Whats your favourite book and why?

[Kernel Sohcahtoa]

Even though it was a text book, I really enjoyed Larson Calculus; this was a great aid in fulfilling my personal goal of teaching myself calculus (naturally, I had to make use of various supplemental sources, as one source can't cover it all).  It is a comprehensive book that covers differential calculus, integral calculus, basic analytic geometry, and multi-variable calculus/vector calculus.  My favorite areas of study in this book were the following: the u substitution; arc length; line integrals and surface integrals; the concept of curl, Green's theorem, and Stoke's Theorem; parametric equations and polar coordinates (these are cool); integration by parts, trigonometric substitution, and partial fractions; partial derivatives; computing triple integrals , especially via change in coordinates (spherical and cylindrical; these were awesome).  Hence, delving into this book reminded me of how fascinating the world of ideas is and how much I truly appreciate them.