One can't teach a cat not to catch birds

An expert is a person who has few new ideas; a beginner is a person with many.

The real problem is in the hearts and minds of men. It is not a problem of physics but of ethics. It is easier to denature plutonium than to denature the evil spirit of man.

It is only men who are free, who create the inventions and intellectual works which to us moderns make life worth while.

The individual must not merely wait and criticize, he must defend the cause the best he can. The fate of the world will be such as the world deserves.

James Clerk Maxwell's [work is the] most profound and the most fruitful.

The whole of science is nothing more than a refinement of everyday thinking.