The title of this book is misleading, as there is nothing mystical in it. I was expecting to read about initiation rites under the Great Pyramid, or a secret transmission by medieval heretics. Instead, I found much solid historical research delving into Tarot's origins.
The most interesting and original part of the book is Huson's description of the trumps' origin in medieval popular culture, especially miracle and morality plays, and depictions of the Dance of the Dead. For instance, he speculates that the Tower came from the stage set for the play the Harrowing of Hell, where the action takes place in a fortified tower with flames blazing from the top, souls peering out through barred openings, and the Devil looming over it all. By the mid-16th century, these plays were no longer performed. Tarot had lost its moorings in traditional medieval culture, and was being influenced by popular printed material like calendars, almanacs and horoscopes.
The heart of the book is his discussion of individual cards, showing possible origins for the images and their divinatory meanings. He lists meanings attributed to each card by cartomancers and occultists from the mid 18th to the early 20th centuries: an anonymous 1750 Bologna manuscript, deGebelin, deMellet, Etteilla, Eliphas Levi, Paul Christian, Mathers (co-founder of the Golden Dawn), A. E. Waite writing as Grand Orient in 1889, and Waite in the Pictorial Key to Tarot of 1909. Huson also provides descriptions of the astrological decans from the medieval work Picatrix, which the Golden Dawn rather awkwardly grafted onto Etteilla's card meanings to formulate what has become the basis for modern divinatory meanings. The discussion of each card is accompanied by Huson's line drawings of the Rider-Waite-Smith and Conver Tarot de Marseilles decks, as well as related medieval art, making it a very nice reference.
The book summarizes how 18th and 19th century occultists influenced Tarot. I was happy to see it give the vastly underrated Etteilla his due. Etteilla invented modern cartomancy using spreads; and his card meanings are the underpinning of the Rider-Waite-Smith system, which has so heavily influenced contemporary Anglo-American tarot. Several spreads invented by Etteilla and 19th century cartomancers make this book especially useful to people interested in traditional card reading methods.
Huson's discussion of the origins of the four suits and their symbols is the least convincing part of the book. He summarizes the evolution of playing cards from the abstract, medieval Egyptian Mamluk cards into Italian, German and French suit symbols. Then he speculates, with weak evidence, that these symbols may have roots in pre-Islamic Persian culture and Sufism, or possibly traditional allegories of the Virtues. He also gives some speculative theories about the origin of court cards in medieval literature.
Scattered throughout are intriguing nuggets of historical speculation on the origin of card images. For instance, Huson traces the 7 of Swords image in the RWS deck to the 15th century Sola Busca deck, and then back to an incident in a medieval romance where devious means were used to steal some swords from Charlemagne and his knights.
I highly recommend this book for anyone interested in tarot's roots. It isn't comprehensive, but it includes topics that get little or no coverage in general discussions of tarot history. If you ever wondered where our card meanings come from, his comparison of divinatory meanings from various sources is a gold mine. For people interested in traditional cartomancy, this book is the best source we have in English for pre-Golden Dawn card meanings and spreads.