The really valuable method of thought to arrive at a logically coherent system is intuition.

Imagination is the most powerful force in the universe.

The mathematician knows some things, no doubt, but not those things one usually wants to get from him.

It is true that my parents were worried because I began to speak fairly late, so that they even consulted a doctor. I can't say how old I was - but surely not less than three.

A problem defined, is a problem half solved.

As long as I have any choice in the matter, I shall live only in a country where civil liberty, tolerance and equality of all citizens before the law prevail.

But their intervention makes our acts to serve ever less merely the immediate claims of our instincts.