Mathematics has the completely false reputation of yielding infallible conclusions. Its infallibility is nothing but identity. Two times two is not four, but it is just two times two, and that is what we call four for short. But four is nothing new at all. And thus it goes on and on in its conclusions, except that in the higher formulas the identity fades out of sight.
Source: J. R. Newman (ed.) The World of Mathematics, New York: Simon and Schuster, 1956, p. 1754.
Contributed by: Zaady