Theorem 23, Monas Hieroglyphica (1564). This theorem is one of 24 contained in the work Monas Hieroglyphica by Welsh astrologer John Dee (1527-1608). An example of western Hermeticism and written in a mystical state, it revealed esoteric secrets in astronomy, alchemy, music, mathematics, linguistics, mechanics, and optics. Theorem 23 was the culmination of the book, which explained in part the derivation of the mystical symbol shown here, Dee's Monad. The symbol represented Dee's mystical vision of a unified cosmos, though much of what he wrote remains unexplained due to lost oral traditions.