I believe there is no source of deception in the investigation of nature which can compare with a fixed belief that certain kinds of phenomena are IMPOSSIBLE.

No more fiendish punishment could be devised, were such a thing physically possible, than that one should be turned loose in society and remain absolutely unnoticed.

The good we do today becomes the happiness of tomorrow.

To spend life for something which outlasts it.

The more rational statement is that we feel sorry because we strike, afraid because we tremble, and not that we cry, strike, or tremble because we are sorry, angry, or fearful as the case may be.

The history of philosophy is to a great extent that of a certain clash of human temperaments.

The war-function has grasped us so far; but the constructive interests may some day seem no less imperative, and impose on the individual a hardly lighter burden.