I've been relearning some math that I forgot so that I can learn general relativity (just for fun), and this was what I worked through to brush off my calculus.

I've been relearning some math that I forgot so that I can learn general relativity (just for fun), and this was what I worked through to brush off my calculus. Really great book, and far superior to anything else I've seen. There seem to be two approaches to calculus: dumbed down and mechanical (pretty much any modern non-math major text) or abstract and proof based (something like Spivak). This first group of books takes pages and pages to get to the point and provides no understanding of why calculus works. The second book is just too hard for a normal person who doesn't already know the subject pretty well and who is trying to teach themselves. Calculus Made Easy fits right in the sweet spot. While it isn't entirely rigorous, it does justify everything clearly enough that you can see that the manipulations you're learning are valid. At the same time, it always remains focused on calculations, so you don't get lost in abstractions.