Reading Chinese Astrology as History

Ho Peng Yoke worked on Chinese science for half a century, collaborated with Joseph Needham on the great survey of Chinese science and civilisation, and later directed the institute at Cambridge that carries Needham name. His book on Chinese mathematical astrology is the reason the atlas can describe several Chinese divinatory systems without relying on practitioner manuals, because it treats them as historical techniques with datable sources, named authors and reconstructible procedures.

The systems it covers are the three that Chinese tradition groups together as the arts of the cosmic boards. Taiyi tracks a supreme unity moving through palaces on a fixed schedule and was used for questions about dynasties and large events. Dunjia works with a set of stems and branches distributed over a board with a shifting arrangement and was applied to military and practical timing. Liuren uses a rotating heaven plate above a fixed earth plate to produce a figure read for the moment of the question. All three were, at various times, restricted knowledge, taught in the state astronomical office and forbidden to private study, because a technique for predicting the fate of a dynasty is a political object as much as a religious one.