Title: Proofs and Refutations - The Logic of Mathematical Discovery
Author: Imre Lakatos
Short Description: A Plato-esque dialogue between a teacher and his students, aiming to discuss how mathematical discovery happens, how mathematical arguments take form and how mathematical knowledge arises. The discussion is based around the Euler-characteristic, starting off with a concrete conjecture about polyhedra, expanding into the result in full-blown generality through investigation, trial-and-error, the occasional side-track and creative injections as it happens in real life. The book is also sprinkled with mathematical in-jokes, and interesting historical facts about the result. This is a real gem that I keep on my bedside table. Probably aat the higher end of the ++ spectrum.
I'm not sure if I'd get the book for my aunt. It takes mathematical reasoning skills to get though the argument and an understanding of why the questions above are worth answering in the first place. I might get it for a philosophically inclined friend instead.