The main task of the spirit is to free man from his ego.

Even on the most solemn occasions I got away without wearing socks and hid that lack of civilization in high boots

We must learn the difficult lesson that the future of Mankind will only be tolerable when our course, in world affairs as in others, is based upon justice and law rather than the threat of naked power.

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.

If I give you a pfennig, you will be one pfennig richer and I'll be one pfennig poorer. But if I give you an idea, you will have a new idea, but I shall still have it too.

The feeling for what ought and ought not to be grows and dies like a tree, and no fertilizer of any kind will do much good. What the individual can do is give a fine example, and have the courage to firmly uphold ethical convictions in a society of cynics. I have for a long time tried to conduct myself this way, with varying success.

To obtain an assured favorable response from people, it is better to offer them something for their stomachs instead of their brains.