The scientist knows very well that he is approaching ultimate truth only in an asymptotic curve and is barred from ever reaching it; but at the same time he is proudly aware of being indeed able to determine whether a statement is a nearer or a less near approach to the truth.

All the advantages that man has gained from his ever-deepening understanding of the natural world that surrounds him, his technological, chemical and medical progress, all of which should seem to alleviate human suffering... tends instead to favor humanity's destruction.

In nature we find not only that which is expedient, but also everything which is not so inexpedient as to endanger the existence of the species.

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.

We do not take humor seriously enough.

It is a good morning exercise for a research scientist to discard a pet hypothesis every day before breakfast. It keeps him young.