Next year I'm going to begin studying physics as freshman and this summer I was thinking about studying Calculus on my own. Would Spivak be feasible as an introduction to calculus? I'm in Pre-Calculus right now and find it pretty easy (though I know that is not necessarily any indicator of calculus ability). I want to study Spivak because I want to see the more theoretical side of math, something I have no experience with. If it's not really feasible though, what book would you recommend, something like Stewart? The university I'm going to next year uses Hughes-Hallet...the reviews on Amazon.com basically say it's one of the worst calculus textbooks; another reason I feel like studying over the summer is a good idea.