Nonmathematical people sometimes ask me, You know math, huh? Tell me something I've always wondered, What is infinity divided by infinity? I can only reply, The words you just uttered do not make sense. That was not a mathematical sentence. You spoke of 'infinity' as if it were a number. It's not. You may as well ask, 'What is truth divided by beauty?' I have no clue. I only know how to divide numbers. 'Infinity,' 'truth,' 'beauty'—those are not numbers.

Prime Obsession: Bernhard Riemann and the Greatest Unsolved Problem in Mathematics (2003)