe that science consists in nothing but conclusively proved propositions, and it is unjust to demand that it should. It is a demand made by those who feel a craving for authority in some form to replace the religious catechism by something else, even a scientific one.

The inclination to aggression constitutes the greatest impediment to civilization.

I have often felt as though I had inherited all the defiance and all the passions with which our ancestors defended their Temple and could gladly sacrifice my life for one great moment in history. And at the same time I always felt so helpless and incapable of expressing these ardent passions even by a word or a poem.

It is impossible to overlook the extent to which civilization is built upon a renunciation of instinct.

It might be said of psychoanalysis that if you give it your little finger it will soon have your whole hand.