This book is an invaluable exposition of a venerable and little known spiritual science, illustrated by original scholarly translations of primary sources from early times. It is neither a popular self help book nor is it a textbook per se. The concept of the NAFS and the states and stations of spiritual and material existence are elucidated very clearly for the western reader and these tools and concepts exist in the mystical teachings of all traditions under various names. For instance, Christian Orthodox mystical practice has much the same diagrammatic structure. This book is all essence and no filler, it is not a mass market paperback. There are a lot of books out there purportedly about Sufism that are really about the authors ego (and wallet). Not this one! The authentic knowledge contained in this slim volume is prerequisite for study and practice of the spiritual path.