I know that I am intelligent, because I know that I know nothing.

Let us permit nature to have her way. She understands her business better than we do.

I am fond of pigs. Dogs look up to us. Cats look down on us. Pigs treat us as equals.

I'm not as famous as Stephen Hawking, but certainly in the U.S., I have a very high profile for a scientist. It is an awesome responsibility, one that I don't shoulder lightly.

I always bring out the best in men I fight, but Joe Frazier, I'll tell the world right now, brings out the best in me. I'm gonna tell ya, that's one helluva man, and God bless him.