Origins and History of Chinese Date Selection

Shang beginnings

The roots of the practice reach back to the earliest periods for which written records survive. In the divination of the Shang dynasty, questions inscribed on ox bones and turtle shells often concerned the suitability of particular days for sacrifices, hunts, and military action. Whatever else these inscriptions show, they reveal a settled assumption that days differed in their quality and that the right day mattered. The sixty-day cycle formed from the ten heavenly stems and the twelve earthly branches, already in use to name days in the Shang, provided the framework within which such judgements could be made, and it has remained central to date selection ever since.

The Qin daybooks: the earliest manuals we can read

For the Shang and Zhou periods we have inscriptions rather than instructions, and it is not always clear what rules lay behind a judgement. That changes abruptly with an archaeological discovery of the twentieth century. Tombs of the late Warring States and Qin periods have yielded bundles of bamboo slips containing texts known as Daybooks (日书) — the earliest date-selection manuals that survive in a form we can actually read.

The best known were excavated in 1975 at Shuihudi in Hubei, from the tomb of a minor Qin official buried around 217 BCE. They are working handbooks rather than philosophical treatises. They list days and state what may and may not be done on them: when to marry, when to travel, when to build, when to take up an official post, when to bathe a horse or to sew clothes. They give methods for judging whether a runaway will be recovered and whether a newborn will prosper.

Two things about them are worth holding on to. First, the format has barely changed in twenty-two centuries: a day, a list of activities permitted, a list forbidden. Anyone who can read a modern almanac would recognise the layout at once. Second, they were already the property of a middling government clerk rather than of a court specialist, which tells us that consulting such a book was ordinary practice among literate people well before the empire was unified.

The Han: systematised, and criticised at once

Under the Han the practice was absorbed into the wider apparatus of correlative cosmology. Yin-yang and the five phases supplied a theoretical vocabulary that the Daybooks had largely done without, and the choosing of days became one branch of a general science of resonance between the human and natural orders.

It also attracted criticism immediately, and from inside the tradition rather than outside it. The sceptical philosopher Wang Chong (王充, c. 27–100 CE) devoted several chapters of his Lunheng to the subject. His objections were empirical and are still worth reading. If a day is genuinely inauspicious for burial, why do families who ignore it fare no worse? If a taboo really binds, why does it apply in one region and not the next? If the same day is unlucky for everyone, why do the fortunes of those born on it diverge so completely?

Wang Chong was not an isolated eccentric; comparable objections recur throughout the imperial period, often from officials who used the almanac themselves. The point worth taking is that this was never an unquestioned belief system. The arguments now made against date selection were made, in almost the same terms, within a century or two of its first written manuals — and they did not slow its spread in the slightest.

Competing medieval methods

By the medieval period the choosing of days had accumulated a rich and sometimes contradictory body of method. Different schools favoured different systems: some worked chiefly from the stems and branches and the cycle of days, others from a set of notional stars and spirits thought to govern each day, others from the positions of the real heavens. These approaches did not always agree, and the resulting complexity became a subject of scholarly complaint as well as popular reliance. Attempts were made, especially under later dynasties, to sort and standardise the mass of rules, and imperial compilations were produced to bring order to the field.

Part of that complexity was imported. From the Tang onward, Indian astrological material reached China through Buddhist translation, most influentially in the Xiuyao jing (宿曜经), rendered in the eighth century by Amoghavajra. It brought with it the seven-day planetary week and a body of lore attached to the twenty-eight lunar lodges, which was absorbed into Chinese day-selection and is still visible in almanacs today. Some of what is now presented as immemorial Chinese tradition arrived from India by way of Buddhist monks about twelve hundred years ago, which is a useful corrective to claims of pure and unbroken descent.

The medieval period also saw the rise of a distinct problem that would never be solved: as each school added its own spirits and its own rules, the total body of doctrine grew faster than anyone could reconcile it. Scholars complained about this at the time. The complaint was not that the art was false but that it had become unusable, which is a different objection and in some ways a more damaging one.

The calendar becomes a matter of state

Over the following dynasties the practice grew more systematic. As the calendar itself became a matter of state, tied to the emperor's authority to regulate time, the officials who computed it also concerned themselves with the qualities of days. Bureaus of astronomy and astrology within the imperial government were charged with determining suitable dates for ceremonies, enthronements, and other affairs of court, and the methods they used were gradually written down, debated, and refined. Excavated manuscripts from the early empire, including day-books that list favourable and unfavourable activities for different days, show that ordinary people as well as officials were already consulting such guides more than two thousand years ago.

The Qing compendium

The most important of these efforts came in the eighteenth century, when the Qing court sponsored a great compendium of date-selection method, gathering, sifting, and systematising the traditional rules under imperial authority. Works of this kind gave the practice a measure of official form and helped fix the vocabulary and the categories that later almanacs would use. The state's interest was not merely academic: because the emperor was held responsible for keeping human affairs in step with the order of heaven, the correct choosing of days for great ceremonies was a matter of legitimacy as well as custom.

The compendium in question is the Xieji Bianfang Shu (协纪辨方书), completed in 1741 under the Qianlong emperor. Its preface is unusually candid, and it records a fact that anyone assessing this art should know: the compilation was undertaken because the existing literature was self-contradictory. Different authorities recognised different spirits, assigned them incompatible rules, and produced almanacs in which one and the same day was declared both suitable and forbidden for the same undertaking.

The editors dealt with this by pruning. They discarded spirits they judged spurious, adjudicated between conflicting rules, and issued the result as the standard. The work is a genuine scholarly achievement and remains the single most useful reference on the subject. But the manner of its success is worth noticing. The contradictions were settled by editorial decree, because no observation existed that could have settled them otherwise — and this is the tradition's own account of itself, not an inference by a modern sceptic.

The popular almanac

Alongside this official tradition ran a popular one, and it is the popular tradition that most people encountered. The spread of printing allowed the almanac to become a cheap and widely owned book, carrying the essentials of date selection into ordinary homes. A farmer deciding when to plant, a family fixing a wedding, a merchant opening a shop, all could consult the printed guide without needing a specialist, though specialists remained in demand for weightier choices and for readings tailored to a particular person. In this way date selection came to occupy two levels at once: an elaborate art practised by experts, and a set of everyday rules of thumb available to all.

Continuity into the present

That double character has carried the practice into modern times with remarkable continuity. The almanac is still printed and consulted; weddings, moves, and business openings are still timed with an eye to the chosen day, in mainland China and still more visibly in Chinese communities elsewhere. The reasoning behind the practice belongs to a classical view of time and cosmos that modern knowledge does not support, but as a living custom, and as a window onto how the Chinese have long thought about beginnings, date selection is among the most persistent legacies of traditional Chinese metaphysics.

How reliable is this history?

A word is owed about the evidence itself, because popular accounts of date selection tend to claim more than the record supports.

The archaeology is solid. The Shuihudi slips are dated, excavated in controlled conditions and published; the oracle-bone corpus is large and well studied; the Qing compendium is an official publication whose compilation is documented. On these points the history is as secure as any in Chinese studies.

What is not secure is the line of descent that popular writing draws between them. It is often implied that a single coherent system passed from the Shang to the present, refined but essentially unchanged. The evidence shows something messier: the layers do not always agree with each other, some rules appear suddenly with no antecedent, and others vanish without explanation. The Daybooks contain spirits that later almanacs know nothing about; later almanacs are full of spirits the Daybooks never heard of.

Claims of specific ancient authorship should be treated with particular care. Texts on date selection are routinely attributed to legendary or semi-legendary figures — the Yellow Emperor, Zhuge Liang, and others — and these attributions are conventions of the genre, a way of signalling that a book belongs to a respectable tradition. They are not statements about who wrote it.

Key points

• The wish to begin something at a favourable moment grew into one of China’s most enduring practical arts.

• Shang oracle-bone divination already asked whether particular days were suitable for particular acts.

• As the calendar became a matter of state, timing acquired official importance.

• By the medieval period methods had multiplied and often contradicted one another.

• An eighteenth-century Qing compendium attempted to settle the competing systems officially.

• A popular tradition ran alongside the official one, and it is what most people actually used.

• The almanac is still printed and consulted, giving the practice unusual continuity.

Sources drawn on for this article include: Richard J. Smith, Fortune-tellers and Philosophers: Divination in Traditional Chinese Society and his work on the Chinese almanac; Joseph Needham, Science and Civilisation in China, on the history of the calendar and the astronomical bureau; and the scholarship on excavated day-books of the early empire, which documents the antiquity of choosing days.