Structure and Interpretation of Computer Programs (Hal Abelson, Jerry Sussman and Julie Sussman; MIT Press, 1984, 1996; ISBN 0-262-01153-0), an excellent computer science text used in introductory courses at MIT. So called because of the wizard on the jacket. One of the bibles of the LISP/Scheme world. Also, less commonly, known as the Purple Book. Now available on the http://mitpress.mit.edu/sicp/