Tong Shu

The Tong Shu (the "book that knows all," commonly the Chinese almanac) is the annual compendium of calendrical and divinatory knowledge used across the Chinese world to select auspicious days and hours for the actions of life and to avoid inauspicious ones. It is one of the most widely owned and consulted books in Chinese popular culture, historically found in a great many households, and it addresses the practical question of timing: on which day one should marry, hold a funeral, move house, open a business, sign a contract, begin building, travel, or undertake any significant act, and which days are unfavorable for each. It compiles an extraordinary density of traditional knowledge: the lunar and solar calendars and their correlation, the twenty-four solar terms that mark the agricultural year, the sexagenary cycle of the "heavenly stems and earthly branches," the auspicious and inauspicious associations of each day, astrological and feng shui data, guidance drawn from the I Ching and from systems of fate-calculation, along with charms, festival dates, and much folk lore.

The selection of auspicious dates it enables is a distinct traditional art (sometimes called ze ri, "choosing the day"). As a living practice, consulting the almanac, or a specialist who uses it, before weddings, funerals, and other important undertakings remains common across China and the Chinese diaspora, embodying the deep-rooted conviction that the timing of an action, in harmony with the cosmic calendar, bears on its success.

The Chinese almanac is not simply a book of auspicious days. For most of imperial history the issuing of the calendar was a sovereign act, reserved to the throne, and its distribution through the empire was one of the ways a dynasty asserted that it held the mandate. Producing an unauthorised calendar was accordingly a serious offence, punished severely under several dynasties.

That gave the astronomical bureau responsible for computing it an unusual standing, and it explains an episode that would otherwise be baffling. From the seventeenth century Jesuit missionaries were appointed to direct the imperial astronomical bureau, because their calculations of eclipses proved more accurate than those of their rivals, and a dynasty whose legitimacy rested partly on getting the calendar right had a practical reason to employ them. The arrangement lasted well over a century and produced its own controversies, including a case in which the Jesuit director was condemned to death before being reprieved.

The almanac itself combines several layers: the astronomical calendar, the sexagenary cycle of days and years, the twenty-four solar terms that govern agriculture, and the selection of days suitable or unsuitable for particular undertakings.

It survives as a living publication. Almanacs are printed annually in Hong Kong, Taiwan and among Chinese communities elsewhere, consulted for weddings, funerals, moving house and opening a business, and they remain among the best selling books of their kind.