I always found I was in the best of company, alone.

The indifference, callousness and contempt that so many people exhibit toward animals is evil first because it results in great suffering in animals, and second because it results in an incalculably great impoverishment of the human spirit.

It stands to the everlasting credit of science that by acting on the human mind it has overcome man's insecurity before himself and before nature.

No fairer destiny could be allotted to any physical theory than that it should of itself point out the way to the introduction of a more comprehensive theory, in which it lives on as a limiting case.

Yes, we now have to divide up our time like that, between politics and our equations. But to me our equations are far more important, for politics are only a matter of present concern. A mathematical equation stands forever.

A life directed chiefly toward the fulfillment of personal desires will sooner or later always lead to bitter disappointment.

In my experience, the best creative work is never done when one is unhappy.