Episode 40: Emperor Wu's Woo

March 29, 2024

We learn about the political events and omens that led to the calendar reform of 104 BC.


Good evening, and welcome to the Song of Urania, a podcast about the history of astronomy from antiquity to the present with new episodes every full moon. My name is Joe Antognini.

Well, last month we looked at the famous “guest stars” in Chinese astronomy, along with the place of eclipses and the planets. As with the month before that, I promised at the end that we would wrap up our tour of Chinese astronomy in the following episode by skipping ahead to the 17th century with the arrival of Jesuit astronomers in China. But I am afraid that I have deceived the loyal listeners of this podcast on yet another occasion. The history of Chinese astronomy has turned out to be such a bounty of delights that I simply have to dwell on the topic a little while longer. So the Jesuits will have to wait until another month.

Now, I also mentioned at the end of the last episode that I would talk about the hsiu, or lunar mansions, and unfortunately I lied on that front as well. I wanted to lead into the hsiu rather gradually, and it turned out as I was writing the episode that I led into the hsiu a bit too gradually and never quite got to them by the end. So that, too, will have to wait for the next episode. Instead, we’ll start with some backstory before we get to the hsiu and talk about an event in the history of Chinese astronomy that I mentioned only in passing two episodes back — the calendar reform of 104 BC.

Now, I’ve mentioned in previous episodes the historical importance of setting the calendar in Chinese political society. Setting the calendar was one of the paradigmatic activities of the Emperor — it was simply one of the things that defined him as Emperor — he was the one who regulated time. And the Emperor was the link between Heaven and Earth. The emperor sat at the center of the Earth, right at its pivot point, about which the Heavens turned. When he acted in harmony with Heaven, all was right in the world — the harvests were bountiful, the weather was pleasant, the omens were auspicious, and the calendar marked the time properly. When the Emperor acted rashly, imposed unjust laws, and punished people unfairly, there was disharmony with Heaven, and this manifested itself in famine, plague, storms, ominous omens, and the calendar would drift from the seasons. A court official named Cai Yong, who must have had an uncommon courage, warned the Emperor in 178 AD that his behavior needed to change, writing:

Since Your Majesty ascended the throne, there has been a succession of natural calamities, with several years being marked by solar eclipses and earthquakes…. You should rectify matters concerning your sacred person, giving careful thought to self-restraint — that will save the situation.

Now, for what it is worth, the surrounding context shows that Cai Yong was not exactly criticizing the Emperor’s conduct per se, but rather the conduct of the eunuchs in the court, who were opposed to Cai Yong’s program of restoring the ancient rituals. But nevertheless, his recommendation that the Emperor change his position with respect to the eunuchs only hardened their opposition to him, and he soon found himself in the position of needing to flee the court and spent the next 12 years in a self-imposed exile in the south of the country.

At any rate, I mentioned this two episodes back, but it is worth repeating: the authority of the emperor setting the calendar in Chinese society was analogous to the authority of the emperor to mint coins with his image on it in Western society. And if the calendar drifted, people would notice, and this was a bad signal of the Emperor’s competence. It might be an early sign that the Mandate of Heaven was slipping away from him. The Zuo Zhuan mentions what might happen if the intercalations were done incorrectly:

In the 12th month during winter there were grasshoppers. Jisun asked Confucius about this unseasonable event. Confucius said, ‘I have heard that insects are all in hibernation after Antares has heliacally set. But Antares is still sinking in the west. This is a mistake by those in charge of the calendar.’

So, the calendar was clearly important in Chinese society, more so than in perhaps any other society, which is really saying something. But what precisely did the calendar regulate? Now, as with most other societies the calendar regulated the things that you would expect it to — when to plant, when to harvest, when certain festivals were to be celebrated and so on. But one of the interesting things about the Chinese archaeological record is that we actually have some quite detailed descriptions of what was to happen at various points throughout the year, and one of the surprising things about these descriptions is just how much the activities of the peasants were micromanaged by the calendar. There is a document from 5 AD that was displayed in a public place, visible to all, though presumably it was only meant for the local officials since the peasants could not read. The document was a decree from the Imperial Court reminding the local officials as to how they were to direct the activities of the local population throughout the year.

Some of the directives detailed in this document were meant for the officials alone. One, for instance, tells them to end the year with a set of rituals:

In the last month of winter, command the responsible officials to carry out the great exorcism and the directional sacrifice and make the clay ox to send off the cold wind.

But many of these directives were intended to govern the activities of the people themselves. For instance, it was common for the local officials to press gang the locals into build or repair the town’s infrastructure. But the decree instructs the officials, “In the first month of spring, do not assemble large groups.” So in the first month of spring, these large-scale repairs or construction projects would not be performed, presumably to give the peasants enough time to plant their crops. Another line says “In the third month of spring, do not shoot birds with pellets, spread nets, or use other techniques to capture them.” Later, “In the second month of autumn, exhort the people to plant wheat. Do not permit them to miss the proper season; if they miss the proper season, carry out the punishment without a doubt.” One of the more remarkable directives governs behavior during the equinoxes:

When day and night are equal, then thunder will make its sound and start the lightning. Three days before the thunder, ring the bell to command the people, saying: When there is thunder, do not become pregnant. Those who do not control their comportment will give birth to imperfect children and are sure to suffer calamity.

So the calendar not only regulated when people planted crops and hunted game, but it also instructed them as to when it was permissible or not to have sex.

Another feature of the calendar that governed behavior were the Fan Zhi days. These were days that the calendar spirit “shen sha” was active and were considered to be of ill portent. Consequently, in the early imperial era officials would often take these days off, though this practice seems to have been curtailed by the Emperor Ming in the middle of the first century AD. The author Wang Fu wrote a century later about an occasion on which the Emperor Ming asked his officials why the common people had presented no petitions to him at his usual dawn audience. The officials responded that it was because it was a Fan Zhi day, so the Bureau of Complaints had been closed. The Emperor chastised them and said that the people had abandoned their farm work and traveled from afar to the capital to present their petitions to him. When the officials then arbitrarily stop their work, this amounts to nothing less than stealing a day from the people. He then decreed that the Bureau of Complaints should receive petitions even on Fan Zhi days.

From what we can tell, these structures were not imposed on an entirely unwilling people. During the early Imperial period a new genre of written work appears called the “rishu,” which is generally translated as “daybook.” These daybooks were not used by the high officials of the Imperial Court, but were intended instead for the lower classes. Probably not so low as the peasants since in the early Imperial period they mostly couldn’t read. But the daybooks seem to have been taken up by the next step up: petty officials, merchants, and so forth, who at least had some minimum of education. And it may be that they conveyed the relevant contents of the daybooks to the illiterate peasants as well.

The daybooks were in a sense a kind of almanac. They would specify which days you should or should not do various activities. But a qualitative difference between a western almanac and the Chinese daybook was that a western almanac will simply inform you as to the propitious days to do various things, or conversely unlucky days that you should avoid. But the choice was yours to make. If you wanted to clip your fingernails on an unlucky day, well, it was your funeral. The Chinese daybook, by contrast, was written much more with a prescriptive attitude, from a sense of authority. It simply told you what the correct days to do certain activities would be. And the proscriptions varied based on your profession. If you were a good petty official, you would follow the prescriptions provided by the text. One of the surviving daybooks sets out the specific days that a petty official could carry out his official duties, or when he could invite commoners into his home. But the rules can get quite specific. One rule says that if your home is robbed on a particular day, the thief will have had a moustache and black moles on his face.

These daybooks are also illuminating for another reason. They were discovered relatively late, in the 1970s. Archaeological excavations recovered a few surviving examples of these texts from some tombs. But combing through the extensive official literature from Imperial China, you would really have no idea that these texts were floating around. So an almost complete absence of any mention of these texts in the official literature is indicative of the kind of disconnect between the highest rungs of Chinese society, about which we know quite a lot, and the lowest, about which we know considerably less. As far as we can tell, the rules set forth in the daybooks were not an imperial edict. Who exactly wrote them is unclear, but they seem to have been useful enough, providing structure to people’s lives, that people adopted the daybooks voluntarily.

So, to sum all this up, as I have tried to make clear in the past few episodes, the calendar was a really big deal in ancient China. And it wasn’t simply important for regulating day-to-day life, but it had political implications as well. I mentioned in Episode 38 how after a dynastic upheaval, one of the first things that a new emperor would typically do would be to proclaim a new calendar to assert his authority. And this leads us to the calendar reform of 104 BC. Now, as we talked about in Episode 37, the Imperial Era of Chinese history begins with the establishment of the Qin Dynasty, canonically held to be in 221 BC. The king of the Qin state managed to subdue the other six states, bring an end to the Warring States Period, and establish himself as the emperor of all of China.

Now, we discussed at some length the consequences of this development on intellectual life in China in past episodes. But despite its influence, the Qin Dynasty was really quite short lived. After just 15 years the Qin dynasty had fallen to the new Han dynasty. And these 15 years were not exactly a peaceful time. In addition to a steady drumbeat of rebellions across the empire, there were several assassination attempts on the first emperor of the Qin Dynasty Qin Shi Huang, one of which we discussed in the last episode when we talked about Zhang Liang. Even though none of these attempts succeeded in killing the Emperor, they did succeed in driving him to paranoia, and as he became older he became obsessed with finding the fabled elixir of life that would confer immortality upon him and he went to tremendous lengths to find this potent potable. As we will see shortly, he was not the last Emperor to be beguiled by this mythical potion. One year before he was to die, the heavens sent him an ominous sign. A meteor fell in the lower Yellow River valley and it was inscribed with the words “The First Emperor will die and his land will be divided.” The Qin Emperor assumed, or at least hoped, that some treasonous individual had written these words on the stone, but no one would confess to the deed. Nevertheless, just to be sure, Emperor Qin Shi Huang executed everybody who lived nearby and had the stone destroyed. Soon after this event the Emperor went on a journey to the east in search of the elixir of life, but either the journey was too difficult for his weakened spirit, or perhaps he found some elixir that was made of mercury or some other toxin and it poisoned him. Whatever the details, the first emperor of the Qin dynasty died during this journey.

Now, similar to the empire of Alexander the Great, the Chinese Empire under the Qin Dynasty was essentially just held together by the sheer force of will of a single man, and when he was gone, it immediately began to fragment. There were a few claimants to the throne who jockeyed for power, but none had the competence of Qin Shi Huang, and the many enemies that he had created across the empire exploited this opportunity to rise up and seize power for themselves. This led to a chaotic four year period called the Chu-Han contention, but when the dust had settled in 202 BC, the ruler of the Han state, Liu Bang, found himself on top and established himself as the new emperor of all of China.

Now this was quite unprecedented in Chinese history. The Qin dynasty had been the first true Imperial dynasty in China, so how was Imperial succession from one dynasty to another supposed to work? It seems that Liu Bang was initially somewhat reluctant to claim the imperial throne and preferred to simply rule an independent Han state, but he was persuaded by his court to establish his own dynasty.

But this whole sequence of events was messy and chaotic. The empire as a concept had only been around for about twenty years, and during much of that time it was fending off attacks from all sides. When the new rulers fell into this role they had to frantically build up the machinery of an imperial state. The historian Sima Qian, who is one of the most important sources we have for this time period, wrote:

At that time, the empire had only just been settled, and they were only just about to knit together the foundational structures; when later the High Empress ruled though a woman, there was still no leisure for dealing with matters [like the calendar]. So they continued using the standard conjunction and ritual colors of Qin.

It was also not entirely obvious to the new emperors how much continuity there should be between the old dynasty and the new. Was the role of Emperor to be conceived of as sitting above any petty concepts of clan or dynasty — continuous across the ages? Or should the establishment of a new dynasty be marked decisively as a new era, a clean break from what came before? Given that the Qin Dynasty had been so short lived, the new Han rulers tended to err on the side of conservatism. They were simply the current occupants of the Imperial throne. The earlier emperors had the Mandate of Heaven, and now they had the Mandate of Heaven. They were not exactly claiming to replace the earlier dynasty, so there was continuity with the past.

Now, prior to the establishment of the Qin Dynasty, dynasties in Ancient China had been associated with one of the five elements that I discussed in the last episode, earth, wood, metal, fire, and water. This association shows up, for instance, in the Spring and Autumn Annals. Now, as we learned in the last episode, these five elements were related to each other cyclically: wood depletes the Earth, metal chops wood, fire melts metal, water extinguishes fire, and earth dams up water. In this association with the dynasties, each successive dynasty was associated with the element that would conquer the previous. So the earliest emperor in this cycle, the mythical Yellow Emperor, was associated with Earth, the subsequent Xia Dynasty was associated with Wood, Shang was associated with metal, and Zhou fire. The author of the Spring and Autumn Annals predicted that the following dynasty would be associated with water, writing

What replaces fire must put water in the lead. Moreover Heaven will first make it manifest that the qi of water is in the ascendancy. The qi of water being in the ascendancy, the new dynasty will give precedence to black.

And indeed, in order to assert his authority over China and the establishment of his new Qin Dynasty, Qin Shi Huang adopted the element of water as his Imperial symbol. And as we saw in the last episode, these elements did not just exist all on their own — there was a whole host of other associations that came along with them. So the element water was also associated with the color black, the number six, the direction of north, and the planet Mercury. Consequently the imperial robes during the Qin dynasty were black, and the number six was frequently referenced. Six horses, for instance, would pull the imperial carriage.

So, once the short lived Qin Dynasty fell and Emperor Gaozu of the Han state took his place, he initially adopted the same symbolism of the Qin Dynasty since he was not exactly claiming to be replacing it with a new dynasty. This state of affairs lasted for around forty years or so. After the death of Emperor Gaozu he was nominally succeeded by his son, Emperor Hui, but really it was his mother, the Empress Lu, who ran things. If you recall from the last episode, it’s around this time that Empress Lu had one of the late emperor’s concubines murdered in a spectacularly grisly fashion and the court astronomers falsified the occurrence of a solar eclipse. Emperor Hui died at the age of 22 after devoting his short adulthood to liquor and sex, and his reign was followed by two more short-lived emperors. Emperor Qianshao ascended the throne at the age of 5 and was murdered by the Empress Lu about four years later, and he was followed by Emperor Houshao who ascended the throne at the age of 12. Emperor Houshao managed to outlive his bloodthirsty grandmother, but he was too young to hope to effectively wield power and was soon deposed in a palace coup and the hapless Emperor was executed shortly thereafter.

The man who orchestrated this coup was another son of the first emperor of the Han Dynasty. He took the name Emperor Wen, and despite his underhanded means of ascending to the throne, he was by all accounts a competent ruler and brought a long-awaited period of stability to China. It is said that during his reign the storehouses were so full of grain that some of it rotted away before it could be eaten. Now, as you can imagine, having a succession of child emperors and then having them murdered after a few years was not conducive to getting things done. Well, thirteen years into the reign of Emperor Wen, in 167 BC, things had at long last settled down and the emperor had been faithfully attending to matters of state. It’s at this time that a man named Gongsun Chen came before him with a proposal. Now Gongsun Chen was not a member of the Imperial court, he was, it seems an independent scholar, but nevertheless he made so bold as to advise the emperor that he should adopt the symbolism of a new dynasty rather than continuing with the iconography of the Qin Dynasty. He wrote,

In the beginning Qin obtained the power of water. Now Han has inherited it. Predicting in accordance with the succession of the end and beginning then Han corresponds to the power of Earth. In response to the power of Earth, a yellow dragon will be seen. It would be appropriate to change the standard conjunction and change the ritual color, so as to exalt yellow.

Now you might think that the emperor would have accepted this proposal enthusiastically. But such a thing was seen as a weighty decision, and the Emperor should not make it casually. He ought to have confidence from the signs of heaven that he was meant to do such a thing — otherwise he might provoke heavenly wrath. One of his advisors, Zhang Cang, argued that no such signs had been seen. In Sima Qian’s history, we read:

At that time the Chancellor Zhang Cang excelled in harmonics and astronomical systems, and he held that Han had its origin in the power of Water, and that the Yellow River having overflowed at the Gold Dyke was an omen of that. Beginning the year in the tenth month, with the colors black outside and red within, was in correspondence with the governing power. As for what Gongsun Chen said, it was wrong. So Gongsun Chen was dismissed.

But even if Gongsun Chen’s idea was not immediately taken up, he had planted the seed of change. And soon, the signs began to appear. Two years later, it was reported that a yellow dragon was seen in the northwest of the country, just has Gongsun Chen had predicted. Having been vindicated, Emperor Wen brought Gongsun Chen back, appointed him to his court, bestowing upon him high honors, and made him responsible for planning the transition to the new set of rituals for the newly established dynasty, including the introduction of a new calendar.

As Gongsun Chen underwent the preparations for the dynastic transition, the auspicious signs just kept mounting. A sorcerer named Xinyuan Ping from the state of Zhao showed up at the court and he claimed to be able to discern the spiritual world. He had noticed that there was increasing activity in the world of the spirits and wanted to call attention to this to the Emperor. He predicted that the Emperor would soon be gifted a jade cup with a secret inscription on it. Sure enough, not long after, someone presented the emperor with an inscribed jade cup. Xinyuan Ping also reported that on one day the Sun had passed overhead at noon as usual, then turned back and passed overhead a second time. The Emperor was extremely excited by these signs and he decreed that henceforth the years would be counted not from the date he ascended the throne, but from the date of these auspicious events. But a good thing cannot last forever, and it seems that Xinyuan Ping did not, in fact, possess a connection to the spiritual realm. Upon closer investigation Emperor Wen decided that he was a fraud and had him executed. After this disappointment Emperor Wen lost his enthusiasm for the pomp and circumstance around a dynastic change and an invasion of nomads from the north drew his attention to more earthly matters and he died the following year.

His successor was his son, Emperor Jing, who did not seem to have been as interested in the superstitions that had beguiled his father. Emperor Jing more or less continued his father’s policies and executed them competently, but the idea of a calendar reform stagnated during the 16 years of his reign. In 141 BC Emperor Jing died and he was succeeded by his son, Emperor Wu, who turned out to be one of the longest reigning emperors in all of Chinese history. Like his father, and has grandfather before him, Emperor Wu was also a competent administrator. But unlike his father, and to a greater extent than his grandfather, Emperor Wu was much more spiritual. His father and grandfather had been advised by scholars who had synthesized the legalist tradition favored by the Qi Dynasty with Taoism. The traditional Confucian school had been marginalized during their rule. But Emperor Wu found the Confucian school much more to his taste. He decreed that the legalist school “disturbed the good order of the state,” and ordered a revival of the plans to establish the new dynastic rituals, along with a new calendar.

With the Confucian school ascendant, the formerly powerless Confucian scholars began to press for the emperor to perform the fabled feng and shan rituals. Now just a few words about the feng and shan rituals. These were perhaps the most important and powerful rituals in the Confucian tradition. The feng and shan rituals consisted of two parts: a sacrifice to heaven, and a sacrifice to Earth, and could only be legitimately performed by the Emperor himself. The Emperor would ascend to the highest mountain, typically Mount Tai, and offer a sacrifice to heaven at the summit, and then descend the mountain and offer a sacrifice to Earth at the base. Having done so, the Emperor, in his person, would join together heaven and Earth, and thereby receive the Mandate of Heaven. The precise nature of the sacrifices is not entirely clear. Sima Qian, the great historian of this era, described that the emperor would build an altar out of rock and soil at the summit of the mountain, and would clear a patch of land at the base of the mountain. But the unusual feature of the feng and shan rituals is that they were considered to be so powerful that they were performed exceedingly rarely. In all of Chinese history the feng and shan rituals were only recorded as having been performed on six occasions. It was believed that an emperor could only secure the Mandate of Heaven through these rituals if there had been a long period of peace and stability with numerous good omens. Then, he had to perform the ritual exactly. But the trouble was, because the last time the ritual had been performed was centuries in the past, it was never clear to a sitting emperor who wanted to perform these rites what exactly they were. There was no one alive who had seen it before. He would need to counsel from scholars who poured over the ancient texts for clues, and he would consult diviners who would contact the spiritual world and learn from them what the appropriate rites were. And it goes without saying that he would have to stay apprised of any omens in the heavens, and choose the most auspicious moment to perform these rituals.

So, all this is to say that when the Confucian scholars in Emperor Wu’s court began to lobby for him to perform the feng and shan rites, it was a very big deal and something to take very seriously. Now, in the broader political history of China, Emperor Wu’s reign is characterized by an unprecedented expansion in the size of the Chinese Empire. Prior to his reign, the Chinese Empire more or less spanned the areas around the Yellow and Yangtze rivers. But during his reign the Empire expanded south as far as modern day Vietnam, north to the Korean peninsula, and west as far as Kyrgyzstan. The state became more centralized and professional. But despite these major changes, it was not really the focus of Emperor’s energy. He seems to have appointed competent people to carry out this program, but his own personal focus was on far more spiritual matters. In particular, he wanted to revive the ancient imperial rituals that brought together heaven and earth, most importantly the feng and shan rituals, and as time went on, he also became obsessed with the idea of immortality. For a time he took to drinking a concoction that his doctors called a spiritual dew, which consisted of taking the morning dew and mixing it with finely ground jade. Apparently, though, the spiritual dew eventually made him violently ill and he had to stop drinking it.

Now, at the end of the last episode I talked about the Taoist idea of the “xian,” an immortal spirit. I mentioned that from time to time a xian might visit the Earth, whether as a hermit living in a cave in a remote mountain, as in the case of Huang Shigong, or within the Imperial court, as with Dongfang Shuo. But most of the time, the xians were said to take up residence on Mount Penglai. This Mount Penglai was supposed to be on an island some way out in the Pacific Ocean and was an enchanted land. The palaces were made of gold and silver, jewels grew on trees, there was no suffering, and your rice bowl and wine glass would never empty, no matter how much you ate or drank. But beyond these sensual pleasures, the island was said to be the source of the elixir of life, the mysterious potion which the mother goddess of the west brought to the Imperial court in the last episode, and which was gifted to the archer Hou Yi. This glorious realm was tended by a sorcerer named Master Anqi, himself a xian, who was now more than 1000 years old and who could make himself invisible.

Well, around eight years into Emperor Wu’s reign, a man named Li Shaojun arrived at the court. Li Shaojun claimed that he was hundreds of years old, although he was circumspect about his precise age. During a feast, one of the guests was an official who was over 90 years old. Li Shaojun told the old man that he had known his grandfather well, and that he had practised archery with him at a particular spot. The old man remembered accompanying his grandfather to that very spot when he was a young boy.

Well, among his various exploits that he recounted to the Imperial court, he said that had, in fact, visited Mount Penglai and met Master Anqi. Li Shaojun told the emperor that if he, too, wished to visit Mount Penglai and receive the elixir of life, that could be arranged. He would have to prepare himself by performing a set of rituals to make him worthy to visit the fabled land. He pointed to the example of the legendary Yellow Emperor, who had performed the feng and shan rituals and thereby achieved immortality for himself. This suggestion sparked a fierce debate within the court with two factions. One faction aligned themselves with Li Shaojun and argued that the feng and shan rituals were to be done with the aim of achieving immortality. A more conservative, less superstitious, faction argued that the feng and shan rituals were more to express gratitude to heaven and earth, maintain harmony between the two, and achieve the Mandate of Heaven.

But Emperor Wu was much more interested in one of these interpretations — the one that would give him eternal life. Now, as it happened, the centuries old Li Shaojun died not too long after this. At least that is what the skeptics said. For Emperor Wu this was just further evidence of Li Shaojun’s spiritual credentials. Having completed the task he had set out to do on Earth he had metamorphosed into a xian and slipped off the bonds of the physical world.

But this still left Emperor Wu in a bind. Li Shaojun had been his only contact with Mount Penglai. So the call went out for anyone else who could show the emperor to this storied land. And sure enough, a parade of individuals followed, all of whom claimed various connections to the spiritual world. Coming forward in this way seems to have been a high risk high reward strategy for the purported diviners. Most of them seem to have been executed as frauds. As an example, in 120 BC, one figure, named Shao Weng, managed to summon the spirit of a deceased concubine of the emperor. But whatever he did that was so convincing, he seems to have been unable to repeat the trick and a year passed without an further contact with the spiritual realm. Desperate for something, anything, he seems to have written out a message from a spirit which he then claimed to have discovered. But the emperor noticed the similarity of the handwriting of this spirit’s note with Shao Weng’s own handwriting, and had the hapless diviner executed.

A somewhat more successful diviner, at least for a time, was Luan Da. He arrived at court and claimed to have been an assistant of Li Shaojun. He said that he had accompanied Li Shaojun on his trip to Mount Penglai and had even briefly met Master Anqi. Unfortunately, he said that as he was a mere commoner, he was not permitted to accompany Li Shaojun onto the island, and so he was not privy to any of its secrets. To demonstrate his credentials he produced a kind of chess board with game pieces on it and by chanting he caused the pieces to move of their own accord. Today it’s believed that he probably used a magnetic rock like a lodestone to accomplish this feat. In turn Luan Da expressed some skepticism towards the emperor. He said that he had heard that many of his fellow sorcerers had been executed — how could he be sure that he would not meet the same fate? The emperor reassured Luan Da that these were simply rumors. And what’s more, it seems that Emperor Wu had come to regret these executions — after all, what if they hadn’t been frauds after all, and he had killed the only men who knew the secret of the elixir of life? At any rate, if Luan Da’s main obstacle to finding the elixir of life was that he was a commoner, that was something that was easily fixed. Overnight Luan Da rose from his humble origins to become the second most influential man in the palace. Tantalized by the prospect of at long last obtaining the elixir of life, Emperor Wu gave him not just one, but four of the highest noble titles, married him to his eldest daughter, and gave him an enormous dowry, along with a vast estate and a mansion supported by a thousand servants. Luan Do took with ease to his newfound role as one of the most important men in the Imperial Court. He did so so naturally, in fact, that he more or less never bothered with upholding his end of the bargain and journeying to Mount Penglai. After around a year, the emperor sent a messenger to him and reminded him of his appointed task. He tried to postpone his journey a few times, pleading that he needed more time for preparation, but eventually he realized he needed to go before the Emperor’s patience ran out. So he made a great show of leaving court and traveling east to return to Mount Penglai. For his part, the emperor sent a spy to trail Luan Da and report back as to what he saw. Luan Da and his company travelled to Mount Tai, and there on the mountain he performed a ritual to summon a xian who would provide him directions to Mount Penglai. After the ritual no xians appeared, but this was expected. Luan Da told his assistants that this was because they were commoners. They would need to descend the mountain and he would go forward on his own to meet the immortal. So he went on alone, but unbeknownst to him, was being followed by the Emperor’s spy. The spy saw Luan Da walk around a little bit, but no xians appeared. When Luan Da returned to court he said that he had had great success. A xian had appeared to him and had told him how to find Mount Penglai. But the emperor had already been forewarned by his spy and had Luan Da executed as a fraud.

Well, as Luan Da was preparing for his journey in the summer of 113 BC, another omen appeared. A diviner had been performing a routine ritual at a newish shrine of Hou Tu that the Emperor had erected when he had noticed a glint of metal in the ground. Curious, the diviner dug it out and discovered that it was a strange vessel called a ding. These were a kind of cauldron supported by three legs with two handles and were an important symbol of authority in ancient China. Only the nobility were permitted to use a ding in ritual sacrifices, and the number of dings one was permitted to use was tied to one’s noble rank. A court scholar could use between one and three dings, a minister could use five, and a vassal lord seven. The Emperor alone used nine dings. The nine cauldrons thus became a symbol of imperial authority throughout Chinese history, in the same way as the orb and scepter were in European history. In all probability, this discovery really did happen. The shrine was likely built on the site of a more ancient shrine, and based on the fact that the script on the newly discovered cauldron was unintelligible, it is believed to have been a Shang Era artifact that had been buried there more than a millennium ago and which was eventually exposed through the gradual process of erosion.

Now, despite his seemingly credulous nature, Emperor Wu was initially not sure that this discovery of an Imperial cauldron was a good omen. After all, the Emperor pointed out that there had recently been a string of bad omens: in particular harvest failures and floods. But his officials assured him that this was a good omen, and no small thing. They pointed to past discoveries of a ding, and it was always a sign of heavenly favor for a wise and just ruler.

Well, a few months later, another individual arrived at Court. This was a man named Gongsun Qing, and he was somewhat cannier than the earlier diviners. He never claimed to be able to contact the spirits himself, he simply had a number of acquaintances who were able to do this and he never hesitated to pass along their stories to the Emperor. He said that he had been in contact with a well known diviner named Shen Gong, who had, in turn, spoken to Master Anqi at Mount Penglai. Unfortunately Shen Gong had died, but he had left his writings to Gongsun Qing, and many of these emphasized the importance of the Imperial cauldrons. Gongsun Qing also seems to have had some training in astronomy and used it to bolster his case. Gongsun Qing’s thesis was that there were substantial parallels between the reign of the great Yellow Emperor and the events of the present day. The Yellow Emperor, too, had discovered a regal cauldron during his reign. What is more, that year, the winter solstice fell on the first day of the month and the 46th day of the sexagenary cycle, the cycle of 60 days that I discussed in the last episode. From the histories, Gongsun Qing noted that 380 years later, the Yellow Emperor had then performed a special rite at Tripod Lake, during which he cast a new bronze cauldron using ore from Mount Jing, and thereupon a great dragon bore up the Yellow Emperor to heaven, along with seventy lucky officials. Gongsun Qing calculated that the year that happened, the winter solstice fell on the first day of the month and it was also the first day of the sexagenary cycle. In Gongsun Qing’s interpretation, this was clearly the most auspicious moment, the time that the Emperor would achieve immortality. This event, the correspondence between the winter solstice, the first day of the 11th month, and the first day of the sexagenary cycle was nothing less than the start of a new era, and this happened only every 4617 years. Now, the Yellow Emperor had had 380 years to prepare since the discovery of his cauldron before this auspicious time and the attainment of immortality. But Emperor Wu had much less warning. These events happened in 113 BC, and the next time this conjunction would occur, was in 105 BC, so there were only eight years to prepare. Gongsun Qing informed the Emperor that the preparations would not be easy. According to Shen Gong’s writings, seventy-two past Emperors had attempted to perform the feng and shan rites, but only the Yellow Emperor had succeeded in attaining immortality. It was of the utmost importance that he prepare diligently. That year, Emperor Wu finally acquiesced to the proposal that one faction of his had been lobbying for, to perform a sacrifice to the Tai Yi, the Grand Unity, who was seen as the supreme deity during the Han Dynasty. He prayed:

Heaven began by granting the precious cauldron and the numinous reckoning to me, the Sovereign Emperor; now after new moon succeeding upon new moon the cycle has reached its end and will begin again. Now as Sovereign Emperor, I reverently perform obeisance.

He then spent the next several years with his singular focus being preparation for the feng and shan rites. Incidentally, during his preparations he was performing a sacrifice at the tomb of the Yellow Emperor when he had a realization. The Yellow Emperor had supposedly been borne off to heaven, and yet here he was at his tomb. But his officials reassured him that the tomb did not contain the Yellow Emperor’s body, of course, he had indeed ascended into heaven. But his robe and hat had fallen off in the ascent, and they had been buried here. This answer seemed to satisfy Emperor Wu.

By the year 110 BC, Emperor Wu felt that he had at long last done everything necessary to perform the feng and shan rites, the key step to summon the immortals and achieve immortality. He traveled to Mount Tai in yellow robes representing the new Han dynasty, and at its base he built an altar out of the Earth that was nine feet tall and twelve feet long. Below it he buried jade tablets on which were written a secret prayer. He then ascended to the summit with an assistant and there he performed the secret fang rite to the Heavens. After spending a night on the mountain, he descended in the morning and conducted the shan rite to the Earth. Emperor Wu was optimistic that the rites had gone well, and indeed, a few months later, two comets appeared in the sky, which was interpreted as an extremely auspicious omen. All that remained now, was for the Emperor to wait five years until that great moment when the new era began, in December of 105 BC when the winter solstice fell on the first day of the month and the first day of the sexagenary cycle.

Well, at this point in the story the historian we are learning all of this from, Sima Qian, ceases to be a passive chronicler of events that came before him, and begins to play an active role in our story. Sima Qian’s father, named Sima Tan, had held the position of Taishi, which can be translated as Court Astronomer, but also encompassed other clerical duties, along with maintaining the historical record, so the title has been alternatively translated as the Grand Clerk, or Court Scribe, or Court Historian. Regardless, the position was a high one in the court, and among his duties, Sima Tan was responsible for observing, interpreting, and predicting the activities of the heavens. Sima Tan had been firmly in the Confucian camp that was lobbying for the Emperor to pay reverence to the Tai Yi and to perform the feng and shan rites. Unfortunately he was also of ill health and died in the year 110 BC, before he was able to see this program carried out by the Emperor. But prior to his death he encouraged his son to follow in his footsteps. As I mentioned back in Episode 38, in the early Imperial Era, and before, these high offices were hereditary positions, so Sima Tan’s son, Sima Qian, inherited the role. In Confucian tradition, a son had to spend three years in mourning after the death of a parent, so Sima Qian did not take up his duties until 108 BC. Now that the Emperor had performed the great feng and shan rituals and the arrival of the new era was imminent, the court astronomers, with Sima Qian among them, had to develop the new calendar for this era within the next three years.

Now, one of the unusual things about Sima Qian’s narrative here is that despite the fact that as the Court Astronomer, he clearly must have played an integral role in the development of this new calendar, he barely touches on it in his history, and at no point does he mention his own involvement. To understand what happened during this calendar reform, and to understand why Sima Qian was so taciturn on the topic, we have to turn to a work written by the historian Ban Gu more than a century later, called the Han Shu, or Book of Han. Ban Gu informs that, indeed, as we would expect, Sima Qian was intimately involved in the calendar reform, and not only that, had been a strong proponent of the idea that the calendar should be reformed. The emperor then gave Sima Qian, along with Gongsun Qing and others the go-ahead to begin to compute the new calendar. Ban Gu writes

Then an edict was issued to Gongsun Qing, Hu Sui, Sima Qian and the Attendant Gentleman Zun, the Senior Star Observer She Xing and others, that they should consult on the construction of a Han astronomical system. So they fixed east and west, set up gnomons and set water clocks running, in order to find the extents of the 28 lunar mansions in the four quarters, and to seek a conclusion of cycles so as to fix the first and last days of months, with the equinoxes and solstices and to trace the orbits of crescents and full moons.

But then an interesting detail follows.

But She Xing and his colleagues submitted a memorandum saying that they had been unable to perform the calculations, and they wished to recruit specialists in astronomical systems so as to make the measurements more accurate, with each proposing their own additions and subtractions, in order to make a [new calendar for the Han dynasty].

Later on, Ban Gu describes how these external specialists devised 18 different calendar systems, but that Sima Qian was ordered to use the one devised by an astronomer named Deng Ping. Now this is an odd thing. Sima Qian was the Court Astronomer — there really wasn’t anyone higher than him in the org chart apart from the emperor. Why was he being ordered to use this outsider’s system? Evidently he and the other big shots in the court were unable to get the numbers to work out and some contractors had to be brought in to sort out the mess, probably with the emperor’s knowledge at a minimum, and maybe at his behest. In this light, Sima Qian’s brevity on this episode in his career is maybe more understandable.

So what was the issue in this calendar reform that everyone was having so much trouble with? Well, if we go back to the reason that the calendar reform was being proposed, in the year 105 BC, the winter solstice would coincide with the first day of the month and the first day of the sexagenary cycle, and when this had last happened, the Yellow Emperor and much of his Court had ascended into heaven and become immortals. Now, if you recall, the first day of the month was not an arbitrary date as it is in our modern calendar. The first day of the month was the new moon. The problem that everyone was dealing with, is that with modern techniques, we now know that in this year the winter solstice fell on December twenty-third at 7:35 PM in the capital, whereas the new moon occurred on December twenty-fourth at 7:10 AM. The first day of the sexagenary cycle was on December twenty-fifth. So what probably happened is that proponents of the calendar reform had used some approximate, out of date techniques to figure out when the winter solstice and new moon would occur, and, to their delight had discovered that they would coincide with the first day of the sexagenary cycle in 105 BC. But then they went and started to perform more detailed observations to really nail down when the solstice and when the new moon were, and to their dismay, found that it was not falling on the day that it was supposed to. This great conjunction, which was to mark the start of a new era and bear the Emperor off into immortality, wasn’t going to happen. This was inconvenient. And actually, knowing the track record of astronomical observations in the early Imperial period, this was not much of a surprise. As I mentioned in the last episode, the astronomers were somewhat faithful recorders of lunar and solar eclipses. But weirdly, solar eclipses were not generally recorded as happening on the first day of the month, which they should. A solar eclipse can only happen at the very moment of a new moon, and this was by definition the first day of the month. But typically solar eclipses were recorded as happening on the last day of the month, or even the day before that. It seems that what had happened in the early Imperial period was that the astronomers had been calculating their calendar with a lunar period that was somewhat too long and had gone a long time without calibrating it. Over the centuries, this error had built up, and by now the calendar was running about a day ahead of where it was supposed to. Now, to modern astronomers, seeing a solar eclipse on any day other than a new moon is a clear indication that you’ve calculated the day of the new moon wrong. But it does not appear that anyone in the early Imperial Era noticed that this was a problem. So this error in the calculation of the date of the new moon lurked beneath the surface until it became a big honking problem during the calendar reform of 104 BC.

Now, fortunately, the techniques available to astronomers of the time made this a surmountable obstacle. In the end, Deng Ping was in the end able to square this circle. The fact of the matter was that it was difficult to measure the winter solstice very accurately. They were using a gnomon and measuring the length of a shadow at noon near the winter solstice to determine its date, and because the Sun’s elevation doesn’t change very much around this time, it’s hard to measure the date to better than a few days. And likewise it is difficult to determine the time of a new moon, particularly if you are not taking advantage of solar eclipse observations. So there was a lot of wiggle room. It seems that Deng Ping tweaked the length of the month and the year to be a little longer than it had been in previous system. The month was 1.1 seconds longer and the year was 14 seconds longer. And by using a reference point far enough in the past he was able to nudge the expected date of the solstice and new moon in 105 BC to be December 25, the first day of the sexagenary cycle. And so Deng Ping saved the day, quite literally, and Emperor Wu would be able to go to heaven after all.

Well, as a postscript to the events that led up to the calendar reform of 104 BC, Emperor Wu did not end up ascending into heaven as he had hoped when the grand conjunction arrived. Nevertheless, ever the true believer, he did not lose hope and continued to pursue the secret of immortality right up until he died in 87 BC. Sima Qian died just one year later, but the last two decades of his life were somewhat more difficult. In 99 BC, Sima Qian became caught up in some palace intrigue called the Li Ling affair. Without going into too many details, Li Ling was a general who was blamed for a disastrous defeat in the north. Although he was not close to Li Ling, Sima Qing respected him and seems to have said some words in his defense at court. But the other general who was involved in this defeat was Li Guangli, who was the brother-in-law of the emperor, and the emperor interpreted Sima Qian’s defense of Li Ling as casting blame on his brother-in-law — and on himself by extension. As punishment, he was given the choice between execution and castration. Now, ordinarily a man of his rank would have rather committed suicide than undergo the humiliation of castration. But Sima Qian, the consummate scholar, chose castration so that he could finish his books, despite describing it as “the worst of all punishments.” For this, those of us interested in the history of astronomy, and the history of China more generally, are eternally grateful.

Well, I had hoped to talk in more detail about the lunar mansions in this episode, but I am afraid it will have to wait until next month. Then, I promise, we will at long last learn about the system of lunar mansions, as well as a few of the greatest astronomers in Chinese history: Zhang Heng, and Shen Kuo. I hope you’ll join me then. Until the next full moon, good night and clear skies.

Additional references

  • Cullen, Christopher, Heavenly Numbers
  • Needham, Science and Civilisation in China, Vol. 3