"The Pictorial Key to the Tarot is A. E. Waite's influential guide to Tarot symbolism, published in England in 1910 in conjunction with the Rider-Waite-Smith deck. While Waite was an occultist, he was very concerned with the accuracy of the symbols he used for his deck, and he did much research into the traditions, interpretations, and history behind the cards.
The book (which Waite himself called "a monograph") consists of three parts.
-Part I, "The Veil and Its Symbols", is a short overview of the traditional symbols associated with each card, followed by a history of the Tarot. Waite dismissed as baseless the belief that the Tarot was Egyptian in origin, and noted that no evidence of the cards exists prior to the 15th century.
-Part II, "The Doctrine of the Veil", contains 78 black and white plates of the Rider-Waite-Smith deck, and a discussion of the unique symbols chosen for each card. Waite drew upon the earlier Tarot of French occultist Eliphas Levi, at times retaining his changes to the traditional deck (as with the Chariot card, which both Waite and Levi picture being drawn by two sphinx, instead of horses), at other times criticizing him (as with the Hermit card, which Waite thought Levi misinterpreted).
-Part III, "The Outer Methods of the Oracles", concerns matters of divination with the cards, including a description of the famous Celtic Cross Tarot layout, which the book helped popularize." (Quote from wikipedia.org)