The most important method of education always has consisted of that in which the pupil was urged to actual performance.

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

I do not believe that a moral philosophy can ever be founded on a scientific basis. … The valuation of life and all its nobler expressions can only come out of the soul’s yearning toward its own destiny. Every attempt to reduce ethics to scientific formulas must fail. Of that I am perfectly convinced.

I'm no more intelligent than the next guy. I'm just more curious.

What is this frog and mouse battle among the mathematicians?

Everything is energy and that’s all there is to it.

I now see the necessity of a beginning.