Demons, Contagion, and Epidemics

The therapeutic principle of utilizing poisons is already visible in The Divine Farmer’s Classic. In the preface, the Han text recommends the use of different types of drugs to treat different categories of disorders. A warming drug, for example, should be harnessed to counter cold maladies, and vice versa. To treat indigestion, one should take drugs that induce vomiting and draining. Importantly, the text singles out potent drugs to combat two specific conditions: demonic infestation and gu poisoning.² What were these disorders? And how do we make sense of the logic of treating them with poisons?

Let’s start with demonic infestation (guizhu). It is a conspicuous class of illness in The Divine Farmer’s Classic—more than twenty drugs in the text are recommended to treat the malady. The compound components of the word itself merit explanation. The first component, gui, is a multivalent word that in early Chinese sources generally referred to various kinds of spirits, either benevolent or nefarious. Gui could refer to the spirit of a dead person, similar to the concept of a ghost, or to a deity offering blessing or protection. It could also designate the spirit of an animal (dog, snake, fox, etc.) or an inanimate thing (mountain, river, tree, etc.).³ In medical texts, however, the word almost always carries a negative sense, referring to either the disquieted spirit of the deceased haunting the living or demonic entities of diverse origin that assault the body. Gui, in short, were believed to be malevolent forces that could trigger devastating illnesses.

If gui reveals the cause of sickness, the second component, zhu, depicts its dynamics. According to a first-century dictionary, zhu means “pouring.”⁴ Building on this basic sense, a third-century lexicon interprets zhu as a condition wherein “when one person dies, another person contracts the illness as the result of qi pouring in.”⁵ This implies that the illness is contagious. Yet unlike the modern conception of contagion, it is only after the afflicted person dies that the illness can be transmitted to others, indicating that the dead body is the source of the pollution.⁶ To explain the mechanism, qi is the key: a deceased body emanates poisonous qi, which pours into a healthy body, leading to its collapse.

Upon investigating its individual components, the meaning of guizhu becomes clear: it refers to a set of contagious disorders that are induced by demonic agents. The symptoms of guizhu are varied and serious. According to Formulas for Emergencies to Keep at Hand (Zhouhou beiji fang), a fourth-century medical work by Ge Hong, demonic infestation expresses itself in sundry symptoms, ranging from thirty-six to ninety-nine different types. The common patterns include alternating chills and fever, dribbling urination, a state of confusion and quietness, not knowing the origin of one’s suffering, and pains all over the body. Over time, the patient loses vitality and eventually dies. The illness then spreads to people nearby, sometimes leading to the annihilation of an entire family. When encountering such symptoms, Ge urges, one must take prompt action. Demonic infestation, in brief, signifies a critical situation that demands swift treatment.⁷

Where did the etiology of guizhu come from? The notion of illness caused by demonic attack has ancient roots. In the pre-Han era, demons were often held responsible for conditions that were acute, that seemed to occur by chance, and that seemed detached from human culpability. Sometimes, these disorders exhibited contagious symptoms, though the idea of “infestation” (zhu) had not arisen.⁸ The situation changed in the Eastern Han dynasty (25–220), when demonic maladies became associated with dead bodies that were dangerously contagious. In particular, a new type of funerary writing emerged in the Han tombs that displayed overt concerns about contagion. Called “grave-quelling writs” (zhenmu wen), these injunctions aimed to suppress the miasmic influence of a corpse with the help of heavenly deities so as to protect the family of the deceased. Revealingly, the advent of such writings coincided with the occurrence of a series of epidemics in the second and early third centuries that ravaged the country, leading to the development of funeral rituals, possibly mediated by shamans and certain fangshi, to manage these devastating events.⁹

With the rise of Daoism at the end of the Han period, the conception of demonic illness changed again. The early Daoist movement known as the Way of the Celestial Masters (Tianshi Dao) that developed in the southwest in the second century used healing as an effective way to recruit followers. In their etiological framework, demons were taken to be the cause of many types of illness.¹⁰ In contrast with earlier views, Daoist practitioners often imagined demonic attack as the unfortunate outcome of the moral failing of the individual. The Celestial Masters, for example, created a ritual space called “the quiet chamber” (jingshi) in which patients were to confess their sins and repent before petitions could be sent out to the gods requesting a cure.¹¹ Illness could also be hereditary: the faults of one’s ancestors could affect the body of a descendant, making it susceptible to disasters. In another scenario, the spirits of the dead could file “sepulchral plaints” (zhongsong) to the court of the underworld to claim justice, which often entailed punishing the living descendants of the accused with sickness.¹² Therefore, illness in Daoist terms was not just a physiological concept but one entwined with the moral conduct of the individual and its repercussions across generations.

Later Daoist movements followed suit and began blaming demons for epidemics. A Daoist treatise of the fifth century depicts an apocalyptic scene in vivid detail.¹³ In an age of moral chaos, swarms of demons plague the human world with myriad illnesses. The Demons of Great Thunder, leading their eighty thousand underlings, spread thirty-six kinds of malady; the innumerable Demons of Youjian are responsible for the sickness of red-swelling; the Demons of Red Eyes induce vomiting and dysentery upon invading the bodies of victims.¹⁴ There is even a kind of demon called “attached offspring” (fuzi), which is nine feet tall, with three faces and one eye. The name coincides with that of the potent herb aconite (discussed in chapter 2), revealing the close relationship between powerful drugs and demonic illness.¹⁵ The text conspicuously identifies the names of many demons, as the calling of names was considered an effective way to target and destroy vicious beings in early Daoist rituals. In fact, the entire scripture is devoted to using incantations, often including the invocation of specific names, to annihilate demons.

Medical works from the fifth century on shared the demonic etiology as seen in Daoist healing practices, but with a shifted focus that tied demonic attack to the condition of the body.¹⁶ The issue is elaborated in On the Origins and Symptoms, which is the first book devoted to etiology in Chinese history. The text emerged during the Sui dynasty (581–618), the period that marked the end of a three-century-long political division between the northern and southern dynasties. In this new political climate, the court set up medical institutions and sponsored several medical works that paved the way for the governmental regulation of medicine in the centuries to come.

One of these court-commissioned projects was On the Origins and Symptoms, produced under the direction of Chao Yuanfang. We know little about Chao, except that he was a head officer in the Imperial Medical Office, a new institution established during the Sui dynasty that aimed to train specialists who would provide medical services for court officials. There were three departments in the office: medicine, therapeutic exercise, and incantation. Although direct evidence is lacking, it is possible that Chao served in the department of therapeutic exercise (anmo) given the extensive discussion of the techniques in his work.¹⁷

On the Origins and Symptoms contains fifty scrolls and sixty-seven categories of illness. For each category, Chao starts with a general discussion of the origin of the illness and its symptoms. This is followed by a series of subsections in which he explains a variety of subtypes of the illness and their respective symptoms. Altogether, he identifies 1,739 symptoms, offering one of the most extensive accounts of etiology and symptomology in premodern China. The work also recommends remedies for chronic and noncontagious illnesses, chiefly in the form of “guiding and pulling” (daoyin), a set of bodily techniques that include stretching, breathing, clacking the teeth, swallowing saliva, and meditation.¹⁸ Drug therapy, by contrast, rarely appears in the book. This is partly due to the immense popularity of daoyin at the Sui court, espoused by an avid emperor who promoted it to an unprecedented degree.¹⁹

How does Chao explain demonic infestation? The condition appears in the category of the illness of infestation, which contains thirty-three subtypes, each with distinct symptoms. In the subtype of demonic infestation, Chao states:

The reason that infestation means “to reside” is that the illness lingers, stagnates, halts, and resides [in the body]. There are people who initially have no other illness and are suddenly struck by a demon. At that moment, they sometimes feel piercing pains in the heart and the abdomen; sometimes they feel oppressed in the extreme, falling to the ground, resembling the “malignant stroke” type of illness. After one recovers, the residual qi does not rest. It halts and resides for a long time, and sometimes agitates and moves. It lingers, stagnates, halts, and resides, eventually leading to death. Upon death, it pours into people nearby. Therefore, it is called demonic infestation.²⁰

Two different meanings of zhu stand out in this passage. The first is infestation, which echoes the interpretation of the word in the third-century dictionary examined earlier. A second meaning appears for the first time in Chao’s text, that is, taking up residence inside the body, indicating that the illness is latent, ever ready to plague the victim again.²¹ If the initial attack by demons manifests the sudden and violent aspect of the illness, the lingering qi of these vicious entities left in the body poses an ever-present menace to life. In Chao’s eyes, demonic infestation is an obstinate condition; early therapeutic success cannot guarantee its thorough eradication.

The symptoms of demonic infestation resemble those of “malignant stroke” (zhong’e), a condition in which one is suddenly struck by the qi of a demon, which happens when the guarding spirit of the victim is weak. Malignant stroke is an acute condition: the patient falls sick abruptly, with severe symptoms of piercing pain in the heart and the abdomen, and deadly oppression. If the patient survives the initial assault, the residual qi of the demon may linger in the body and become the illness of infestation.²² Although demonic infestation and malignant stroke are similar and related disorders, there is one subtle but important difference: while demons are blamed for the former, the latter is caused by demonic qi. In fact, the discourse on qi constitutes the most salient feature of Chao’s etiological reasoning, yet this qi-centered explanation of illness was not invented by the Sui physician—it was already abundantly discussed in the Han medical treatise The Yellow Emperor’s Inner Classic.²³ What is new in Chao’s work is his effort to subsume demonic etiology into this ancient conceptual framework, thereby connecting external insults to the condition of the body. He expresses particular concern about bodies depleted of vitality, which are susceptible to demonic attacks and ensuing total collapse. Departing from the explanations of sickness as a moral failing often seen in early Daoist writings, Chao ascribes the rise of maladies directly to the vulnerability of the body.

Overall, the perception of demonic disorders underwent several transformations in Chao’s treatise: a shift in etiological focus from demons to demonic qi, the sensitivity of vulnerable bodies, and the tenacity of the illness. The symptoms were acute and severe, often leading to death and causing contagion. How did Chao treat these intractable disorders? Curiously, he offered no remedies. This is likely because he considered therapeutic exercise, the major method of healing in his work, to be particularly effective to treat mild, chronic, and noncontagious illnesses. For acute and life-threatening conditions, however, he may have deemed the method limited.²⁴

Other seventh-century physicians, such as Sun Simiao, did propose cures to combat demonic illnesses, primarily through drug remedies. In his Essential Formulas, Sun compiled a section with forty-five formulas to treat various types of demonic disorder.²⁵ These formulas differ considerably in the number of ingredients, ranging from single-drug therapies to compound formulas that contain up to fifty ingredients. A common feature they all share is the regular use of potent drugs. One formula called the Great One’s Powder for Emergencies (Taiyi Beiji San), for example, contains nine ingredients, eight of which are potent.²⁶ As the name implies, the formula is used to treat acute conditions induced by demonic attack. Having ingested the medicine, Sun notes, the patient will have a nosebleed if the illness is located in the head, vomit if it is above the diaphragm, go through draining if it is below the diaphragm, and sweat if it is in the limbs. These therapeutic effects indicate that the medicine powerfully purges the body, expelling poisons in the form of blood, sweat, and bodily waste. In other cases, these toxic matters assume more concrete forms. A large, forty-five-ingredient formula named Powder of Golden Teeth (Jinya San) promises that once the patient takes the potent medicine, worms will be discharged with urine and excrement. Powerful drugs were deployed to drive sinister creatures out of the body.²⁷

Finally, there was a strong connection made between demonic infestation and epidemics—contagious illness could inflict large populations with devastating consequences. Epidemics, in fact, constituted a major type of sickness in imperial China, with a history that can be traced back to antiquity.²⁸ Especially during the tumultuous time of the third century, the collapse of the Han dynasty brought wars, famines, and waves of devastating plagues that decimated the population. The rise of the Daoist movement during this period had much to do with its emphasis on ritual healing that offered attractive antidotes to the gloomy reality.²⁹ Drug remedies were also utilized to combat epidemics. One story preserved in Sun Simiao’s Essential Formulas recounts how in 169, an epidemic broke out in Nanyang (in present-day Henan), leading to countless deaths. Witnessing the tragedy, a scholar from Shu offered a pill to the afflicted people, which powerfully expelled demons that caused the suffering. The pill, as revealed by Sun, contained several potent mineral and herbal ingredients. It could not only cure the unfortunate victims who ingested it but also protect anyone from demonic assault who was in a house where the pill had been burned. Potent medicines were mighty weapons to dispel virulent entities.³⁰

The sixth century is another moment in Chinese history when epidemics wreaked havoc. Besides the constant wars between the northern and southern powers, another factor that might have contributed to the surge of illnesses was the sudden climate change in the early part of the century, creating a spell of extremely cold weather that ruined crops and caused large-scale famines.³¹ Small wonder that during this period, demons proliferated in Daoist writings, which often depicted an apocalyptic scene of the descent of swarms of malign forces spreading illnesses and exterminating large populations. Devotional practices, such as the recitation of scriptures and the invocation of spells, these texts urged, were the only way to obtain salvation.³² Some of these methods were integrated into the state healing repertoire. Among the three departments established in the Imperial Medical Office of the Sui dynasty, for instance, one relied on incantatory healing, which borrowed both Daoist and Buddhist ritual techniques to fight epidemics.³³ The effort is also seen in the state-sponsored On the Origins and Symptoms, which offered substantial discussion of a variety of contagious disorders.³⁴ The institutional responses to epidemics, together with the elaborate conceptualization of such illnesses in medical writings, provided both theoretical reasoning and a practical guide for combatting contagion, which would have repercussions for centuries to come.³⁵

Gu Poison

The other type of illness that potent medicines targeted, encapsulated in The Divine Farmer’s Classic, was gu poison. The meaning of gu was complex and changed over time. Its graph, which appeared in oracle bones (second millennium BCE), depicts one or two wormlike creatures sitting in a vessel. It refers to a pathological condition often located at a specific site in the body (bones, teeth, etc.). These early pictographs already imply a connection between gu and poison: placing vermin inside a vessel, which may also designate a container for food, could cause serious harm.³⁶

Later sources in antiquity further elucidate the meaning of gu. In Zuo Commentary (Zuozhuan, ca. fourth century BCE), a work that chronicles the major political events in the ancient state of Lu, we encounter the revealing story of a duke from the state of Jin who summoned a physician to treat his sickness. The physician, named He, claimed that the duke was incurable because he had contracted a gu-like illness resulting from sexual indulgence. Later, when a minister approached He and asked him the meaning of gu, the physician explained that it was “what excess, indulgence, delusion, and chaos generate.” He also considered gu to be the way that grains could change into flying vermin. Moreover, he cited The Classic of Changes to interpret the word as “women deluding men or the wind blowing down [the trees] in the mountain.” Pleased with He’s answer, the minister sent him off with lavish gifts.³⁷

Above all, He correlated gu with the seductive power of women. The perceptive physician believed that gu was induced by intemperance, which spoke to the duke’s reproachable and life-limiting sexual indulgence. Earlier in the conversation, he offered a lengthy explanation of this disorder in the framework of “six qi” that tied excessive behaviors to the malfunctioning of the body. The sickness of delusion (huo), he reasoned, derived from the excess of obscurity, which implied the hours of darkness when intercourse occurs. The sexual excess then generated heat inside the body and turned into gu illness.³⁸ To further support the female connection to gu, the physician presented evidence from The Classic of Changes in which sixty-four hexagrams were used to make predictions. The hexagram for gu is ; it consists of the upper trigram , which means “firm” or “mountain,” and the lower trigram , which means “supple” or “wind.”³⁹ He thus interpreted the combination as women (a supple force) deluding men (firm beings), or the wind blowing down trees in the mountain, the latter signifying a destructive female power bending and ruining what stands upright, namely, male authority.⁴⁰ In addition, the physician also explained gu as grains transforming into flying vermin. This possibly refers to the emergence of insects from grains as facilitated by wind, given the close connection between wind and worms in ancient China.⁴¹ More obvious is the idea of transformation associated with gu—its potential to morph into myriad things that are hard to predict and elusive to capture. This concept of gu became linked to demons in later sources.

Among the diverse meanings of gu, the connection to what was referred to as chong was the most prominent and enduring. Chong, often translated into English as “worm,” is impossible to correlate to a single biological entity. The Han dictionary Explaining Characters simply defines it as “creatures with feet” and relatedly defines gu as “chong striking the abdomen,” indicating an animal insult on the body.⁴² In various contexts, chong could refer to animals in general or small, crawling creatures such as reptiles, insects, and worms.⁴³ As far as gu is concerned, it usually designates destructive and sinister agents that either assault the body from the outside or impair it from within. The association of gu with animals, large and small, became more conspicuous during the Era of Division. In Records of Searching for the Spirits (Soushen ji, fourth century), for example, gu was depicted as a demonic agent that could morph into diverse animal forms such as dogs, boars, worms, and snakes. These dangerous creatures would then slyly approach human beings, strike, and kill.⁴⁴ In other cases, gu referred to malicious human manipulation of vermin. A story in The Sequel to Records of Searching for the Spirits (Soushen houji, fifth or sixth century) describes a southeastern family who bred gu. Guests who ate their food would spit blood and die. But, the text recounts, when a monk showed up and was offered the poisoned meal, he chanted a spell, which caused two large centipedes to crawl out of the plate. The monk then safely ate his meal uninjured.⁴⁵ Gu poison here involved the manipulation of dangerous insects to corrupt food. Correspondingly, the removal of them, in this case by a ritual action, neutralized the curse.

The menace of gu also drew the attention of medical writers.⁴⁶ In his On the Origins and Symptoms, Chao Yuanfang dedicates a scroll to the discussion of various illnesses caused by gu. It is one of the most elaborate accounts on the deadly poison in medieval China. Chao defines gu as follows:

There are many types of gu poison, all of which are qi of change and delusion. There are people who deliberately manufacture gu. They often catch creatures like worms and snakes, use a vessel to store them, and leave them to freely devour each other. The only thing that remains [in the vessel] is called gu. It then can change, and become the source of delusion. Eaten following alcohol and food, it afflicts people with disaster. The affliction of others [in turn] brings fortune to the owner of gu. Therefore, untrammeled outlaws store and worship gu. There is also flying gu, which comes and goes without reason, with the hidden state like demonic qi. People who are afflicted by it suddenly contract severe illnesses. Those who are hit by gu-induced illnesses often die. Because of its great power of poisoning and harming, it is called gu poison.⁴⁷

Chao’s formulation clearly links gu poison to vermin, but it is not the direct contact of the poisonous creature with the victim’s body that causes harm. Instead, illness, misfortune, or death result from the malignant qi it emanates, which underscores the elusive and capricious nature of gu poison: it can act from a distance, change constantly, and afflict people “without reason.” In particular, Chao identifies two basic characteristics of gu. The first is its power to change (bian). This quality is already visible in some early accounts of gu, where it is imagined to assume various animal forms. What is different in Chao’s description is his use of amorphous qi to replace concrete creatures, a move consistent with the centrality of qi as an explanatory framework in his writings. The second is gu’s power to delude (huo). This sense of gu is linked to the seductive danger of women in ancient texts, as discussed before. The association of gu with women is not explicit in Chao’s account, but what is clear there is that gu develops out of the destructive intention of its creators. Because there was always a vicious mind behind each gu poisoning, the cure not only concerned the healing of the individual body but also the restoration of social order by eliminating the gu poisoners.

According to Chao, illnesses caused by gu poison were chiefly of two types, both of which could cause severe symptoms. The first type was chronic, likely the outcome of the deliberate manipulation of gu vermin. Chao depicts four kinds of gu poison in this category: the gu of snakes, the gu of lizards, the gu of toads, and the gu of dung beetles.⁴⁸ The maladies caused by this variety of gu often lasted for years, and if left untreated would lead to the death of the patient. Tellingly, each of the four kinds of gu poison acquired its name from a particular type of vermin. Oftentimes, Chao used these names to delineate the morphology of pathological formations inside the body, which could vigorously devour the viscera. For instance, those who were struck by the gu of a dung beetle might spit out something resembling the crawling insect. Since gu preparation involved poisonous vermin, they naturally became the source of pathological imagination.

The second type was “flying gu,” which wandered in nature unattached to a gu manipulator. The illnesses it induced were often acute and life-threatening, leading to the rapid collapse of the body. A seventh-century source describes a flying gu, invisible but emitting the sound of a bird chirping. If someone was struck by it, they would suffer bloody diarrhea and die within ten days.⁴⁹ The acute nature of the condition was obvious. Despite their varied symptoms, both types of gu illness were caused by dangerous vermin, which either crushed a victim all of a sudden or slowly ravaged the vital organs of the body.

How could gu poisoning be treated? In his Essential Formulas, Sun Simiao offered twenty remedies, most of which prescribed potent substances to eliminate vicious vermin. The drugs overlapped substantially with those for expelling demons, such as realgar, croton, aconite, and centipede. Once these powerful medicines were ingested, Sun observed, the patient’s body would experience a violent process of purging, leading to the discharge in the form of worms, snakes, and insects. The efficacy of these formulas was thus found in their power to expunge poisons from the body.⁵⁰

There were simpler remedies too. In order to treat two specific types of gu, cat-demon gu and wild-path gu, Sun recommended incinerating a red snake that had happened to die on the fifth day of the fifth month, and eating the ashes with water collected in the morning.⁵¹ The date specified in the remedy is significant, as it was considered a time of extreme yang, when the strength of a poison reached its apex. The vermillion color of the snake also signifies the fiery power of yang. A snake collected on this day, presumably possessing the highest level of poison, could be turned into a potent medicine to counter the similarly poisonous vermin inside the body.⁵²

This logic of healing, based on the principle of similarity, was also described in the materia medica literature. A telling example comes from the eighth-century Supplement to Materia Medica (Bencao shiyi) compiled by the Tang scholar Chen Cangqi.⁵³ Among the more than seven hundred drugs in this treatise, one is called “gu vermin” (guchong), which can be used to treat gu poison. Specifically, one collects gu vermin expelled out of the body of a victim, dries them, and burns them into black aches. Ingesting these ashes can cure a person with gu poisoning. Moreover, the text provides a set of correspondences that act in concert: an illness caused by snake gu could be cured by centipede gu; an illness caused by centipede gu could be cured by toad gu; an illness caused by toad gu could be cured by snake gu. The remedies worked because, the text reasons, “things of the same type can subdue each other.” According to this logic, gu vermin is both a malady and a cure.⁵⁴

Gu Witchcraft

Gu was a medium of poisoning that often involved the manipulation of vermin and the defilement of food, but this was not the only way that gu poisoning was imagined and practiced. In many sources from the Han period on, it was also linked to witchcraft. Specifically, the term “shamanistic gu” (wugu) appeared frequently, referring to various methods of black magic that were deployed to harm the victim.⁵⁵ In an often-recounted episode that took place during the Western Han period, a trusted officer of Emperor Wu (reigned 141– 87 BCE) accused the prince (and heir apparent) of preparing a type of gu witchcraft that operated through a wooden puppet so as to make the emperor sick. Enraged by the accusation, the prince executed the officer, which further aroused the emperor’s suspicion. A bloody clash at the court ensued, leading to the death of thousands of courtiers and eventually the suicide of the prince.⁵⁶ The event became a watershed in the history of the Han dynasty, resulting in a reshuffling of political power and a sea change in the intellectual culture of the court. Although the accusation was unwarranted, gu represented a dangerous menace to the established order, eliciting keen anxieties and harsh actions.⁵⁷

Later sources offer more vivid accounts of gu witchcraft. A particular type of gu, called “the cat demon” (maogui), arose during the Sui dynasty and exerted profound influence on the political culture of the time. Let’s first turn to an episode that took place at the end of the sixth century, during the reign of Emperor Wen (reigned 581–604). Dugu Tuo, an official at the court, was interested in “the sinister way.”⁵⁸ Early on, his mother-in-law worshipped the cat demon and introduced the sorcery into Dugu’s household. Later, the empress and the wife of a high-ranking general named Yang Su both fell sick. When physicians were summoned, they all diagnosed it as an illness characteristic of the cat demon. Considering Dugu’s special position—he was the half-brother of the empress, and his wife was the half-sister of the general—the emperor questioned him in private, but Dugu denied any involvement. Still suspicious and unhappy with his reluctance to cooperate, the emperor dispatched a group of officers to investigate the case.

Eventually they identified a maid in Dugu’s house named Xu Ani, who came from the family of Dugu’s mother-in-law. She confessed that she worshipped the cat demon and possessed the power to conjure up the spirit, which could kill a person and secretly transfer the property of the victim to the murderer. She further admitted that early on, Dugu asked her to cast the cat-demon curse on the empress and the general’s wife so he could seize their riches. And so she did. After hearing her confession, one officer asked the maid to summon the cat demon back. At midnight, she set up a bowl of fragrant porridge and tapped on it with a spoon. She then called out, “Come, Cat Lady! Don’t stay in the palace anymore!” After a while, her face turned completely pale, and she acted as if she were being pulled by someone: she announced that the cat demon had returned. Upon hearing the result of the investigation, the emperor severely punished Dugu and his wife.⁵⁹

This account of the cat demon reveals much about its entanglement with the political life of the Sui court. Let’s start with the witchcraft itself. As disclosed by the maid Xu, the practice involved a furtive ritual of conjuring up a demon that inflicted sickness on victims over distance, usurping their wealth. This connection between gu and demons in general is not surprising, as we have already seen it in the work of Chao Yuanfang, but what is singular in this episode is the appearance of a demon in the form of a cat. How to make sense of a feline association with gu? In his On the Origins and Symptoms, the Sui physician explains that the cat demon is the spirit of an old, wild cat (li) turned into a demon and attached to human beings.⁶⁰ Malicious people store and worship the demon, a typical way of manipulating gu, to harm others. The symptoms of cat-demon attack are piercing pains in the heart and the abdomen; the demon would devour the viscera of the victim, leading to death from spitting or discharging blood.⁶¹

Chao’s depiction of the cat demon manifests the ever-changing nature of gu, particularly transformations between wild animal and demon. It is important to note that the line between the two was not clear-cut in premodern China. Early Chinese sources often portray animals as living beings with magical powers they could embody through protean transformations rather than merely biological entities.⁶² This is not surprising given the danger posed by animals, especially by ferocious and poisonous animals such as tigers and snakes, to those who ventured into the wilderness. Gu was an example par excellence for this type of imagination—the roaming spirits of wild animals, ever ready to morph into malign demons. Vicious people manipulated these demons, turning them into gu, which could inflict grievous harm on the targeted victims.

Yet the prominence of the cat in this particular type of gu still requires explanation. The portrayal of wild cats in Chinese sources, at least before the tenth century, was mainly negative. Although domesticated cats, since their introduction to China from India during the Era of Division, were valued for practical purposes, especially warding off mice, wild cats were believed to be sly, unpredictable, and inauspicious, often possessing uncanny powers.⁶³ The fear of cats penetrated the highest echelons of society. In 655, Empress Wu issued an order forbidding cats in the palace because a consort whom the empress had imprisoned vowed a magical revenge against the injustice of her persecution: the empress would turn into a rat and the consort into a cat, ready and able to pounce. Although there is no direct evidence of the practice of the cat demon in this episode, it nonetheless reveals anxiety about devilish feline creatures that could undermine, if not overturn, the political order.⁶⁴

Which brings us back to the story of Dugu. What was the political significance of this dramatic event? Why would Dugu want to poison the empress? The ostensible reason is that he ran short of money, but this is unlikely given his position at the court. Another possibility, suggested by previous studies, is that Dugu devised the sinister plan as a result of family tensions, particularly his jealousy of the empress, who was his half-sister. In earlier days, upon the death of their father, Dugu’s family line had enjoyed prominence, since his mother gave birth to six sons. By contrast, his half-sister remained obscure, as she was the only child of her mother. The situation was reversed when the latter became empress in 581, which suddenly raised the status of her family line. This could have elicited Dugu’s resentment toward his now-illustrious half-sister. A similar kind of familial resentment may also explain the poisoning of the wife of Yang Su, who was the half-brother of Dugu’s wife and a powerful regent at court. Being jealous, Dugu’s wife could have deployed the black magic to curse her nemesis.⁶⁵

It is also possible that Dugu and his wife were innocent, and the whole accusation was a conspiracy forged by their political enemies to slander and destroy them. The suspect is Yang Su, who was an ambitious general and a trusted confidant of the crown prince. According to The History of the Sui (Suishu, 636), he conspired with the prince to advance a case of witchcraft against one of the latter’s brothers, who was rising, threateningly, as a rival, leading to the victim’s demotion. The Machiavellian general may even have participated in murdering the emperor to help the impatient prince ascend the throne.⁶⁶ Given his record of trickery, it would not be surprising that Yang contrived the whole witchcraft trial to defame and eliminate Dugu.

The mystery of the cat demon scandal remains unresolved, but we know that the state acted swiftly. Initially, the emperor ordered the execution of Dugu and his wife. In response to the pleading of Dugu’s brother, he later reduced the penalty to stripping him of his royal position and sending his wife to a convent, a typical punishment for royal women at the time. He also commanded that Dugu’s mother-in-law, who was blamed for dispatching the cat demon to kill many people, be banished. Furthermore, the emperor issued an edict in 598 that all families who were accused of practicing cat-demon witchcraft be banished to the remote edges of the empire.⁶⁷

This strong political response to cat-demon witchcraft generated a snowball effect that powerfully shook the country over the next two decades. A seventh-century source provides a sober depiction:

During the period of Daye of the Sui [605–618], the affair of the cat demon broke out. Some families raised old cats and used them for sorcery, which had quite magical effects. People falsely accused each other [of practicing the sorcery]. Those who were embroiled in the affair and executed in the capital region and in the various prefectures amounted to thousands of families. The Duke of Shu, Yang Xiu, was implicated as well.⁶⁸ Once the house of the Sui collapsed, the affair also subsided.⁶⁹

Just like the capricious gu that came and went on a whim, cat-demon witchcraft was ephemeral in Chinese history, coinciding with the rise and fall of the short-lived Sui dynasty. Although the widespread persecution of witchcraft may not be the only cause of its collapse, it played an important role in the process, given that these scandals triggered violent court struggles that substantially destabilized the empire.

The state suppression of cat-demon witchcraft and gu practices in general continued after the fall of the Sui reign. In the Tang period (618–907) that followed, the court established stringent laws punishing gu practitioners. According to The Tang Code (Tanglü, 653), those who harbored and dispatched the cat demon and those who taught this black magic would be hanged. If someone practicing sorcery was discovered within a family, all would be exiled to faraway places, even if other members were unaware of her practice. The chief of the precinct in which the accused lived was also banished.⁷⁰ Inheriting the Sui model, the Tang state adopted harsh measures to eliminate practitioners of gu magic in order to maintain the political order.

Under severe persecution, accused sorcerers were pushed to the peripheral regions of the country. During the Sui-Tang period, this meant primarily the districts south of the Yangzi River. The climate, geography, and local customs of this region were vastly different from the north: it was warm and damp, full of mountains, rivers, and lakes, and associated with the widespread popularity of shamanistic practices. In the eyes of the Sui and Tang rulers, who were of northern origin, the region was uncivilized, mysterious, and dangerous, teeming with poisonous creatures and unruly barbarians.⁷¹

A connection between poison and heat can be traced back to antiquity, yet it found new expression in the seventh century with the linkages to gu in the south. The History of the Sui, for example, identifies ten districts where gu practices prevailed, all of which were located south of the Yangzi River.⁷² This southern proliferation of gu practices was partly due to the political expulsion of the practitioners, as just discussed. The mysterious, capricious nature of gu and its practices matched up well with the perception of the south as a strange, dangerous environment, abundant with vermin, real and imagined, readily identified as plentiful material for these practices. Gu became a perfect embodiment of the south, remote, unfamiliar, and intractable, and the source of serious challenges to state governance.⁷³

A salient aspect of the Dugu episode is the involvement of women. Although the central figure of the story is Dugu Tuo, a male official, he was surrounded by a number of women from distinct social backgrounds. These include the wife of Dugu, who—or so we are told—conspired with her husband to devise the sorcery; the two victims, that is, the empress and the wife of Yang Su; Dugu’s mother-in-law, who allegedly introduced the cat demon into his household; and last but not the least, the maid Xu Ani, who confessed to having performed the witchcraft. The last figure merits our attention, as all the other women in the story enjoyed lofty social status because of their ties to the imperial house. The maid Xu, by contrast, was merely a servant who was brought into Dugu’s house by his mother-in-law. Ani was not a formal name—there is doubt she ever had one—but rather a sort of calling often assigned to servants. Moreover, in the incantation she chanted to call back the cat demon, she referred to the creature as “Cat Lady” (Maonü), a colloquial turn of phrase that betrayed her lowly upbringing.⁷⁴ In addition, when the maid claimed that the demon had returned, her face changed color and she lost control of her body as if she were being pulled, indicating that she was possessed by a spirit. All the descriptions suggest that she acted as a shaman (wu) who performed a ritual to manipulate the cat demon.

The link between women and shamanism in China can be traced back to the Han period, if not earlier. Having a body that was considered to be more susceptible to external influences and hence easier to be put into a trance, women conducted a variety of shamanistic practices in antiquity. Submitting their bodies to willful spirits through possession, they acted as a crucial medium between numinous powers and human targets. Harnessing techniques such as incantation, spitting, and dancing, they performed rituals that aimed to either obtain benefits, such as healing by calling down deities or the cursing of victims through the manipulation of demons, as evidenced in the case of Dugu. In general, they came from the lower echelons of society and were portrayed as ignorant, incapable, and even dangerous. The energy that elites from the Han to the Tang period spent denigrating them indicates that they were fierce competitors and popular figures. Due to their undistinguished backgrounds—the majority of them were probably illiterate—little is known about these women’s lives. Yet occasionally they surface in our sources, such as the vivid depiction of Maid Xu in the examined episode, offering us a rare glimpse of their practices.⁷⁵

Conclusion

A popular saying today aptly summarizes the logic guiding the use of potent drugs in medieval China: use poison to attack poison (yi du gong du). Although the expression first appeared in a thirteenth-century text, the idea it conveys has much deeper roots.⁷⁶ The first “poison” in the phrase refers to potent medicines; the second designates poisoning, and illness in general. The word “attack” (gong) carries two meanings. First, it expresses the violent nature of the remedy. Because the sickness is obstinate, one must apply powerful drugs to eradicate it. Second, the word implies a specific and concrete target that the medicine can latch onto and destroy. The logic of potent treatments was thus linked to a particular way of understanding illness. That is, physicians prescribed poisons as powerful weapons to eliminate tenacious illnesses that often assumed concrete forms, be they demons or gu vermin. These malignant entities, which either attacked the body from the outside or ravaged it from within, could induce severe symptoms and trigger deadly epidemics. Poisons were thus used to strike these virulent beings and purge them from the body.⁷⁷

The scholarship on etiological studies provides valuable insights into the understanding of demons and gu in Chinese medicine. Previous work on the conceptualization of disease in the history of Western medicine has identified two major models: the ontological, which regards disease as a kind of entity that invades a healthy person, and the physiological, which views disease as a deviation from the normal state of the body.⁷⁸ Similar models were proposed within various traditions of Chinese medicine: the ontological approach imagined illness as a concrete agent located at a specific site of the body, while functional orientations saw illness as the aberrant flow of qi inside the body and the discordance between the body and the cosmos.⁷⁹ The functional model, exemplified by The Yellow Emperor’s Inner Classic, stresses the importance of harmony and balance in maintaining good health. Since an illness in this model is the result of a body out of kilter, it can be rectified by readjusting the body to the normal state. By contrast, the practice of poisons highlights the ontological model in the imagination of illness during medieval China. In this scenario, illnesses assume concrete forms that are inimical to the body, manifested either as malign agents in nature (demons) or as dangerous creatures prepared by vicious minds (gu vermin). They cannot be harmonized or rebalanced; they must be expelled or destroyed.⁸⁰

Furthermore, the medical use of poisons and its underlying etiological rationale had far-reaching political implications in China. Medical writings from the Han period onward conceptualize a system of correspondence that emphasizes the resonance between the individual, the state, and the cosmos. With its focus on harmony and balance, the model presents an ideal body that enjoys physical vigor and social stability. The cases of gu witchcraft during the Sui-Tang period, however, present a different scenario. The mysterious and elusive practices elicited great anxiety at court and beyond, and served as justification for strong political action. Similar to physicians’ use of potent medicines to eliminate malign forces from the physical body, the state established stringent policies to expel gu practitioners themselves, many of whom were women, to sustain a healthy social body. The process continued after the Tang dynasty. As a result, those convicted of practicing gu witchcraft were increasingly pushed to the margins of the empire, first to the south, later to the southwest. During the late imperial era, gu also became associated with minority peoples, especially the Miao.⁸¹ Despite continuous persecution, gu practitioners were never entirely eliminated—we still have ethnographical accounts of their practices today.⁸² Hiding in faraway lands, lurking at the edges of empire, they remain a menace to the established order.

The short-lived Sui dynasty was succeeded by the Tang, a powerful and cosmopolitan empire that inherited some of the Sui government’s institutional and legal measures on medical regulation but with substantial expansion and changes. In particular, pharmacology flourished in the early Tang period; the court in the seventh century established new institutions, developed a tribute system, and sponsored authoritative texts to collect drugs and standardize the knowledge regarding their use. Such knowledge produced at the political center then quickly spread throughout the empire and underwent fluid transformations in local communities.