Man, surrounded by facts, permitting himself no surprise, no intuitive flash, no great hypothesis, no risk, is in a locked cell. Ignorance cannot seal the mind and imagination more securely.

Infinite striving to be the best is man's duty; It is its own reward. Everything else is in god's hands. It's not that I'm so smart, it's just that I stay with problems longer.

There is, however, one other human right which is infrequently mentioned but which seems to be destined to become very important: this is the right, or the duty, of the individual to abstain from cooperating in activities which he considers wrong or pernicious.

You teach me baseball and I'll teach you relativity...No we must not. You will learn about relativity faster than I learn baseball.

The world is not full of evil because of those who do wrong. It is full of evil because of those who do nothing.

... it is a welcome symptom in an age which is commonly denounced as materialistic, that it makes heroes of men whose goals lie wholly in the intellectual and moral sphere.

The sceptic will say, 'It may well be true that this system of equations is reasonable from a logical standpoint, but this does not prove that it corresponds to nature.' You are right, dear sceptic. Experience alone can decide on truth.