Comments and mentions from HN threads:
Ask HN: Books Like 'Calculus Made Easy'?
jwdunne: Interesting book and starts off with a bit more of the fundamentals.
Ask HN: Are there books for mathematics like Feynman's lectures on physics?
jordigh: It's a wonderful book, written in a very engaging style, and it shows you how mathematicians think and how they play. It shows you why we have proofs, why things go wrong, and all that had to happen before we came up with a definition of derivatives and integrals that we're happy with (and of course, all of the things we can do with our newfound definitions).
Mugwort: I would like to add that learning calculus properly is of the utmost importance. It's no exaggeration when I say that this is unquestionably the single best, most profitable action you can take. Any one of these books can change your life.