Pure mathematics is, in its way, the poetry of logical ideas. ... [By seeking] logical beauty spiritual formulas are discovered necessary for the deeper penetration into the laws of nature.

Without "ethical culture", there is no salvation for humanity.

Put your hand on a hot stove for a minute and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute.

This has been done elegantly by Minkowski; but chalk is cheaper than grey matter, and we will do it as it comes.

Don't listen to the person who has the answers; listen to the person who has the questions.

A theory is the more impressive the greater the simplicity of its premises is, the more different kinds of things it relates, and the more extended its area of applicability.

God is a scientist, not a magician.