Conviction is a good motive, but a bad judge.

Man would indeeded be in a poor way if he had to be restrained by fear of punishment and hope of reward after death.

A country cannot simultaneously prepare and prevent war. I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. The distinctions separating the social classes are false; in the last analysis they rest on force.

Even a fool is wise after an event.

I never allow myself to become discouraged under any circumstances. The three great essentials to achieve anything worthwhile are first, hard work, second, stick-to-ittiveness, third, common sense.

What is this frog and mouse battle among the mathematicians?

I want to know all Gods thoughts; all the rest are just details.