Mathematics is only the art of saying the same thing in different words.

The chicken noticed that the farmer came every day to feed it. It predicted that the farmer would continue to bring food every day. Inductivists think that the chicken had "extrapolated" its observations into a theory, and that each feeding time added justification to that theory. Then one day the farmer came and wrung the chicken's neck. This inductively justifies the conclusion that induction cannot justify any conclusion.

A man who has once perceived, however temporarily and however briefly, what makes greatness of soul, can no longer be happy if he allows himself to be petty, self-seeking, troubled by trivial misfortunes, dreading what fate may have in store for him. The man capable of greatness of soul will open wide the windows of his mind, letting the winds blow freely upon it from every portion of the universe.

To the primitive mind, everything is either friendly or hostile; but experience has shown that friendliness and hostility are not the conceptions by which the world is to be understood.

It is a waste of energy to be angry with a man who behaves badly, just as it is to be angry with a car that won't go.

To discover a system for the avoidance of war is a vital need of our civilisation.

The most savage controversies are about matters as to which there is no good evidence either way.