I have to write a short monograph as an assignment for a course on the philosophy of science. Being a math student, of course I want to opt for something math-related. After some initial ideas which would have needed way too much research, I imagined I could narrow it down to a question which I have always wondered about: is mathematics discovered or created?
I'm thus asking for references to books/papers/quotes/anything which adresses this question. I hope it is not too soft for a math.SE question; I apologize if it is.
In particular, I remember a quote saying something like "Natural numbers were created by God. All else is the work of men", I'd like to know its exact statement and author.
Anything, even if tangentially related, may come in handy. Thank you.