Authentic Thaumaturgy by Issac Bonewits, Pei Bonewitz (1998, Paperback)

I bought this book partly on the basis of the author's reputation, and partly because it looked thinner and easier to handle than his larger work, _Real Magic_.
This book describes how to apply the author's understanding of the methods of occult magic, particularly as practiced by the author himself, to the design of Fantasy Roleplaying Games. For that reason, this book is more likely to be useful to people who are interested in Fantasy Roleplaying Games; people who are NOT so interested should be able to find other books that would be more useful to them.
The physical presentation of the book is eyecatching, using a variety of fonts and many woodcut-style illustrations. The author's sense of humor frequently makes an appearance; and the author's political mindset also becomes quite evident from time to time.
Actual topics include:
Introduction: Clarifications and warnings: this book does not tell you how to do magic in real life.
Chapter 1: The sources of magical characters in fantasy games, including literary sources; and several alternate theories about how magic might work in differently-imagined fantasy worlds.
Chapter 2: Definitions of magic, including the difference between "Theurgy" and "Thaumaturgy"; the relationship between magic and parapsychology; and the nature of ritual.
Chapter 3: Mana (where 1 Mana Point = 1.0 Gramcalorie = 1 millionth of a Kilowatt-Hour); and the major varieties of Psychic Talents: ESP, Hypercognition, Psychokinesis, and Anti-Psi).
Chapter 4: Various ways to distinguish among various types of magic, from "Theurgy vs. Thaumaturgy" to "Active vs. Passive" and "Good vs. Evil," to differences based on types of practitioners and types of effects being sought, even to Colors of Magic, Ranks of Magic Users, and Levels of Spells.
Chapter 5: How to convert theories about magic into numerical attributes for characters in role-playing games: Psi Potential, Psi Talents, Magical Strength, Magical Power, Magical Luck Limit, and Magical Clarity Limit.
Chapter 6: The Laws of Magic: Twenty-six general principles to apply and/or combine when designing magic spells.
Chapter 7: Variability in magical practice: why it doesn't always work the same way every time.
Chapter 8: General rules regarding the casting of magic spells in games: Basic Procedure; the difference between Raw Talent Use and Full Spells; how much Mana is needed; where to get it; Spell decay and failure; and the in-game effects of Anti-Psi.
Chapter 9: Variations on the themes: getting better at rituals through practice, and condensing the components to the same effect; changing spell components; the use of magical devices; planar variation.
Chapter 10: Different varieties of divine (and otherwise) spirits: gods, demons, elementals, etc.
Chapter 11: Religious practice: prayer and magic.
Chapter 12: A whimsical magical adventure embodying the principles previously set forth in the book.