“Mathematics is” quotes

For at least six years, I've been collecting quotes about what mathematics is. Here are some of them. “... mathematics is not an empirical science, ...” (Von Neumann, The Mathematician ) “Mathematics is not a deductive science—that's a cliché.” (Halmos, I want to be a mathematician ) “Pure mathematics is, in its way, the poetry of logical ideas.” (Einstein, epitaph for Noether) “... mathematics is…