We can invent as many theories we like, and any one of them can be made to fit the facts. But that theory is always preferred which makes the fewest number of assumptions.

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

I must be willing to give up what I am in order to become what I will be.

I now see the necessity of a beginning.

Anybody who really wants to abolish war must resolutely declare himself in favor of his own country's resigning a portion of sovereignty in place of international institutions.

The physicist's greatest tool is his wastebasket.

The daily struggle does not arise from a purpose or a program, but from an immediate need.