Here are some very good math quotes listed on Jon Pakianathan's web page.
"You spend 30 minutes with a beautiful girl, it seems like a moment. You spend a moment sitting on a hot stove, it seems like 30 minutes." (Giving the most practical, understandable explanation of the Theory of Relativity; how time can expand or contract.)
"The secret to creativity is knowing how to hide your sources."
"If we knew what it was we were doing, it would not be called research, would it?"
"If World War III is fought with nuclear weapons, then World War IV will be fought with stones."
"There is a race between mankind and the universe. Mankind is trying to build bigger, better, faster, and more foolproof machines. The universe is trying to build bigger, better, and faster fools. So far the universe is winning."
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
"Generations to come, it may be, will scarce believe that such a one as this ever in flesh and blood walked upon this earth!" (Referring to Mahatma Gandhi after Gandhi was assassinated.)
The difference between stupidity and genius is that genius has its limits.