All these primary impulses, not easily described in words, are the springs of man's actions.

I am satisfied with the mystery of the eternity of life.

It is not so very important for a person to learn facts. For that he does not really need a college. He can learn them from books. The value of an education in a liberal arts college is not learning of many facts but the training of the mind to think something that cannot be learned from textbooks.

A theory can be proved by experiment; but no path leads from experiment to the birth of a theory.

We come now to the question: what is a priori certain or necessary, respectively in geometry (doctrine of space) or its foundations? Formerly we thought everything; nowadays we think nothing. Already the distance-concept is logically arbitrary; there need be no things that correspond to it, even approximately.

The only justification for our concepts and systems of concepts is that they serve to represent the complex of our experiences; beyond this they have not legitimacy.

With fame I become more and more stupid, which of course is a very common phenomenon.