John von Neumann

Young man, in mathematics you don’t understand things. You just get used to them.

Any one who considers arithmetical methods of producing random digits is, of course, in a state of sin. For, as has been pointed out several times, there is no such thing as a random number.

A large part of mathematics which becomes useful developed with absolutely no desire to be useful, and in a situation where nobody could possibly know in what area it would become useful.

If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is.