This is something I missed when I was studying calculus, a few decades ago. Calculus was not difficult for me. I picked it up pretty fast and even applied some of it in other courses in engineering. But I never really grasped the essence. So I am back on a different quest. To understand the relevance of Calculus and applications.
A book like this helps. I think, if you know what it is used for, you can relate to the subject better.
This is from Elementary Calculus: An Infinitesimal Approach, a free e-book. Found it on del.icio.us.
