The complete article on the 15 card "Thoth" Tarot spread appears in Stella Tenebrae – Journal of Hermetic Magick, Volume One No. 2 (autumn equinox 2012). Here is the Tarot spread with a description of the card positions.
The 15 card Tarot spread is sometimes called the "Thoth" Tarot spread, as it seems to have been devised by the publisher of some early editions of the Crowley-Harris Thoth deck. The advantage of this spread is that cards are read in sets of three, so the elemental dignities of the Tarot can be applied. The method of laying out the cards is very attractive, since a widdershins spiral is formed, outward from the centre. Numerically, there is a strong relationship with the Pentagram.
The three centre cards represent the question and the questioner. The upper left cards are a future development of the upper right cards, if the two sets agree. If not, the upper right cards represent the course of action the querent would naturally take, and the upper left cards an alternative course of action that changes the future outcome. The lower left cards represent the attitude of the querent or psychological basis of the question. The lower right cards represent destiny, spiritual forces or karma that is beyond the control of the querent; as such, these three cards are to be regarded as advice.
© Oliver St. John 2012