What is the difference between method and device? A method is a device which you use twice.

There are many questions which fools can ask that wise men cannot answer.

Analogy pervades all our thinking, our everyday speech and our trivial conclusions as well as artistic ways of expression and the highest scientific achievements.

It is better to solve one problem five different ways, than to solve five problems one way.

The result of the mathematician's creative work is demonstrative reasoning, a proof; but the proof is discovered by plausible reasoning, by guessing.

I am too good for philosophy and not good enough for physics. Mathematics is in between.

If there is a problem you can't solve, then there is an easier problem you can't solve: find it.