Structure and Interpretation of Computer Programs by Abelson and Sussman, for the uninitiated.

It's one of the best introductions to basic and advanced (and then even more advanced) programming there is. This book, along with a series of "The Little Schemer", "The Seasoned Schemer" and "How to design programs" use Scheme as a language, and Racket makes it particularly easy to follow them by providing special environments (#langs) crafted for them.