The full title of the book is "The Essential Tarot - Unlocking the Mystery" and it is the second book of Vincent Pitisci after his first one "The Genius of the Tarot". The writer is a professional tarot reader in Chicago and he teaches cartomancy in classes and online for free through youtube. He is one of the few tarot readers who openly speaking about the importance of Tarot de Marseille. He uses a system based on numerology for interpreting the minor arcana, transcending all image differences among the different tarot systems. In his books, he uses the RWS tarot, because it is more accessible to people nowadays. Let's see the essence of the book.
He starts by describing what is creative thinking and how it is related to divination. He provides a logical explanation on the question of why tarot works and he does that in a good way. He fills all the gaps between tarot divination and conceptual blending. Next, he explains each card with a variety of keywords, which are easy to work with card combinations, yet I don't believe that this is the best idea for a beginner to start learning the cards. Anyway, he does a very good job with keywords. I agree with most of them. They are mostly based on RWS and numerology. Then we have three card spreads with examples. The 3-cards spread, the Pitisci's variation of the Celtic Cross spread and the gypsy spread. The variation of Pitisci is perfect for 3 3-cards combinations, very appropriate for TdM readings. The gypsy spread he presents is useful for analyzing a situation, not much for predicting the future. He doesn't use reversals, because he uses many cards in a spread. Pitisci considers the application of the cards more important than just knowing the meaning of the cards. This makes his book very practical. His examples are usefully explained, not much with text, but with a good organization with images and small paragraphs.
He devotes 164 pages for card meanings and 73 pages to card spreads. In his first book, he follows the same organization, but I think that The Essential Tarot is more successful due to the use of keywords. I recommend the first one for reading more examples of card spreads and the 4 winds spread, that is not included in The Essential Tarot. His writing style is similar to the way he speaks, but with less humor. Small paragraphs, small sentences, to the point. He doesn't overwhelm the reader with useless information and he remains consistent on the system he describes. Personally, I would prefer to read two pages of text for each card, than read keywords, but it works well for divination and it is another helpful method of learning the card meanings. This book is a good choice.
Theurgy and Philosophy are two different methods which lead to the union with God.