Though there are a number of well-written works on Chinese divination, there are none that deal with the three sophisticated devices that were employed by the Chinese Astronomical Bureau in the eleventh century and for hundreds of years thereafter. Chinese experts applied the methods associated with these devices to both weather forecasting and to the interpretation of human affairs.

Hidden by a veil of secrecy, these methods have always been relatively little known other than by their names. The first work in any language to explore these three methods, known as sanshi (three cosmic boards), this book sheds light on a topic which has been shrouded in mystery for centuries, having been kept secret for many years by the Chinese Astronomical Bureau.