Reality is merely an illusion, albeit it a very persistent one.

... one does people the best service by giving them some elevating work to do and thus indirectly elevating them.

You do not really understand something unless you can explain it to your grandmother.

Everything should be as simple as possible, but no simpler.

The important thing is not to stop questioning. Curiosity has its own reason for existing. One cannot help but be in awe when he contemplates the mysteries of eternity, of life, of the marvelous structure of reality. It is enough if one tries merely to comprehend a little of this mystery every day. Never lose a holy curiosity.

The State is made for man, not man for the State.

Science without religion is lame, religion without science is blind.

I don't know what will be used in the next world war, but the fourth will be fought with stones.

The ordinary objects of human endeavour - property, outward success, luxury have always seemed to me contemptible ... The ideals which have lighted me on my way and time after time given me new courage to face life cheerfully, have been Truth, Goodness, and Beauty.

The important thing is not to stop questioning.