Man must be disciplined, for he is by nature raw and wild.

If it were possible for us to have so deep an insight into a man's character as shown both in inner and in outer actions, that every, even the least, incentive to these actions and all external occasions which affect them were so known to us that his future conduct could be predicted with as great a certainty as the occurrence of a solar or lunar eclipse, we could nevertheless still assert that the man is free.

One who makes himself a worm cannot complain afterwards if people step on him.

The busier we are, the more acutely we feel that we live, the more conscious we are of life.

By a lie a man throws away and, as it were, annihilates his dignity as a man. A man who himself does not believe what he tells another ... has even less worth than if he were a mere thing. ... makes himself a mere deceptive appearance of man, not man himself.

Two things awe me most, the starry sky above me and the moral law within me.

The greatest human quest is to know what one must do in order to become a human being.