Richard P. Feynman Quotes about Mathematics

Mathematics is not just a language. Mathematics is a language plus reasoning.
"The Character of Physical Law". Book by Richard P. Feynman, 1965.
Richard P Feynman (2014). “Surely You're Joking Mr Feynman: Adventures of a Curious Character as Told to Ralph Leighton”, p.84, Random House
Richard P. Feynman (2014). “QED: The Strange Theory of Light and Matter”, p.63, Princeton University Press