With a strong emphasis on primary sources, Heavenly Numbers explores the Chinese system of astronomy and the emphasis Chinese rulers placed on the preciseness of the system. An attempt to make this text understandable to both the layperson and to the scholar is apparent throughout in the reiteration and discussion of concepts as a narrative rather than a series of concise definitions.
Heavenly Numbers begins with an introduction to the Chinese astronomy system and, more importantly for this material, the implications that a precise calendar had on a ruling dynasty. Through a series of chapters, the reader is introduced to Chinese mathematicians who are novel contributors to the accuracy of the calendar system. Although these mathematician-astronomers are “side characters” to the ruling party, Cullen makes it obvious that without their key contributions — including tracking stars, planets, and pinning down equinoxes and eclipses — the connection that Chinese dynasties made between emperors and gods would have been more tenuously accepted by the population as a whole. This is evident especially in the transition between dynasties: Cullen discusses how these transitionary periods were often accompanied by changes to the position of master astronomer and occasionally, the accepted calendar itself.
Cullen guides the reader through the Chinese system in precise detail with references to source documents and incorporation of Chinese characters throughout the text. Footnotes pepper each page with tidbits of information, clarification, or references to source documents. Although helpful, this reviewer did find the sheer amount of side-information distracting and would rather see these comments in an endnote for each chapter. Regardless, Heavenly Numbers is an enlightening glimpse into Eastern mathematics and astronomy and the reader will finish the book with an appreciation of the depth of the connection between the two fields.
Megan Sawyer is an associate professor of mathematics at Southern New Hampshire University in Manchester, NH.