Philosophers are people who know less and less about more and more, until they know nothing about everything. Scientists are people who know more and more about less and less, until they know everything about nothing.

Hatred of humanity and love of animals make a very bad combination.

The instinctive need to be the member of a closely knit group fighting for common ideals may grow so strong that it becomes inessential what these ideals are.

Historians will have to face the fact that natural selection determined the evolution of cultures in the same manner as it did that of species.

I believe-and human psychologists, particularly psychoanalysts should test this-that present-day civilized man suffers from insufficient discharge of his aggressive drive. It is more than probable that the evil effects of the human aggressive drives, explained by Sigmund Freud as the results of a special death wish, simply derive from the fact that in prehistoric times intra-specific selection bred into man a measure of aggression drive for which in the social order today he finds no adequate outlet.

Man has been driven out of the paradise in which he could trust his instincts.

The neuro-physiological organization which we call instinct functions in a blindly mechanical way, particularly apparent when its function goes wrong.