You cannot be wise without some basis of knowledge, but you may easily acquire knowledge and remain bare of wisdom.

Algebra is the intellectual instrument which has been created for rendering clear the quantitative aspects of the world.

I always feel that I have two duties to perform with a parting guest: one, to see that he doesn't forget anything that is his; the other, to see that he doesn't take anything that is mine.

The art of progress is to preserve order amid change, and to preserve change amid order. Life refuses to be embalmed alive. The more prolonged the halt in some unrelieved system of order, the greater the crash of the dead society.

The race that does not value trained intelligence is doomed.

In a living civilization there is always an element of unrest, for sensitiveness to ideas means curiosity, adventure, change. Civilized order survives on its merits and is transformed by its power of recognizing its imperfections.

The paradox is now fully established that the utmost abstractions are the true weapons with which to control our thought of concrete fact.