There are two principles inherent in the very nature of things, recurring in some particular embodiments whatever field we explore - the spirit of change, and the spirit of conservation. There can be nothing real without both. Mere change without conservation is a passage from nothing to nothing. . . . Mere conservation without change cannot conserve. For after all, there is a flux of circumstance, and the freshness of being evaporates under mere repetition.

There is no more common error than to assume that, because prolonged and accurate mathematical calculations have been made, the application of the result to some fact of nature is absolutely certain.

Mathematics, in its widest significance, is the development of all types of formal, necessary, deductive reasoning.

Life is an offensive, directed against the repetitious mechanism of the Universe.

For successful education there must always be a certain freshness in the knowledge dealt with. It must be either new in itself or invested with some novelty of application to the new world of new times. Knowledge does not keep any better than fish. You may be dealing with knowledge of the old species, with some old truth; but somehow it must come to the students, as it were, just drawn out of the sea and with the freshness of its immediate importance.

Our reasonings grasp at straws for premises and float on gossamers for deductions.

The future belongs to those who can rise above the confines of the earth.