“To understand why 666 is a magick number of the Sun, we first refer to the Qabaliistic diagram the Tree of Life and discover that the sphere of the Sun is the sixth Sephira, Tiphareth. A kamea of the Sun is a square composed of 36 squares (6×6). The numbers 1-36 are then arranged in such a way that every row and column add to the same number. The number is 111, and the sum of all squares is 666."
-The Magick of Aleister Crowley by Lon Milo DuQuette