If you can't explain it simply, you don't understand it well enough.

Make everything as simple as possible, but not simpler.

Certainly there are things worth believing. I believe in the brotherhood of man and the uniqueness of the individual. But if you ask me to prove what I believe, I can't. You know them to be true but you could spend a whole lifetime without being able to prove them. The mind can proceed only so far upon what it knows and can prove. There comes a point where the mind takes a leap—call it intuition or what you will—and comes out upon a higher plane of knowledge, but can never prove how it got there. All great discoveries have involved such a leap.

Arrows of hate have been aimed at me too, but they have never hit me, because somehow they belonged to another world with which I have no connection whatsoever.

I don't teach my students, I provide the circumstances in which they can learn.

Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.

The thinking it took to get us into this mess is not the same thinking that is going to get us out of it.