The Etymology of Du

To appreciate the significance of du in classical Chinese pharmacy, it is necessary to trace the meanings of the word in the broader cultural context of early China. An informative entry point is the Han text Explaining Simple and Analyzing Compound Characters (Shuowen jiezi, 100; hereafter, Explaining Characters), the first comprehensive dictionary in China. Compiled by Xu Shen (ca. 55–ca. 149), the text manifests the Han scholar’s effort to systematize written language based on the ancient meanings of characters. Although the dictionary by no means preserves the “original” sense of du, it offers useful glosses that reveal the multivalent interpretation of the word.³ Fundamentally, du is defined as “thickness” (hou), which in turn is explained as “thickness of lofty mountains.”⁴ Du and hou share similar features: heavy, dense, and abundant. Neither of the words bears a negative connotation.⁵

Explaining Characters offers a second, less innocuous meaning of du. Du is compared with a harmful grass that grows invasively, everywhere. A sense of “thickness” is still implied here—the poisonous plant is rampant, wanton, and unrestrained. Luxuriant growth insinuates latent danger. To support this idea, the dictionary partitions the character into two parts: the top part cao 屮, which means “grass,” and the bottom part ai 毐, which means “unvirtuous person” (figure 1.1a). Altogether, du denotes an undesirable herb that engenders harm.⁶

Du was not one idea, nor was it written with one character. In addition to the foregoing meanings, there was yet another entirely different graph for du that dates to the pre-Han era (figure 1.1b). Explaining Characters describes it as an ancient form of du that consists of two parts: dao 刀 in the lower-right corner, which means “knife,” along with fu 葍, which designates an invasive plant, anticipating the interpretation of du as wild and pernicious grass during the Han period.⁷ What is the relationship between the knife and the grass? It has been suggested that because the character fu, which is phonetically related to hou (thickness), intimates a swelling or ulcer on the body, one could use a knife to cut it away.⁸ Although du is implicated in treating ulcers in ancient sources, there is no evidence that it directly involved surgery. Instead, the composition of the character for du, consisting of the component parts “knife” and “grass,” can be interpreted literally: du is a knife smeared with the juice of a toxic plant, a deadly weapon for use in hunting or warfare. This was probably an important application of poisons in antiquity, if not earlier.⁹

Although Explaining Characters is an important source regarding etymology, its interpretations of du were conditioned by Xu Shen’s intellectual agenda and political ambition.¹⁰ Can we retrieve other meanings of du beyond the Han text? A clue comes from an obscure variant of the word preserved in the sixth-century dictionary Jade Chapters (Yupian) (figure 1.1c).¹¹ This character is derived from an oracle bone script written as in figure 1.1d. Intriguingly, these graphs link du to animals: the upper part symbolizes a foot and the lower part a snake; the combination of the two indicates a person stepping on a venomous animal. An ancient meaning of du, therefore, pointed to threats posed by dangerous creatures in nature.¹²

In sum, there are at least three different meanings of du in ancient China, based on etymological analysis. Before the Han dynasty, the word could refer to a weapon made from poisons or the danger of a pernicious animal. The positive sense of the word is absent in these early graphs. Yet during the Han period, the word acquired the meaning of “thickness,” which implies heaviness, intensity, and unconstrained growth. The negative sense of the word still persisted, but this new gloss suggests a changed conception of du, whose meaning became more ambivalent. In addition, du is explicitly tied to herbs in Explaining Characters, indicating the rapid expansion of herbal knowledge at the time. Revealingly, yao, the character for drug, also contains the radical for “grass” (cao 艸). The meaning of this word, according to the Han dictionary, is “grass that cures illness.”¹³ As classical Chinese pharmacy by no means contained only herbs, the focus on grass in the definition of yao further suggests the growth of herbal medicine during the Han period.

The Meanings of Du in Early Chinese Sources

The curious etymological history of du offers preliminary insights into its rich meanings. We can bring more focus to the complexity of the word with other types of sources to see how its meanings are expressed in specific contexts. One of the earliest mentions of du in Chinese history comes from The Classic of Changes (Yijing or I Ching, also known as Zhouyi), a divination text the core of which was formed around the end of the second millennium BCE.¹⁴ The book establishes a spatiotemporal cosmological system manifested by sixty-four hexagrams, each of which is linked to a particular scenario and a prophetic message. In a section called “Gnawing and Chewing” (Shike), the text relates that when one gnaws dry meat and encounters poison (du), this causes minor distress but no real troubles.¹⁵ Du in this situation carries a negative meaning, much like food poisoning to the modern reader. Poisoning by the corruption of food has been suggested as the original meaning of du based on the similarity of the ancient pronunciations of du and shu, which means “ripe.”¹⁶ This type of poisoning is, nonetheless, only perceived as a minor annoyance in the text, not a sign of significant danger.

In another passage, du invokes an entirely different meaning. Rather than referring to a vexing matter, it designates a political force: “Remain sturdy at the center to respond to all situations; stay adaptive upon encountering dangers. If a king can rely on these qualities to govern [du] the world, people will follow him. Being propitious, how is it possible to cause troubles?”¹⁷ Du in this passage can be read as an action performed by a capable ruler. If a leader acts sagaciously, he can rule his people with success. Du thus implies the abundance of virtues and the consolidation of capacities. Such virtues and capacities empower the king to achieve effective governance. Here, in one of the earliest books in China, we see two distinct expressions of du.¹⁸

The positive sense of du also appears in ancient philosophical texts. For instance, a passage in the foundational Daoist work Laozi (ca. fourth century BCE) elucidates the profound importance of the Dao and virtue: “Therefore the Dao creates all things, and virtue raises them—cultivates them and fosters them, rears them and nurtures [du] them, nourishes them and protects them.”¹⁹ The sentence uses a series of synonymous words, including du, to describe the power of virtue (de), which facilitates the growth of all things in the world. Du embodies the unfolding of the cosmos.

What, then, does du mean in the medical context? The key term to examine is duyao, which stands for “poison” in modern contexts but had quite different meanings in antiquity. The important text in this respect is Rites of Zhou (Zhouli, ca. third century BCE), which presents an idealized structure of the royal bureaucracy in preimperial China.²⁰ Among the 360-odd offices listed in the book, five are designated for medicine: one for the general supervision of medical affairs and four specialists on preparing foods and treating internal disorders, lesions, and animal maladies. The text defines the duty of the first type of officer, called “master of physicians” (yishi), as taking charge of medical policies and orders, as well as collecting substances referred to as duyao to supply the practices of physicians.²¹ In this early usage, it appears that the word duyao, composed of two characters, as are many words in Chinese, referred to two different types of drugs: potent ones (du) and mild ones (yao). The composite, then, became a term for drugs in general.

This interpretation is supported by another passage in the text that explains the responsibilities of physicians who specialize in treating lesions. They use “five potent drugs [du] to attack them, five qi to nourish them, five mild drugs [yao] to heal them, and five foods to restrain them.”²² Placed in distinct categories, du and yao are both important for treating lesions. The former, associated with the act of “attack” (gong), bears a strong sense of intensity and forcefulness. The latter, associated with the act of “healing” (liao), probably refers to drugs of lesser power. In the passage that immediately follows, the text further specifies that these mild drugs are used to nourish (yang) different parts of the body, suggesting their tonic value.²³ Among the four types of specialists, only physicians who treat lesions employ du, which indicates the emphasis on the topical use of powerful drugs in ancient China.²⁴ The identity of the exact drugs, however, remains elusive.

The term duyao changed its meaning in Han medical sources. Two different usages can be detected in the Han-era The Yellow Emperor’s Inner Classic (Huangdi neijing), a foundational text in Chinese medical history that served later readers as a crystallization of the basic theories of medicine in antiquity. The first usage there is consistent with the definition in Rites of Zhou in the sense that duyao refers to both potent and mild drugs. Yet a significant change is that rather than being applied topically, potent drugs were employed, together with mild drugs, to eliminate illness inside the body. Exterior conditions were instead treated by needles and stones.²⁵ The second usage of the term in The Yellow Emperor’s Inner Classic is more restrictive, namely, that duyao refers only to potent drugs. In a case where the text explains the options for treatment, it lists five in particular, each with a distinct function: “The potent drugs [duyao] attack the devious; the five grains provide nourishment; the five fruits provide support; the five livestock provide enrichment; the five vegetables provide replenishment.”²⁶ The verb “attack” resonates with language found in Rites of Zhou, indicating the power of the drugs. They contrast with other types of healing that are milder and slower, aiming to nourish the body. This second meaning of duyao gradually superseded the first, more inclusive sense of the term in Chinese medical writings from the Han period onward.

Moreover, this second sense of duyao has implications beyond the medical context: in the story that opens this chapter, its effects were compared with those of powerful words. The link between du and speech is particularly evident in Discourses Weighed in the Balance (Lunheng, first century), a collection of essays on history, philosophy, and natural science compiled by the Han scholar Wang Chong. In a chapter titled “Speaking of Poison,” Wang associates all potent things with the heat, fire, and qi of yang, as perceived in the yin-yang framework.²⁷ That is, the hot, vehement qi in southern regions not only causes the thriving of poisonous plants and animals but also endows local people with a unique capacity to utter especially mighty words. Intriguingly, he uses this theory to explain the shamanistic practices prevalent in the south that often employed incantations to heal or kill. This more expansive interpretation of du unified words and things under the scheme of a sultry qi, reflecting a southern attitude that was of a piece with the local environment.²⁸

Du in the First Chinese Materia Medica

How has the ambivalence of du manifested itself in Chinese pharmacy? The question directs us to the first pharmacological treatise in China, The Divine Farmer’s Classic of Materia Medica (Shennong bencao jing, ca. first century; hereafter, The Divine Farmer’s Classic). The title of this foundational text merits scrutiny. The term bencao, which first appeared during the Han period, refers to knowledge about drugs and the genre producing such knowledge. In the same way that the English word “root” is used metaphorically, bencao literally means either “rooted in grass” or “roots and grass,” indicating the prominence of herbal medicine in the Han pharmacy.²⁹ Bencao texts in China resemble a type of European pharmacological writing, often called materia medica, that can be traced back to the foundational work De Materia Medica by the Greek physician Dioscorides in the first century.³⁰ Both genres provide a list of drugs, each with an account of the properties, habitats, appearance, and medical uses of the substance. Because of this textual similarity, I translate bencao as “materia medica.”

But who was “the Divine Farmer” (Shennong)? As the putative author of the book, he was a mythical leader who, at the dawn of civilization, developed agriculture to benefit his people. He was also credited for discovering useful medicines, which won him the reputation as the founder of drug therapy in China. According to an early Han source, the brave man tasted hundreds of herbs to identify suitable medicines for his followers, and encountered seventy potent substances each day. The tale indicates that daily experience and trial-and-error effort played an important role in the accumulation of drug knowledge in early China.³¹ The medical identity of the Divine Farmer was firmly established during the Han dynasty; sources at the time considered him, along with several other esteemed figures, such as the Yellow Emperor and Lord Thunder, to be a sage who lived in high antiquity and possessed the true, pristine knowledge of medicine. The attribution of a text to the sage thus suggests the recovery of lost pharmacological wisdom from a glorious past.³²

The actual author(s) of The Divine Farmer’s Classic, however, is unknown. It was possibly compiled by a group of Han officials who specialized in drugs. Known as “materia medica specialists awaiting edicts” (bencao daizhao), they were summoned by the court when their skills were in demand and dismissed when they were no longer needed. Both knowledgeable and disposable, these specialists are often juxtaposed in Han sources with men of “methods and arts” (fangshu), a term that encompasses a wide range of magical and esoteric techniques, such as astrology, geomancy, alchemy, and divination, among others. Possibly, the materia medica specialists exchanged knowledge with these technical adepts, who influenced the former group’s understanding of drugs.³³

The Divine Farmer’s Classic, the first systematic writing on drugs in China, was foundational to the theory and practice of Chinese pharmacology. All later materia medica texts adhered to its basic framework of categorizing and defining drugs, and relied on its empirical knowledge to guide medical practice.³⁴ We know little about the formation of the text and the origins of its sources except that the work was probably a consolidation of drug knowledge accumulated in the preceding centuries. The evidence mainly comes from the medical manuscripts excavated from Han tombs, of which two sets are particularly revealing. The first is an assembly of medical formulas discovered from the tomb of a local lord in Mawangdui (in present-day Hunan, ca. 168 BCE). This collection of silk manuscripts contains close to three hundred formulas that treat fifty-two types of disorders. Based on a conservative estimate, more than two hundred drugs of plant, mineral, and animal origins are deployed, either internally or topically, in this miscellany of remedies. Among them, seventy-odd substances also appear in The Divine Farmer’s Classic, indicating a process of crystalizing drug knowledge out of formula books during the Han period.³⁵

The second set of manuscripts suggests a different route to the formation of the Han pharmacopoeia. Unearthed from a local nobleman’s tomb in Shuanggudui (in present-day Anhui, ca. 165 BCE), this collection of bamboo slips carries a list of more than one hundred drugs, each aiming to treat a medical condition or elicit a magical effect, such as running with high speed and lightening the body, the latter entailing the transformation of the body to higher states of being. Given the term “ten thousand things” (wanwu) that appears at the beginning of the slips, the collection offers a type of natural history that seeks to identify the possible uses of all things under heaven.³⁶ Thus the scope of the work goes beyond healing, describing other uses of things in hunting and fishing, clothes-making, and producing fuels, among others. The slips are just fragments containing miscellaneous information, yet they represent the earliest evidence of a nascent materia medica that embeds drug knowledge within the broader discussion of natural history.³⁷

Before investigating the content of The Divine Farmer’s Classic, it is necessary to position it in the broader Han culture of medical compilation. All medical texts from the Han period have been lost to us; fragments of manuscripts found in excavations, including the two sets mentioned above, are the only sources directly available from the period. Yet The History of the Han (Hanshu, first century) preserves an extensive bibliography from the imperial library—the earliest in Chinese history—that lists the titles of close to six hundred families of books organized into distinct categories. The construction of the bibliography was driven by a movement that took place in the last years of the Western Han dynasty, when several imperial scholars systematically collected and organized classic and contemporary works to reestablish textual authority to guide sage governance.³⁸ Titles on healing are presented at the end of the list, in a section on “methods and techniques” (fangji), which is further divided into four subsections: medical classics (yijing), classical formulas (jingfang), arts of the bedchamber (fangzhong), and arts of transcendence (shenxian).³⁹ The second subsection is particularly relevant to pharmaceutical knowledge. Although all eleven titles in this subsection are those of formula books, they relied on the knowledge of individual drugs to offer effective prescriptions. Given that no materia medica titles appear in the bibliography, such drug knowledge was probably still sporadic and unorganized during this period, embedded in formula books and works on natural history, only becoming systematized in the independent genre of bencao in the Eastern Han period.

Now let’s take a close look at The Divine Farmer’s Classic.⁴⁰ The book contains a short preface that introduces its organization scheme and the basic principles of drug therapy. The main body of the work characterizes a total of 365 drugs corresponding to the number of days in a year, demonstrating the cosmological framework grounding this early pharmacopoeia. Significantly, the book parses these drugs into three categories. The opening of the text defines these categories as follows:

The higher-level drugs of 120 kinds are the lords. They govern the cultivation of life and correspond to heaven. They do not possess du. Taking them in large amounts or for long periods does not harm people. Those who wish to lighten the body and enhance qi, prevent aging, and prolong life should rely on the higher-level drugs in [The Divine Farmer’s] Classic.

The middle-level drugs of 120 kinds are the ministers. They govern the cultivation of the human nature and correspond to man. Some of them do not possess du; others do. One needs to gauge carefully the proper use of them. Those who wish to prevent illnesses and replenish the weak body should rely on the middle-level drugs in [The Divine Farmer’s] Classic.

The lower-level drugs of 125 kinds are the assistants and envoys. They govern the curing of illnesses and correspond to earth. Most of them possess du. One may not take them for long periods. Those who wish to eliminate cold, heat, and devious qi; to break stagnations; and to cure illnesses should rely on the lower-level drugs in [The Divine Farmer’s] Classic. [Emphases added.]⁴¹

The passage reveals two key features of classical Chinese pharmacology. First, drugs are divided into three groups, and du stands out as the defining characteristic for each category. This du-centered classification of drugs would remain fundamental to Chinese pharmacy throughout the premodern era. Second, du figures not as something to be avoided at all costs but as potency valuable for curing illness. Precisely because of this perceived therapeutic power, drugs in the bottom group, most of which possess du, are deployed to treat a variety of disorders. The ambivalence of du is manifest in The Divine Farmer’s Classic: since it could evoke both benefit and danger, one should resort to a potent drug only for short periods, use it with caution, and stop using it once the illness was eliminated. A du-possessing drug, the text implies, cures if used properly and harms if it is not.

Although potent drugs are useful therapeutic substances, The Divine Farmer’s Classic places most of them at the bottom of the hierarchy and regards them as inferior to those in the middle and top groups. Rather than treating illnesses, drugs in the middle category serve to strengthen the body in order to prevent it from falling sick. This goal aligns well with a medical philosophy that was developing during the Han dynasty, captured in an aphorism from The Yellow Emperor’s Inner Classic: “The sage only treats people who are not yet sick, not people who are already sick.”⁴² It is always better to prevent maladies from occurring than to treat them after they arise.

Moreover, drugs in the top group, which do not possess du, are intended for an even higher goal: to prevent aging and prolong life, an aspiration that resonates with the ideal of “nourishing life” (yangsheng) in China. This ancient tradition proposes the regular ingestion of tonic substances, such as mushrooms, resin, and minerals like mica, combined with bodily movement, breathing, and meditation techniques in order to achieve longevity.⁴³ These methods aim to replenish qi and eliminate internal poisons that cause bodily decay. Drugs without du thus “lighten the body” and purify it of its toxic burdens. Meanwhile, drugs that possess du, with their characteristic “thickness,” invigorate the body in order to combat maladies. A potent substance effectively cures sickness but impedes one from achieving a loftier goal: the cultivation of a healthy, long life.⁴⁴

The main body of The Divine Farmer’s Classic describes 365 drugs in detail, which include minerals, plants, animal substances, and foods. For each drug, it specifies its flavor, its qi (degree of heat), the illnesses it treats, the benefits it brings to the body, the place of its harvest, and sometimes its alternative names. The first two, flavor and qi, warrant further explanation, as they were the basic categories used to define drug properties in classical Chinese pharmacy. Each drug is characterized by one of the following five flavors (wei): pungent, sweet, sour, bitter, or salty. These flavors do not necessarily match the sensations as we experience them today but rather are abstract concepts positioned in the five-phase system that correlates the flavor of a drug to a particular organ in the body: pungent drugs to the Lungs, sweet drugs to the Spleen, sour drugs to the Liver, bitter drugs to the Heart, and salty drugs to the Kidneys. Such correlations played an important role in guiding prescriptions.⁴⁵ Furthermore, the degree of heat, or qi, refers to the temperature of a drug that could be cooling, warming, or plain, as established in The Divine Farmer’s Classic. Each of these three properties is often an indicator of the corresponding bodily sensation induced by the drug; a warming drug, for example, generates heat in the body. This definition of qi, which speaks to the materiality of drugs, is related to but distinct from the meaning of qi as a vital force circulating in the body.

Despite the general outline of the du-centered organization in the preface, The Divine Farmer’s Classic does not specify the du status, namely, whether a drug possesses du or not, for each of its 365 drugs.⁴⁶ In the formative years of Chinese pharmacology, such knowledge may not have been systematically developed. It is not until the end of the fifth century, with the rise of an important commentary to the Han text, that an elaborate account of potent drugs emerged.

Potent Drugs in Collected Annotations

Collected Annotations on the Classic of Materia Medica (Bencao jing jizhu, ca. 500; hereafter, Collected Annotations) is a pivotal text in the history of Chinese pharmacology. Building on the Han classic, the work substantially expands drug knowledge by doubling the number of entries and adding more information about the appearance, source location, and medical uses of drugs. Importantly, it specifies the du status of most of its 730 drugs, and provides rich discussion of some oft-used du-possessing drugs in Chinese pharmacy. It also explains a variety of techniques for processing and deploying these substances. The text is thus an indispensable source for studying the conceptualization and uses of potent medicines in China.

Collected Annotations emerged at a time of political disunity in China. From the early fourth century to the late sixth century, various groups of nomadic peoples of Turkic, Mongolian, and Tibetan origin invaded the northern lands and pushed the Han people to the region south of the Yellow River, where the latter established a succession of short-lived dynasties. Despite the political turmoil, medicine thrived thanks to the rise of powerful clans devoted to medical practice and the flourishing of religious healing. Specifically, a number of aristocratic families emerged in the south that produced influential medical works. Unlike the Han period, when medical knowledge was chiefly transmitted between a master and his carefully selected disciples, this new era witnessed the ascendancy of hereditary medicine within prestigious elite clans.⁴⁷ Furthermore, the fast development of Buddhism and Daoism during this period substantially enriched the repertory of healing; religious devotees of diverse groups adopted drug therapy, incantations, and meditation techniques to cure patients and achieve self-transformation. In particular, the rise of Daoist alchemy in the southeast, with its rich material practice of manipulating powerful minerals, informed pharmaceutical writings at the time.⁴⁸

The author of Collected Annotations is Tao Hongjing (456–536), who grew up in the southeast, near Jiankang (present-day Nanjing), the capital of the Southern Dynasties. Raised in an aristocratic family, Tao was a polymath who, when still in his twenties, became famous for his accomplishments in literature and calligraphy. He was also versed in medicine, which resulted from both family influence and individual initiative. According to Tao’s own account, over many generations his family had devoted themselves to studying and practicing curative arts; Tao’s father and grandfather both had advanced knowledge of drugs. They relied on a particular formula book called The Formulary of Fan to treat thousands of people.⁴⁹ Although there is no evidence that Tao himself practiced medicine, his family’s active engagement in healing probably contributed to his medical learning. According to a seventh-century bibliography, Tao compiled eight medical texts, including materia medica, formula books, and alchemical treatises, all pointing to his broad knowledge of medicine.⁵⁰

At an early age, Tao also became interested in Daoist writings. The southeastern area where he lived was fertile ground for new Daoist movements that in the fifth century had great appeal to social elites. In 492, after serving for more than a decade as a minor official at the court of the Southern Qi (479–502), he decided to abandon his political career and retire to Maoshan, a range of mountains not far from the capital, where he dedicated himself to Daoist practices of meditation, alchemy, and the compilation of Daoist works. It was also during these years of seclusion that he completed Collected Annotations.

As the title indicates, Tao’s work is based on The Divine Farmer’s Classic, but with significant modifications of both the structure and content of the Han pharmacopoeia. The text starts with a lengthy preface in which Tao not only comments on the short preamble of the Han classic but also explains in detail the methods of drug preparation and enumerates drugs for treating major illnesses and countering different types of poisoning, and various ways they could be combined in formulas to treat particular conditions. The hermit makes his motive for compiling the pharmacological treatise clear at the beginning of the preface, observing that in the centuries following the emergence of The Divine Farmer’s Classic, a number of medical writers either edited the Han text or produced their own unique pharmaceutical works. These efforts often led to errors and confusions that led physicians astray. To rectify this chaos, Tao compiled his new materia medica based on a comprehensive study of all pharmaceutical works available to him. Collected Annotations thus reflects Tao’s effort to assemble and synthesize pharmaceutical knowledge that combined ancient wisdom with the new understanding of medicines during his time.⁵¹

There are altogether 730 drugs in Collected Annotations. Half of them (365) are copied from The Divine Farmer’s Classic and the other half from what Tao calls “supplements from eminent physicians,” which refers to new accounts on drugs produced by physicians between the Han period and Tao’s time.⁵² Each drug entry contains three elements. The first is the text from The Divine Farmer’s Classic, copied faithfully in large red characters. The second, written in large black characters, is from former writings on the drug by post-Han physicians. Importantly, this element specifies whether the drug possesses du or not. Although it is impossible to narrow down in which particular text this specification initially appeared, Tao’s work was the first to systematically incorporate this knowledge into writings on materia medica.⁵³ The third element is Tao’s own commentaries, written at the end of each entry in small black characters.

By creating this multipart format, Tao initiated a long tradition of commentary writing in Chinese pharmacology. Instead of modifying the Han classic, he preserved it and added information from other sources as well as his own remarks. To distinguish these three elements, he marked them off using different colors and text sizes. It is unclear what writing material Tao used to produce Collected Annotations since this text in its original form has long been lost. Although paper was invented during the Han dynasty (first century), it only became a regular medium for court writings in the fifth century, and its spread to other corners of society was probably even slower.⁵⁴ Hence the time when Tao completed Collected Annotations (ca. 500) was a transitional moment in the evolution of writing technologies in China as paper was gradually replacing the older materials of bamboo and wooden slips. Tao could have used either medium for his writings.

Although the original Collected Annotations no longer exists, there is a small fragment of a paper manuscript of the text dating to the seventh century, which offers us a concrete idea of what Tao’s text looked like (figure 1.2). The manuscript, discovered in the early twentieth century in the Turfan area (in present-day Xinjiang), might have been an official copy of the text from the Tang imperial library.⁵⁵ It includes the entries for four animal-derived drugs: hog’s testicle, swallow droppings, bat droppings, and mole’s meat. For each drug entry, excerpts from The Divine Farmer’s Classic are written in red (shown as light characters in figure 1.2), while the text in black (shown as dark characters in figure 1.2) is Tao’s additions (large characters) and commentaries (small characters). Significantly, the information of whether a drug possesses du or not is written in black, indicating that this knowledge was later added to the Han work.⁵⁶ This particular way of commentary writing persisted in the following centuries; later materia medica texts followed suit by adding new drugs and attaching still more layers of annotation to the existing drug entries. Owing to this format, even though complete works of materia medica from early periods such as The Divine Farmer’s Classic and Collected Annotations are lost to us, their content has been preserved in later sources, allowing for recovery.⁵⁷

In addition to designating the du status of each drug, Tao also made one significant change in the organizational scheme of his work. He had based his edition on a version of The Divine Farmer’s Classic that contained four scrolls, including a short preface and three content scrolls for drugs in the top, middle, and bottom groups, respectively.⁵⁸ Tao reorganized the text and created two new versions of his materia medica. The first has three scrolls, with the preface in the first scroll and about half of the 730 drugs in each of the remaining scrolls. The second version, called “the enlarged book” (dashu), is divided into seven scrolls: the preface, one scroll on mineral drugs, three on herbal drugs, one on animal-derived drugs, and one on drugs of fruits, vegetables, and grains, as well as drugs that have names but are not used anymore.⁵⁹ Although Tao did not invent the concept of grouping drugs by natural category—the idea can be traced back to the Han period—his work was the first in Chinese history to establish this scheme as the basic structure of a text of materia medica.⁶⁰

Besides altering the number of scrolls, Collected Annotations also doubles the number of drugs, from 365 to 730. Disregarding those that “have names but are not used anymore,” the rest of the drugs (575) are distributed across four natural categories, as shown in table 1.1.

Overall, plants occupy the largest portion in the collection; more than half of the drugs are in this category, indicating the prominence of herbal pharmacology in Tao’s days. They are followed by animal-derived products (20%), foods (14%), and minerals (12%). The drugs are spread across the three-tier hierarchy more or less evenly, with those in the bottom group being slightly more numerous.

TABLE 1.1. Distribution of drugs in Collected Annotations

Note: The counts are based on Tao, Bencao jing jizhu, 2-7.127–516.

How does du figure in Collected Annotations? Tao inherited the du-based organization of drugs from The Divine Farmer’s Classic and integrated the three-tier hierarchy into each of the four natural categories. Besides defining whether a drug possesses du or not, he also created finer distinctions with regard to potency: those possessing “little du” (xiaodu), those “possessing du” (youdu), and those possessing “great du” (dadu), indicating a more nuanced understanding of these substances during his time. The distribution of all the du-possessing drugs in Collected Annotations is shown in table 1.2.

Overall, about one-fifth (22%) of the 494 drugs in the book are defined as possessing du.⁶¹ Consistent with the definition of du in The Divine Farmer’s Classic, the majority of these drugs are in the bottom group (71%); only eight du-possessing substances (7%) are in the top group. Moreover, the distribution of the du-possessing drugs among the four natural categories is uneven. The plant category contains the largest number (56), meaning more than half of the du-possessing drugs are plants. Yet proportionately, the animal category has the highest percentage of potent drugs—almost a third (30%) of the animal-derived medicines possess du. These two categories comprise a great majority of the potent drugs (84%). By contrast, the category of foods contains the least number of drugs possessing du (8%), which is to be expected, since most of these substances were intended to be consumed regularly.

What are these potent drugs?⁶² The group of minerals contains ten du-possessing substances, including mercury, sulfur, and four kinds of arsenic compounds.⁶³ Curiously, most of these drugs are placed in the middle rather than the bottom tier of the hierarchy, which deviates from the du-based organizational scheme. It is revealing that besides curing specific illnesses, many of these minerals are assigned the power of promoting transcendence, the chief aspiration of Chinese alchemy (see chapter 7). It is probably this lofty promise that enhanced the value of these substances.

TABLE 1.2. Distribution of du-possessing drugs in Collected Annotations

The plant group contains a large number of potent drugs, most of which are in the bottom tier. Almost all drugs possessing great du are in this tier, among which the most salient example is aconite. Tao lists four kinds of aconite in his book and praises one of them in particular, called “attached offspring” (fuzi), as “the lord of the hundred drugs.”⁶⁴ This is not hyperbole, as aconite was one of the most frequently prescribed drugs in classical Chinese pharmacy.⁶⁵ It was also a lethal poison, frequently used in murder in premodern China. Hence proper preparation was the key to harnessing this powerful herb. Other examples of potent plants include “the bean from Ba” (badou, croton), the fruit of an evergreen tree growing in the southwest that works as a strong purgative; “the hooking of the throat” (gouwen, gelsemium), a poisonous vine from the south that could both kill and heal; “the half summer” (banxia, pinellia), the tuber of an herb that is harvested in the summer; and “the seed of derangement” (langdang zi, henbane), a hallucinogenic plant that could both induce and cure mania. Tao identifies a variety of uses for these drugs, such as warming the body, breaking stagnation, eliminating swelling, and facilitating movement.⁶⁶

The potent drugs in the animal-derived group are also diverse. Not surprisingly, snakes appear here; their gallbladders are particularly valued for healing.⁶⁷ Another important drug in this group is “ox yellow” (niuhuang), which refers to bovine bezoars (ox gallstones). Placed in the top tier and defined as possessing little du, the drug promises to quell frenzy and pacify the mind. The popularity of the medicine is attested to by its exorbitant price and the proliferation of ersatz products during Tao’s time.⁶⁸ The most mysterious item in the group is the feathers of a bird called zhen (zhenniao mao), which were believed to possess great du. These special feathers could effectively counter snake poison.⁶⁹ They were so poisonous that any alcohol into which they were dipped could kill a person instantly. In fact, alcohol laced with zhen feathers was so notorious that the word has become a synonym for poison, as used in the popular idiom “drinking zhen to quench thirst” (yin zhen zhi ke).⁷⁰ The identity of the bird, however, remains murky.⁷¹

Finally, the group of foods contains several important drugs that possess du. One of them is a type of cannabis called “hemp seed” (mafen). Placed in the top tier, the drug seeks to treat various kinds of exhaustions and injuries, eliminate cold qi, and dissipate pus. Consumed for a long time, it can lighten the body and illuminate the spirit. Yet excessive ingestion of the nutriment makes one “see demons and run crazily”—an indication of a strong disturbance of the mind.⁷² Another valuable du-possessing drug is alcohol (jiu). As a substance of great heating capacity, it is often used as a solvent to release the power of drugs. Similar to cannabis, it could also stir the mind, making one disoriented and confused, an effect that is familiar to many.⁷³

Conclusion

One of the defining concepts in classical Chinese pharmacy was du. In the formative years of Chinese medicine, the meanings of du were more complex than the negative sense of “poison” that is associated with the word today. An important gloss of the word that emerged during the Han period was “thickness,” which implied strength, heaviness, and abundance, a characteristic with wide-ranging implications. Early Chinese sources also invoke du with a variety of connotations, ranging from effective governance to the nurturing power of virtue, from potent medicines to deadly poisons. Du was also used metaphorically to refer to harsh but constructive words. Ultimately, the paradox of du lives in its entwined potentials of benefit and harm.

The paradox of du is patently expressed in the materia medica of early China. It carries a strong sense of potency that constitutes a medicine’s therapeutic power. The three-tier hierarchy established in The Divine Farmer’s Classic relies on du as a principal criterion to categorize drugs. Drugs possessing du are valuable for curing illness because of their potency yet could sicken or even kill, also because of their potency. The art of harnessing potent drugs is thus to forcefully eliminate illness without jeopardizing the vitality of life. Later materia medica texts during the Era of Division, exemplified by Tao Hongjing’s Collected Annotations, provide more detailed accounts of these powerful substances, which are spread across all the natural categories and are assigned diverse medical uses. By the sixth century, the crucial role of poisons in healing had been firmly established in classical Chinese pharmacy.

What are the possible cultural explanations for the rise of this therapeutic feature in China? The epigraph at the opening of this chapter gives us a clue. The passage, from a second-century BCE philosophical text, stresses the usefulness of aconite, an herb possessing plentiful du. This is, of course, medically valid information. Yet the ultimate message of the text is a political one: it uses aconite as a metaphor for emphasizing the value of diverse types of people in the world, which, if recognized by a capable ruler, can greatly benefit the kingdom.⁷⁴ Importantly, this all-embracing political vision is aligned with a cosmological view that constitutes the core of the text: the cosmos, originating from the omnipresent Dao, is differentiated into yin and yang complements, the combination of which creates myriad things in the world.⁷⁵ As a result, all substances contain both yin and yang forces, which are mutually transformative and in perpetual motion. This cosmology, which finds its roots in ancient philosophical writings such as Laozi and Zhuangzi, emphasizes the dialectical relationship among all things that defies stable categorization. In this milieu, it is not surprising that poison and medicine, on the pattern of the yin-yang dynamism, are not fixed into distinct, stable categories. They are, in fact, mutually constitutive.

Poisons, with their great healing potential, are, after all, dangerous materials, the misuse of which could result in dire consequences. Physicians in China were fully aware of this, and devised a variety of methods to prepare and deploy them to maximize their benefit and curtail their harm. The central idea underlying the poison-medicine paradox in China is transformation: no fixed distinctions exist; all things are subject to perpetual change. To harness poisons, therefore, one must grasp the techniques of judiciously transforming them into therapeutic agents.