States of Consciousness, a classic by world authority Charles T. Tart, is a basic understanding of how the mind is a dynamic, culturally biased, semi-arbitrary construction and system. A systematic exploration of how and why altered states can come about and their possibilities. As a student of his remarked, "For the first weeks of class I didn't understand what those diagrams were about, but I've realized the book is all about the way my own mind works!" Useful in understanding some of the important ways your mind works before you start altering it.