Formula Books from the Han to the Tang Period

The writing of formula books in China can be traced back to the Han period. The bibliographical section of The History of the Han places these books in the category of “classical formulas” (jingfang), which constitutes one of the four types of treatises on healing.⁷ There are eleven titles in this group, most of which focus on treating specific types of illness, such as wind-induced fever and chills, internal injuries, and gynecological or pediatric disorders. It also includes a treatise on dietary taboos, indicating the awareness of food poisoning at the time. All of these texts, however, were lost long ago. In a different context, we find a collection of about three hundred formulas preserved in the Mawangdui medical manuscripts dating to the second century BCE. These texts provide simple cures, which often combine the use of drugs with spitting and incantations, to treat fifty-two types of maladies.⁸ A smaller set of formulas was also discovered in manuscripts excavated from Wuwei and dating to the Eastern Han period. In these, the magical power of remedies is less prominent, suggesting regional differences in healing practice during the Han dynasty.⁹ Poisons appear frequently in these formula collections: aconite of varying strengths (wuhui, fuzi, tianxiong) was one of the most often used medicines. The authors of these manuscripts remain unknown, and we find no trace of their voices therein.

During the Era of Division, medical culture flourished with the rise of hereditary medicine practiced by aristocratic families, especially in the south.¹⁰ Formula books proliferated in this period. Although none of these works are extant in their entirety, many of their titles entered the bibliographies of the Sui and Tang official histories. The History of the Sui, for example, holds more than one hundred titles of formularies.¹¹ Significantly, many of these texts were ascribed to specific authors. These include the Han physician Zhang Zhongjing (150–219), the alchemist Ge Hong (283–343), the Daoist master Tao Hongjing (456–536), and several Buddhist monks. The rise of authorship indicates the effort of medical writers of various social backgrounds to produce formularies to enhance their reputation and establish authority. In particular, a number of these texts were compiled by the Xu family, who had practiced healing continuously for eight generations, suggesting the prominence of hereditary medicine during this period.¹² Moreover, ten titles carry the word “efficacy” (yan or xiao). Some of these texts were attributed to a single author or a family, such as Tao Hongjing or the Xu family. Others were collections of remedies from multiple sources, as suggested by the appearance of the term “collected efficacious formulas” in the title. The criteria according to which the efficacy of a formula was assessed is not made clear in the texts, yet it is evident that medical writers at the time valued the therapeutic outcome of their remedies.

The following seventh and eighth centuries witnessed the end of political division and the rise of the powerful Sui and Tang empires. In this new environment, the state became more active in compiling and circulating medical works, including formula books. For example, the Sui court issued a massive Assorted Collection of Formulas from the Four Seas (Sihai leiju fang), which contained 2,600 scrolls. Impressively comprehensive, the work probably served more to showcase the majesty of the empire rather than to guide medical practice. The court also sponsored an abridged version of the unwieldy book, which included only single-drug remedies in three hundred scrolls. It is more likely that this shortened text was used in practice.¹³

The Tang court also valued formula books and incorporated them into medical education. According to an eighth-century ordinance, students in the department of medicine at the Imperial Medical Office were required to study medical canons of acupuncture, pulse examination, and materia medica, as well as three others: a formula book of Zhang Zhongjing, Formulas of the Lesser Grade, and Collected Efficacious Formulas.¹⁴

Zhang was a physician during the Eastern Han dynasty known for treating “cold damage” disorders, a set of acute and often severe conditions characterized by fever. Although Zhang’s status was substantially elevated in the Northern Song period (960–1127) thanks to the state’s effort to systematize his writings on the treatment of epidemics, the Tang government in the eighth century already considered his works indispensable for medical learning. It is unclear which of Zhang’s works the ordinance refers to—there are four formula books attributed to the Han physician in the bibliographical section of The History of the Sui, but suffice it to say that Tang medical training prized the remedies of a respected voice in the past.¹⁵

Second, Formulas of the Lesser Grade (Xiaopin fang) was a fifth-century work by Chen Yanzhi. It offered a collection of formulas for those who encountered medical emergencies where no expert care was available. In the preface, Chen describes formularies as works of a “lesser grade” compared to the theoretical texts, which he deems to be of a “greater grade.” He further suggests a sequence for studying these texts: beginners should start with texts of a lesser grade to gradually reach the level of understanding that would allow them to grasp works of a greater grade. Empirical knowledge was a gateway to learning complex theories. With this goal in mind, Chen stresses the importance of understanding materia medica, especially knowledge of the properties of drugs that would inform their use in formulas. The Tang government chose this text for medical training probably because it effectively linked practical knowledge to doctrinal learning.¹⁶

The third text, Collected Efficacious Formulas, was likely produced based on the perceived effectiveness of its remedies, as indicated by the word “efficacious” in the title. The text could refer to one written by the sixth-century physician Yao Sengyuan because he compiled a book with exactly the same title. Yao came from an aristocratic family in the south that had been practicing medicine for many generations. Famous for his talents as a physician, Yao served as a high official at the courts of both the southern and northern dynasties. His formula book, which he compiled at the request of many who were seeking effective remedies, enjoyed lasting popularity, as Tang medical writers frequently cited his prescriptions for treating diverse disorders. The inclusion of this text in imperial education signifies the Tang court’s attention to the efficacy of remedies, which could be detached from theoretical thinking.¹⁷

Sun Simiao and His Formula Books

None of the formula books discussed above are extant in their entirety. Nevertheless, several complete works of this genre from the early Tang period are still available, allowing for an in-depth analysis. In particular, Essential Formulas by Sun Simiao (581?–682) is significant, as it contains twenty-five medical cases scattered throughout the book, revealing how the physician integrated practice-based knowledge into his medical writing.

Sun, “the King of Medicines,” was one of the most famous physicians in Chinese history; he collected a great number of drug remedies, some of which became standard treatments in the healing repertoire throughout imperial China and beyond.¹⁸ Already a well-known figure in his lifetime, Sun gained more fame in the eleventh century, when the state enshrined his two formula books in the official canon. He was also deified during the Northern Song period, when the court granted to him the Daoist title of “the perfected” (zhenren).¹⁹ Although the image of Sun as the greatest physician of all time would begin to dominate from the Song dynasty on, it is important to point out that during the Tang period, he was revered as a master who had versatile skills in medicine, alchemy, fasting, the cultivation of longevity, and divination. Rather than a medical specialist, Sun possessed broad knowledge of the arts of living.

Sun was born in the northwest, near the Tang capital Chang’an, sometime in the late sixth century.²⁰ Unlike some prominent physicians during the Era of Division, he did not come from an aristocratic family of medical heritage. He probably grew up in a comfortable setting, though, as both his grandfather and his father served as officials of different ranks in the northern dynasties.²¹ According to the preface of his Essential Formulas, he obtained medical knowledge chiefly through self-study. When he was young, he had often been ill. Because visiting doctors was costly, he started to study medicine himself through extensive reading of the classics. At the age of twenty, feeling that he had grasped the essential knowledge of healing, Sun began to treat his relatives and neighbors, through which he gained practical experience. His reputation soon grew.

Based on his biographies in the two official histories of the Tang dynasty, it appears that Sun was not keenly interested in pursuing a political career; in his long life, he was asked by several emperors of a succession of dynasties to serve at court, but he declined the offers time and again. Understandably, in these biographies, he was placed in the category of either “[people possessing] methods and techniques” (fangji) or “recluses” (yinyi).²² Yet beneath the façade of being a talented hermit uninterested in politics, he remained connected to the court. Summoned by Emperor Gaozong in 658, he took the position of assistant director in the Palace Drug Service, which offered technical guidance on the preparation of medicines for the imperial family. Given that this was the moment when the court was compiling Newly Revised Materia Medica (see chapter 4), it is possible that Sun was consulted in the making of the pharmacopoeia. During his stay in the capital, he was also socially active, offering medical service to court officials and befriending scholars who admired his wisdom.²³ According to a newly excavated tombstone that preserves the epitaph for one of Sun’s sons, the physician “dwelled at the center of the court, and his aspiration extended to the faraway seas.” The contrast encapsulates the image of a Sun who moved between public and private spaces, and negotiated with political resources to enhance his reputation as a superb doctor and fulfill his pursuit of the arts of healing.²⁴

Furthermore, Sun was familiar with Daoist and Buddhist teachings. He was particularly interested in the techniques of life cultivation and spent two years at Mount Taibai not far from the capital, learning the methods of refining qi and nourishing the body. He also had advanced knowledge of alchemy, which he put into practice. Sun’s Buddhist knowledge came from his extensive reading of scriptures and interaction with several eminent monks, from whom he acquired unusual formulas and mastered the technique of ingesting water.²⁵ Buddhist influence is also evident in his medical ethics: he embraced the idea of treating patients compassionately regardless of their social status, echoing Buddhist teachings of equality and universal salvation. This spirit is palpable in Sun’s formula books, where he offered varying remedies using expensive or ordinary ingredients to patients of noble or humble origins, respectively.²⁶

Sun compiled two formula books later in his life: Essential Formulas in the 650s and Supplement to Formulas Worth a Thousand in Gold (Qianjin yifang; hereafter, Supplement to Formulas) in the 680s. The latter text, which he completed not long before his death, is more miscellaneous, incorporating a wide range of healing methods, such as fasting, alchemy, and incantations. He also included many formulas for prolonging life, probably because of his old age.²⁷ Unlike the court-commissioned Newly Revised Materia Medica, Sun’s two formula books reveal no trace of the state’s direct intervention. However, given Sun’s close ties to the court, it is conceivable that he had access to resources in the imperial library to compile his books. The affinity is particularly evident in his Supplement to Formulas, in which he copied verbatim the description of drugs from Newly Revised Materia Medica. The standardization of drug knowledge by the Tang government hence readily entered into Sun’s medical writings.²⁸

Essential Formulas contains thirty scrolls.²⁹ The first scroll offers general therapeutic guidelines, including diagnosis, prescription, and the preparation of drugs. The following scrolls are organized by types of illness. In each of them, Sun starts with a theoretical discussion of the illness, expounding its causes, symptoms, and bodily dynamics. This is followed by a large number of drug prescriptions that treat the illness, as well as a few moxibustion remedies at the end. Altogether, the book contains more than 4,200 drug remedies. In the preface, Sun explains his purpose in compiling these formulas:

I find that all formula books are massive volumes. If one suddenly encounters an emergency, it is very hard to seek the remedy. By the time the formula is acquired, the illness has already become incurable. Alas! I agonize over the calamity of untimely death and lament the follies caused by crude learning. I then widely gathered various classics. I deleted the complicated formulas and made sure to keep the simple ones, thereby producing one book of Essential Formulas Worth a Thousand in Gold for Emergencies. Altogether it has thirty scrolls.³⁰

Recognizing the difficulty of handling voluminous tomes, Sun selected “essential formulas” from earlier works that could be readily used in emergencies. This criterion evinces the practical orientation of his book: it was composed not to display scholarly erudition but to cure illness. The title of the book expresses the attitude well; he asserts that since a human life is extremely valuable, with its worth over a thousand in gold, the virtue of saving it by a formula even exceeds that value.³¹ Sun was not alone in this aim. According to the bibliographical records, a number of physicians and scholar-officials during the Tang period compiled formula works whose titles contained “for emergencies.” Easy use of remedies to treat acute conditions, therefore, was a widespread pursuit at the time.³²

Although Sun emphasizes the practical function of his book, he still respects established doctrines. At the beginning of each scroll, he explains the nature and symptoms of the illness, starting with the set term “discussion” (lunyue), which is likely Sun’s own voice. Such discussions are often framed in the conceptual schemes of yin and yang, the five phases, and qi, which characterize the illness as dynamic processes correlated with the environment.³³ Sun also frequently counts on authoritative voices to bolster his propositions. Among them, the words of Bian Que, a semimythical physician living in antiquity, appear most often—Sun cites him more than thirty times.³⁴ Other sources that appear in Sun’s theoretical discussion include passages from the ancient physicians Zhang Zhongjing, Wang Shuhe, and Hua Tuo, as well as from the Han classics The Divine Farmer’s Classic and The Yellow Emperor’s Inner Classic. Sometimes he also cites more recent works, such as Formulas of the Lesser Grade (fifth century).³⁵ It is clear that Sun relied heavily on classical wisdoms in his conceptualization of illness.

Less obvious, though, is how Sun fit specific drug remedies into this theoretical framework. At the beginning of the book, he does include a section on the basic rules of making prescriptions, but the discussion is short and generic, primarily based on The Divine Farmer’s Classic. For example, he presents the principle of opposites, namely, to use warming drugs to treat cold maladies and vice versa.³⁶ But the rule is probably too crude to explain the composition of many complex formulas in the book that contain multiple ingredients. Moreover, driven by his goal for easy use, Sun includes a large number of single-ingredient formulas that deploy ordinary substances, such as soil, foods, and feces, to treat emergencies.³⁷ Such remedies cannot be easily explained with the conceptual program that Sun inherited from classical texts. And he makes no effort to offer such an explanation. Therefore, despite the physician’s attention to ancient medical principles, his formulas, which are abundant and eclectic, are largely detached from doctrinal teaching.

For whom did Sun write the book? Repeatedly, he uses the generic appellation “learner” (xuezhe) to address his readers. More specifically, he states in the preface that the book “may not be possible to be transmitted to scholarly groups, and I only wish to pass it on in private lines.”³⁸ These “scholarly groups” (shizu) could refer to certain prestigious aristocratic families that had practiced medicine for generations or scholar-officials who were personally interested in medicine and exchanged medical knowledge within their circles. Given Sun’s humble origins, his stated intention to keep his book within private confines—be it in his family or among his disciples—could have been a tactic to enhance the value of his work against powerful competitors. The idea of private transmission was not new—the phenomenon can be traced back to antiquity when medical learning often passed from masters to disciples in a secretive and ritualized fashion.³⁹ In fact, many formulas in Sun’s book, especially those with claimed efficacy, end with the leitmotifs of “keep it secret,” “do not transmit it,” or “do not transmit it even for a thousand in gold.”⁴⁰ Although it is hard to tell whether these are Sun’s own words or what Sun copied from earlier sources, the frequent association of such expressions with his formulas indicates the physician’s intention to limit their circulation.

That being said, Sun remained open to the court. In several medical cases that recount his own experience, he calls himself “your servant” (chen), the appropriate form of self-reference for a minister when speaking to the monarch. Given Sun’s strong connection to the court, he could have borne the emperor in mind when he compiled the formulary. This intent would not necessarily conflict with his emphasis on private transmission; the value of his work precisely lay in its availability only to the highest powers. Although the text was not selected for imperial medical education, it gained recognition in Sun’s official biography and the bibliographical record of the Tang dynasty.⁴¹

“Efficacious” Remedies in Essential Formulas

Besides the doctrinal teaching at the beginning of each scroll, Sun provides a large number of formulas that treat the illness under discussion. In general, the writing of each formula follows a set pattern. It starts with the name of the formula, often with the typical symptoms associated with the illness for which it is indicated. It then lists all the ingredients in the formula, specifying the dose for each one. Finally, it advises how to prepare and administer the formula. Sometimes, the description ends with a statement of the efficacy of the medicine. The size of the formulas in Sun’s book varies greatly, ranging from single-drug remedies to enormous prescriptions that use as many as sixty-four ingredients. Almost all from the former group are applied topically to treat sores, swellings, and wounds. Those from the latter group, by contrast, often work as panaceas to eliminate obdurate maladies and restore the vitality of the body.⁴² The following is an example that treats a gynecological disorder and triggers pregnancy:

Formula of the White Vetch Pill from the magistrate of Jincheng. It cures blockage and stagnation of menses that leads to the inability to become pregnant for eighteen years. Upon ingesting this medicine for twenty-eight days, a woman will bear children.⁴³

White vetch (five liang), ginseng (three fen), southern asarum (three fen), bull dodder (three fen), achyranthes (two fen), asarum (five liang), magnolia bark (three fen), pinellia (three fen), adenophora (two fen), dried ginger (two fen), infected silkworm (three fen), gentian (two fen), pepper of Sichuan (six fen), angelica (three fen), aconite (six fen), saposhnikovia (six fen), purple aster (three fen).⁴⁴

Mix the above seventeen ingredients with honey to make into pills. First ingest three pills the size of a seed of the parasol tree. If the patient does not feel the effects of the medicine, slightly increase the dose to four or five pills. This medicine should not be ingested for long. The patient should stop using it when she suspects that she has become pregnant. Greatly efficacious.⁴⁵

The formula uses seventeen drugs, mainly of herbal origins, to treat a menstrual disorder. Among them, three possess du (pinellia, pepper of Sichuan, and aconite). Sun recommends that the patient gradually increase the dose until she feels the effects of the medicine, indicating the importance of bodily sensations in gauging the therapeutic outcome.⁴⁶ It also warns against the excessive consumption of the medicine, probably due to the presence of the potent ingredients. A powerful medicine, in other words, must be cautiously administered.

Where did Sun obtain his formulas? The one above is attributed to the magistrate of Jincheng, a prefecture in the northwest (present-day Lanzhou) that was established in the Western Han period. It is unclear whether the magistrate was a contemporary of Sun or lived long before. In the latter scenario, Sun probably copied the formula from an earlier source.⁴⁷ Identification of a formula’s originator, however, is rare in Sun’s work; for the majority of his prescriptions, he simply wrote down their content without acknowledging the source. This is in sharp contrast to the theoretical sections of his book, in which he frequently cites ancient authors to buttress his discussion. Since Sun’s work contains a massive number of formulas, he probably copied most of them from other texts, which the physician readily acknowledges in the preface. But the lack of mention of the origins of the formulas implies that he prioritized the practical value of healing over the scholarly production of knowledge.

What were the criteria for Sun to include a formula? In the introductory section on treating pediatric disorders, he first exposes the limitations of the formulas from the powerful Xu family, revealing his critical attitude toward aristocratic medicine. He then lays out the two basic principles for compiling his own formulas: to gather them widely from all schools of medicine, and to include those that prove “efficacious upon self-usage” (zi jingyong youxiao).⁴⁸ On the one hand, Sun’s work is decidedly eclectic; it was compiled based on a comprehensive survey of available sources without subscribing to a particular lineage. On the other, Sun stresses the importance of personal experience in validating the efficacy of his formulas. In another section discussing hot diarrhea (reli), he declares that he could not record thousands of formulas that treat the disorder from ancient and contemporary sources. Instead, he picked only seven or eight among them that had proven efficacious.⁴⁹ Therapeutic efficacy therefore was a crucial criterion for the physician when selecting remedies.

Yet we must not hasten to associate the claimed efficacy of a remedy with Sun’s own practice. In the sample formula presented above, the term “greatly efficacious” appears at the end, praising the success of the treatment. How do we make sense of it? Throughout Essential Formulas, we find many similar expressions attached to the end of prescriptions, which almost always include words for efficacy (yan, xiao, liang). Some of the most frequent phrases are “spectacularly efficacious,” “spectacularly good,” “extremely good,” and “having efficacy.” Other expressions, though not including the word “efficacy,” convey a similar meaning, such as “no single failure upon trying ten thousand times” and “as if pouring hot water onto snow.”⁵⁰ These “efficacy phrases” are terse, generic, and formulaic. They carry the rhetorical force of a boast rather than serving as evidence of the remedy’s actual use.⁵¹ A heightened attention to efficacy is already detectable in formula books during the Era of Division, as evidenced by the increasing appearance of the word in their titles. These earlier works also include “efficacy phrases” tagged to the end of some of their formula entries, undoubtedly serving the same rhetorical function.⁵² Very likely, Sun incorporated these earlier formulas, including the set terms, into his book without voicing his own opinion. Efficacy was an artifact of copying.

Medical Cases in Essential Formulas

The most salient feature of Essential Formulas is the medical cases embedded in the prescriptions. No earlier formula books include such cases, making Sun’s compilation a new phenomenon in the history of medical writing in China. Close study of these twenty-five cases illuminates the meaning of efficacy and the role of personal experience in the making of new medical knowledge.⁵³

In general, each medical case appears at the end of a formula, in which Sun presents a specific situation to testify to the efficacy of the remedy. These cases contain some or all of the following components: the time, place, identity of the healer, identity of the patient, diagnosis, prescription, and therapeutic outcome. Although the majority of these narratives are based on Sun’s own experience, this is not always so. For example, in a case of curing “the dragon illness” (jiaolong bing), Sun records that on the eighth day of the second month in 586, someone ate celery and contracted the illness. The symptoms resembled those of a condition called “abdominal bloating,” with the face turning bluish yellow. Upon ingesting three liters of cooling foods and strong malt sugar, the patient spat out a dragon possessing two heads and a tail. It was a greatly efficacious cure.⁵⁴ The case confirms the efficacy of a simple food remedy to eliminate a pathological entity inside the body.⁵⁵ Revealingly, Sun did not identify who the patient was; he only used the generic phrase “someone” to refer to him or her, which suggests that he had no direct experience of the event described. He may have heard of the story from others and included it in his book to validate the formula. Efficacy could be disembodied knowledge bolstered by word of mouth.

The majority of the cases in Essential Formulas (twenty-one out of twenty-five), however, clearly show Sun’s personal involvement. Among them, he treated others in eleven cases and himself in ten cases. In the former category, he reveals the identity of his patients in three cases, which include two local noblemen and a nun.⁵⁶ The patients in Sun’s account usually do not have a voice—they are portrayed as passive recipients of the treatment. When they occasionally speak, their views are erroneous, often with serious consequences. In one case, a patient did not believe Sun’s diagnosis of his illness as foot qi because he found no sign of swollen feet. The misjudgment cost the man his life. In another case, a patient became sick upon ingesting minerals, a popular practice for nourishing the body at the time, and died after trying numerous self-administered formulas. Without a capable physician, one’s chances of surviving an intractable malady were slim.⁵⁷

Presenting himself as one such capable physician, Sun boasts of his healing skills by highlighting his extensive experience; he points out in one case that he treated more than a hundred patients with the intransigent illness of “great wind” (dafeng).⁵⁸ Among his twenty-five medical cases, thirteen designate the date when the healing occurred, sometimes down to a particular day. For the cases that Sun himself was involved with, the dates range between the years 605 and 643, which correlates well with the years that were probably the prime of his life, suggesting that Sun’s cases were built upon his own experience, rather than simply an artifact of his having copied earlier sources. With respect to the locations of healing, although Sun spent most of his life in the capital Chang’an and nearby regions, he also traveled to Jiangzhou (in present-day Jiangxi), Shuxian (present-day Chengdu), and Neijiang (in present-day Sichuan), where he attended a duke, practiced alchemy, and cured himself of a skin rash, respectively.⁵⁹

The last aspect merits our attention, namely, self-healing. Sun regularly tried medicines on himself and used the experience as compelling evidence for a formula’s efficacy; such instances appear frequently in the book (ten out of twenty-five cases). Sun’s narrative of self-healing is varied. Sometimes, the situation was urgent and his use of the right formula proved to be lifesaving. For example, when he was in Neijiang in 643, he became ill with a skin condition known as “vermilion poisoning” (dandu), a deep-red skin rash. The rashes first developed on his forehead and quickly spread to the rest of his body. He almost died. The county magistrate offered him various medicines, none of which worked. After seven days, Sun tried a single-drug formula of brassica paste, which cured him. He thus recorded the formula to make it widely known. Resolving a critical condition with a simple remedy undoubtedly testified to its value.⁶⁰

Moreover, Sun’s medical cases often build on a narrative of trial and error. In one revealing example, he presents a formula that uses the cocklebur paste to treat “clove swellings” (dingzhong), ulcerous lumps shaped like cloves. Cocklebur (cang’er) was a du-possessing herb that already appeared in The Divine Farmer’s Classic, where its fruit was valued for eliminating limb pain and nourishing the body. The authors of Newly Revised Materia Medica identified more uses of the herb to treat seizures, poison in marrow, and venomous stings.⁶¹ Although cocklebur was a well-recognized medicine during the Tang period, Sun’s use of it to treat clove swellings was novel. Specifically, he directs the users to incinerate the roots, stems, and sprouts of the herb, mix the ashes with vinegar, and apply the paste to the swellings. Once the paste is dry, they should replace it with another fresh preparation, repeating the process until it eventually pulls out the root of the swellings. The medicine is “spectacularly good.” Sun then relates that in 630, he suddenly had clove swellings at the corners of his mouth. He visited a person named Gan Zizhen, whose mother prepared a different paste for him, but the medicine did not work.⁶² He then tried the cocklebur paste, which cured him immediately. Afterward he often made this medicine for patients, and none had failed to be healed. Among the thousand formulas that treat clove swellings, Sun avers, none of them is better—even the trusted formula from Granny Rong of Qizhou (present-day Jinan) is not as powerful as his.⁶³ By contrasting the efficacy of the cocklebur paste with the failure of another treatment, Sun underlines the significance of trial and error in finding excellent cures. The formula he singles out at the end, Granny Rong’s, presumably a reputable remedy at the time, involves six ingredients and a long, complicated preparation process. Simple and effective, small wonder that the cocklebur paste became Sun’s favorite to treat clove swellings.⁶⁴

What illnesses appear in Sun’s medical cases? Although the case studies are spread throughout the thirty scrolls of Essential Formulas, we find two clusters formed around specific conditions: the wind-induced disorders, especially foot qi (juan 7 and 8), and swellings and abscesses (juan 23). The first cluster concerns acute, life-threatening conditions that demand swift action; the second includes illnesses with manifest external signs. A successful treatment of a disorder in these clusters yields immediate and unambiguous outcomes—the patient survives, the ulcers disappear—which clearly showcases the efficacy of the remedy.

Notably, Sun often prescribed potent medicines in his medical cases. In twelve of the twenty cases that involved drug therapy, he utilized du-possessing substances of herbal, mineral, and animal origin, including aconite, pinellia, croton, orpiment, and bovine bezoar. These drugs were often deployed to treat severe and obstinate conditions, such as hot, poisonous diarrhea and gu poisoning.⁶⁵ Sun also traveled to Shuxian to obtain the best materials for his alchemical practices. Fully aware of the danger of one key ingredient used in alchemy, realgar (an arsenic compound), he cautions that one must detoxify the potent mineral before using it for making elixirs.⁶⁶

One of the most frequently prescribed potent medicines in Sun’s formulas was aconite. The drug was considered particularly effective for treating sudden turmoil (huoluan), an acute condition caused by improper diet leading to the entanglement of pure and turbid qi in the stomach and intestines.⁶⁷ In one case, Sun recommends a formula that employs ten herbs, including two possessing great du—aconite and arisaema (huzhang)—to cure the severe disorder and prevent it from recurring. The ingredients are ground into powder, mixed with honey to make pills the size of a parasol tree seed, and taken with alcohol twenty pills a time, three times a day. Sun then continues with a story:

During the Wude period [618–626], there was a virtuous nun named Jingming. She suffered this illness for a long time. Sometimes the illness erupted once a month, sometimes more than once a month. Every time the illness erupted, she almost died. At the time, great physicians at court such as Jiang, Xu, Gan, and Chao failed to recognize the illness. I treated it as sudden turmoil and prescribed this formula, which cured her. I thus recorded the formula.⁶⁸

The story emphasizes Sun’s ability to correctly diagnose the patient. Revealingly, Sun contrasts his superb skills with the clumsiness of the court physicians, who, despite their high position, were unable to discern the illness. Many of these physicians came from medical families of aristocratic origin who entered the imperial medical bureaucracy during the early Tang period.⁶⁹ Sun did not belong to this select group of social elites, though he frequently interacted with them while staying in the capital (the aforementioned Gan Zizhen, from whom he sought treatment, might have been the same court physician named Gan in this story of the nun). He was generally critical of their healing expertise, often calling them foolish, coarse, or clumsy.⁷⁰ The disparaging tone implies an uneasy tension between medical practitioners of distinct social origins at the time. By pointing out the mistakes of his noble yet inferior contemporaries, Sun tried to carve out a space beyond hereditary and court medicine, elevating his reputation as a superb healer based on the evidence of his practice.

These case reports of Sun’s successful healing of both himself and his patients suggest that he had an excellent grasp of the relationship between the symptoms of an illness and the corresponding rationale for designing a formula to treat it. In other cases, however, he admits that his understanding of how a remedy worked was limited. This brings us back to the opening episode. In a section on panaceas, Sun depicts Genkwa Powder as a powerful medicine that can cure all illnesses of wind cold, the accumulation of phlegm, concretions and aggregations, and intermittent fevers, as well as those conditions that myriad physicians fail to cure.⁷¹ After a lengthy explanation of the various methods of preparing and deploying the cure-all, he reveals that the formula did not actually appear in any of the books he had read. Rather, he obtained it from a Buddhist monk named Jingzhi over thirty years before.⁷² During his days, no eminent physician sanctioned the use of the peculiar medicine, yet upon trying it, Sun found it spectacularly effective. He further reflects:

The way this formula uses drugs does not follow regular orders at all, and the rules of its ingestion are far beyond human reasoning. Yet as for treating emergencies, its efficacy is extraordinary. I then realized that the efficacy of spectacular things is not bound by common rules. The supreme principle of resonance cannot be fathomed by intelligence. This also resembles the situation when a dragon cries, clouds rise; when a tiger roars, the wind comes into being. This is without understanding why it is so—even sages cannot discern the reason.⁷³

What is striking in this passage is Sun’s ready recognition of the inadequate understanding of why the medicine works (buzhi suoyiran). Even sages, he avows, cannot comprehend the logic of the highest principle. This comment is in sharp contrast to his theoretical discussion of illnesses at the beginning of each scroll, which heavily relies on ancient wisdom and established doctrines. Here, however, his perspective is more open: there are things in the world whose ways of working are beyond human understanding. Yet as long as they can effectively treat emergencies, Sun finds no reason not to include them in his collection.⁷⁴ This practical sentiment is not just associated with large, complex formulas. In another case, Sun tried several remedies to treat sores that were caused by the urine of earwigs, but to no avail. He then learned the unusual method of drawing the shape of the insect on the ground, taking the soil enclosed by its abdomen, mixing it with saliva, and smearing the paste onto the sores. This simple remedy swiftly cured him, though he confessed that “myriad things under heaven resonate with each other, and I do not fathom the reason.”⁷⁵ Despite this, he cherished the formula because of its undeniable efficacy. For Sun, empirical knowledge outweighed doctrinal learning.

The practical orientation of Sun’s medical cases is also indicated by how he treated patients of different social origins. Likely due to Buddhist influence, Sun embraced the spirit of treating all people equally, whether the person was “noble or ordinary, poor or rich, old or young, beautiful or ugly, enemy or friend, Chinese or barbarian, stupid or wise.”⁷⁶ This ethical principle required a physician to treat patients regardless of their social status—but this does not mean that the same remedy was appropriate for everybody. For example, in the section on treating cold diarrhea, Sun offers two formulas for the nobles, both to restore the vitality of the Spleen.⁷⁷ The first, the Spleen-Warming Decoction, is a generic prescription to treat either cold or hot diarrhea, using rhubarb, cinnamon, aconite, dried ginger, and ginseng to induce draining in the stomach. The second, the Spleen-Strengthening Pill, is specific for cold diarrhea. It contains fifteen ingredients, including stalactite, coptis, ginseng, dried ginger, cinnamon, and aconite, that aim to nourish the Spleen to facilitate its full recovery. However, Sun notes that it was hard for the poor to prepare these formulas, likely because of the cost of certain ingredients.⁷⁸ Moreover, the two formulas work in concert: the first to eliminate the illness, the second to nourish the body and restore its strength. The latter requires sufficient rest with a proper regimen—a remedy that is compatible with the leisurely lifestyle of the nobility. Not just money but time was a luxury that the poor did not necessarily possess.⁷⁹

Conversely, Sun considers certain remedies inappropriate for the nobles. In a formula that treats welling abscess (yongzhong), Sun proposes making a paste out of a chicken egg and fresh human feces and applying it to the pus. He comments that the formula is filthy, so it should not be applied to the nobles. Yet as for its power to cure this illness, the medicine is second to none. Other formulas, by contrast, just follow the protocols and abide by the rules; hence people should be aware of this unique remedy, which could treat them effectively in case of emergency.⁸⁰ Sun considers certain ordinary substances—human excrement in this case—too filthy for elites but acceptable for the less privileged. Medicines were social substances.⁸¹ Yet the efficacy of the formula was beyond doubt despite its unusual ingredient. Comparing it with conventional formulas that better fit established frameworks but were less effective, Sun makes it clear that he prefers utility to conformity.

Conclusion

What does Sun’s Essential Formulas tell us about the relationship between text and experience in Tang China? His book contains over four thousand prescriptions, so it is hard to imagine that he tested all of them himself. Rather, he followed a long tradition of copying formulas from earlier and contemporary sources, though he rarely specified the titles of these texts. The frequent appearance of the “efficacy phrases,” which are mechanical, repetitive, and nonspecific, signals that such copying served to rhetorically promote his remedies. That being said, Sun’s text is not merely an artifact of replication but reveals something important about empirical knowledge. In particular, his twenty-five medical cases, which are concrete and detailed, underscore the value of personal experience in his assessment of formulas. Although Sun cherished doctrinal principles and the voices of ancient authorities, he recognized their limitations and prioritized the efficacy of remedies based on his own experience, even in cases where the logic of a formula escaped his understanding. Admittedly, the scattered narratives in Sun’s work are modest in scale compared to later compilations that are devoted to medical cases. Yet as the first formula book that incorporates such cases in Chinese history, the text exhibits the fledgling consciousness of using practice-based knowledge to validate therapeutic efficacy.

To appreciate this new feature of Chinese medical writing, it is necessary to position Sun’s text in the evolution of two medical genres, both with a practical bent. The first are formula books (fangshu), which already emerged in antiquity and remained a thriving genre throughout imperial China and beyond. The second are medical cases (yi’an), which appeared sporadically in early sources and only started to blossom as an independent genre beginning in the sixteenth century. Intriguingly, medical cases (observatio) in Europe also proliferated at the same time, leading to the rise of a new “epistemic genre,” a concept developed by the historian of medicine Gianna Pomata, which reveals distinct cognitive processes of generating empirical knowledge based on direct observation and firsthand experience.⁸² This comparative insight illuminates the reading of Sun’s Essential Formulas. Different from commentary texts such as materia medica, which faithfully copy the structure and content of the ancient classics, formula books are more eclectic, flexible, and open, incorporating remedies from diverse sources and of disparate social origins. Sun’s innovation of inserting medical cases into his collection of formulas, which resembles texts of experimenta that appeared in late medieval Europe, adds further weight to the practical orientation of the genre.⁸³ Using these examples to showcase the efficacy of his formulas, Sun promotes a new mode of knowledge production that is rooted in personal experience.⁸⁴

Finally, it is important to point out that within the genre of formula books, different texts reveal subtle epistemic differences. The eighth-century Arcane Essentials from the Imperial Library, for instance, also contains a massive number of formulas. Yet unlike Essential Formulas, the text specifies the source of each of its six-thousand-odd prescriptions, many of which were copied from Sun’s writing, and includes no accounts of the author’s own experience. Revealingly, Wang Tao, the author of the book, was a scholar-official who had keen interest in medicine but probably did not engage in medical practice beyond self-healing. As the title indicates, he compiled the formula book based on a thorough survey of medical works in the imperial library, which is in contrast to Sun’s emphasis on the practical use of his remedies to treat emergencies.⁸⁵ Hence the ways that scholar-officials produced medical knowledge and wrote about their experiences (or lack thereof) were related to but distinct from those of physicians like Sun. The two groups frequently exchanged knowledge of healing and sometimes debated the proper use of certain formulas. The dynamic interplay was broadcast in their heated discussion on one of the most controversial drugs in medieval China, Five-Stone Powder, the subject of the next chapter.