Theorem 13, 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 13 concerns the planetary alchemy. The diagram shows the "monadic anatomy [of the] realm of astronomia inferior". Seven numbered symbols and the Sun are merged to form the central shaded figure. Symbols include Mercury, Venus, Saturn, the Moon, and the Sun.