Shennong Bencao Jing: The Divine Farmer's Materia Medica (神农本草经)

Historical Context: The Earliest Pharmacological Text

The Shennong Bencao Jing (神农本草经), whose title translates to "Divine Farmer's Materia Medica," holds a unique position in the history of Chinese medicine as the earliest known systematic pharmacological text. Compiled during the Han dynasty (approximately 200 BCE to 200 CE), it represents the culmination of centuries of accumulated herbal knowledge, systematized into a coherent text that would shape Chinese pharmacology for the next two thousand years.

The text is attributed to Shennong (神农, the Divine Farmer), a legendary figure in Chinese cultural history. According to tradition, Shennong was one of the mythological sovereigns of ancient China, credited with inventing agriculture, introducing the plow, and — most relevant to this text — tasting hundreds of herbs to determine their medicinal properties. The legend holds that Shennong had a transparent stomach through which he could observe the effects of herbs on his internal organs, and that he tasted as many as seventy poisons in a single day, using tea as an antidote. While this is clearly mythological, the story reflects something important about the empirical foundation of Chinese pharmacology: the knowledge of herbs was gained through direct experience, observation, and sometimes considerable personal risk.

In reality, the text was most likely compiled by anonymous physicians and scholars during the Western and Eastern Han dynasties, drawing on oral traditions and earlier written records that have since been lost. The attribution to Shennong was a common practice in ancient China — lending the authority of a revered cultural figure to a text to enhance its credibility. This practice was not deceptive in the ancient context but rather reflected the belief that accumulated knowledge belonged to the cultural tradition as a whole, personified by its legendary founders.

The original text was lost over the centuries, like many ancient Chinese works. It survived through quotations in later medical texts and was reconstructed during the Qing dynasty by scholars who painstakingly compiled the surviving fragments. The most important reconstruction was undertaken by Sun Xingyan (孙星衍) and Sun Fengyi (孙冯翼) in 1799, and another by Gu Guanguang (顾观光) in 1844. These reconstructions, based on quotations from the Tang dynasty Xinxiu Bencao and other sources, provide the version of the text that scholars study today.

The Three Grades System: Classification of 365 Herbs

The most significant contribution of the Shennong Bencao Jing is its Three Grades (san pin, 三品) classification system. The text describes 365 medicinal substances — a number deliberately chosen to correspond to the 365 days of the year, symbolizing completeness and cosmic harmony. These substances are divided into three grades, each reflecting a different therapeutic purpose and level of safety.

Upper Grade (上品, Shang Pin) — 120 Herbs

The upper grade contains 120 herbs that are considered non-toxic, nourishing, and suitable for long-term use. These are the herbs that strengthen the body's constitution, tonify qi, blood, yin, and yang, and promote longevity. The text states that upper-grade herbs are "for nurturing life" and "correspond to heaven" — reflecting the association of the upper grade with the celestial and the nourishing.

Many of the most famous tonifying herbs in Chinese medicine are classified as upper grade. Ginseng (Ren Shen), classified as upper grade, is described as tonifying the five organs, calming the spirit, and improving longevity. Licorice (Gan Cao), also upper grade, is noted for its ability to harmonize and detoxify. Rehmannia (Di Huang), the foundational yin-nourishing herb, is upper grade. Astragalus (Huang Qi), the premier qi tonic, is upper grade. The placement of these herbs in the upper category reflects the ancient understanding that substances which nourish and strengthen the body are fundamentally safe and beneficial when used appropriately.

The upper grade concept has profound implications for TCM practice. It establishes the principle that some herbs are not merely medicines for treating disease but are agents for enhancing health, preventing illness, and extending life. This concept — that medicine and nutrition exist on a continuum, with some substances serving both roles — is a distinctive feature of Chinese medical thought that continues to influence modern practice in the form of herbal dietary therapy and tonic herbalism.

Middle Grade (中品, Zhong Pin) — 120 Herbs

The middle grade contains 120 herbs that may have mild toxicity and serve a dual purpose: they can be used to treat illness while also supporting health. The text describes middle-grade herbs as "for nurturing nature" and "corresponding to humanity." These herbs occupy a middle ground — they are stronger than upper-grade herbs and can actively treat disease, but they are not so toxic that they cannot be used with reasonable safety.

Middle-grade herbs include many substances that are both therapeutic and potentially harmful if misused. Angelica (Dang Gui), the primary blood-tonifying herb, is classified as middle grade — reflecting its active, moving properties that make it therapeutic but require care in certain conditions (such as pregnancy). Peony (Bai Shao), which nourishes blood and softens the liver, is also middle grade. Some herbs in this category have both tonifying and draining properties, making them versatile but requiring skilled application.

The middle grade reflects the recognition that many useful therapeutic herbs occupy a gray zone between purely nourishing and purely disease-fighting. These herbs can strengthen the body while also addressing pathology, but their dual nature means they require more careful application than the safer upper-grade herbs.

Lower Grade (下品, Xia Pin) — 125 Herbs

The lower grade contains 125 herbs that are often toxic, used specifically to treat disease, and not intended for extended use. The text describes lower-grade herbs as "for treating disease" and "corresponding to earth." These are the most powerful and potentially dangerous substances in the pharmacopoeia — they can expel pathogens, drain accumulations, and resolve severe conditions, but they can also harm the body's healthy qi if used improperly or for too long.

Lower-grade herbs include many substances that are strongly purgative, emetic, or externally applied for skin conditions. Rhubarb (Da Huang), a powerful purgative that drains heat and accumulations through the bowels, is classified as lower grade. Many mineral and animal substances, which tend to be more toxic than plant materials, are also found in this category. The classification of these substances as lower grade serves as a clear warning: they are medicines for specific, acute conditions, not tonics for general use.

The lower grade concept embodies a crucial safety principle that remains relevant today: powerful medicines that fight disease are inherently more dangerous than gentle, nourishing substances, and their use must be time-limited and carefully supervised. This principle — that stronger medicine carries greater risk — is a foundational concept in TCM pharmacology that the Three Grades system makes explicit.

Classification Principles Beyond the Three Grades

While the Three Grades system is the most famous aspect of the Shennong Bencao Jing, the text also established several other classification principles that became foundational to Chinese pharmacology.

Herb properties (natures and flavors). Each herb is described in terms of its nature (cold, cool, warm, hot, or neutral) and its flavor (sour, bitter, sweet, pungent, or salty). These properties determine the herb's therapeutic effects: cold-natured herbs clear heat, warm-natured herbs dispel cold, sweet herbs tonify and harmonize, bitter herbs drain and dry, pungent herbs disperse and move, sour herbs astringe and contain, and salty herbs soften and purge. This framework — classifying herbs by their energetic properties rather than by their chemical composition — is one of the most distinctive features of Chinese pharmacology and remains the basis of herbal classification today.

Channel affinity (gui jing). The text notes that specific herbs have affinities for specific organ systems. An herb may enter the lung channel, the liver channel, or the kidney channel, determining where its primary effects are felt. This concept allows practitioners to direct the effects of an herb to a specific organ or region, making herbal prescriptions more targeted and effective. The idea of channel affinity was more fully developed in later texts but has its roots in the Shennong Bencao Jing's descriptions of where each herb acts.

Toxicity awareness. The Three Grades system itself is fundamentally a toxicity management framework. The text explicitly notes which herbs are toxic, which are non-toxic, and which can be used long-term. This early attention to herbal toxicity — recognizing that even natural substances can be harmful — demonstrates the practical, safety-conscious nature of ancient Chinese pharmacology. The text also describes methods for processing herbs to reduce toxicity, a practice that evolved into the sophisticated pao zhi (processing) techniques used in modern TCM.

Key Herbs and Their Properties

Many of the herbs first systematically described in the Shennong Bencao Jing remain among the most important in modern Chinese medicine. Below are several representative herbs from the text, each illustrating the classification principles.

Ren Shen (人参, Ginseng) — Upper Grade

• Properties: Sweet, slightly bitter, slightly warm
• Actions described in the text: Tonifies the five organs, calms the spirit, settles the soul, stops fright, eliminates evil qi, brightens the eyes, opens the heart, and benefits wisdom. Used long-term, it lightens the body and extends life.
• Modern significance: Ginseng remains one of the most valued herbs in Chinese medicine, used for severe qi deficiency, recovery from illness, and as a general tonic. The Shennong Bencao Jing's description of its multifaceted benefits — physical, mental, and spiritual — captures the holistic understanding that TCM brings to herbal therapy. Modern research has confirmed ginseng's adaptogenic, immune-modulating, and cognitive-enhancing properties.

Gan Cao (甘草, Licorice Root) — Upper Grade

• Properties: Sweet, neutral
• Actions described in the text: Tonifies the five organs, nourishes the spleen, moistens the lungs, relieves spasms, and detoxifies. Used long-term, it lightens the body and extends life.
• Modern significance: Licorice is perhaps the most frequently used herb in Chinese medicine — it appears in more than half of all classical formulas. Its ability to harmonize the actions of other herbs, reduce toxicity, and moderate the effects of harsher ingredients makes it indispensable. The Shennong Bencao Jing's recognition of its detoxifying properties is particularly noteworthy, as licorice is still used as an antidote for various poisonings in TCM.

Da Huang (大黄, Rhubarb Root) — Lower Grade

• Properties: Bitter, cold
• Actions described in the text: Drains accumulation, pushes out stagnation, clears heat, purges fire, moves blood, and resolves swelling. Should not be used long-term.
• Modern significance: Rhubarb is one of the most important purgative herbs in TCM, used for constipation with heat, abdominal fullness, and various conditions requiring the drainage of heat and accumulations through the bowels. Its classification as lower grade is entirely appropriate — it is a powerful medicine for specific conditions, not a general tonic. The text's warning against long-term use reflects the understanding that powerful purgatives can damage the spleen and deplete qi if overused.

Gui Zhi (桂枝, Cinnamon Twig) — Upper Grade

• Properties: Pungent, sweet, warm
• Actions described in the text: Releases the exterior, warms the channels, facilitates the flow of qi and blood, and promotes sweating.
• Modern significance: Cinnamon twig is one of the most frequently used herbs in classical formulas, appearing prominently in the Shanghan Lun as the sovereign herb in Gui Zhi Tang (Cinnamon Twig Decoction). Its classification as upper grade reflects its relatively safe, warming, and harmonizing nature. Modern research has confirmed its circulatory, anti-inflammatory, and antimicrobial properties.

Influence on Later Bencao Literature

The Shennong Bencao Jing did not exist in isolation — it became the foundation upon which an entire tradition of Chinese pharmacological literature was built. Over the centuries, successive scholars expanded, revised, and systematized the original text, producing increasingly comprehensive materia medica works.

The first major expansion came with the Mingyi Bielu (Supplementary Records of Famous Physicians) by Tao Hongjing (陶弘景, 456–536 CE) in the Liang dynasty. Tao added 365 new herbs to the original 365, bringing the total to 730, and reorganized the text with additional commentary on each herb's properties. He also grouped herbs by natural categories (plants, animals, minerals) within each grade, adding a second level of organization.

In the Tang dynasty (618–907 CE), the imperial government commissioned the Xinxiu Bencao (Newly Revised Materia Medica, 659 CE), which expanded the herb count further and was the first pharmacopoeia in the world to be sponsored by a national government. In the Song dynasty, the Zhenglei Bencao (Classified Materia Medica, 1082 CE) became the authoritative reference, incorporating all previous work and adding extensive commentary.

The culmination of this tradition came with Li Shizhen's Bencao Gangmu (Compendium of Materia Medica, 1578 CE), which cataloged 1,892 substances in 52 volumes. Li Shizhen explicitly acknowledged his debt to the Shennong Bencao Jing, and his work can be seen as the ultimate flowering of the tradition that the earlier text had established. Yet even in this vastly expanded work, the principles of the Shennong Bencao Jing — classification by nature and flavor, attention to toxicity, and the distinction between nourishing and disease-fighting herbs — remained the organizing framework.

The Shennong Bencao Jing also influenced medical practice beyond pharmacology. Zhang Zhongjing, in his preface to the Shanghan Zabing Lun, explicitly cited the Shennong Bencao Jing as one of the texts he studied. The formula compositions in the Shanghan Lun and Jingui Yaoluee reflect the herb property descriptions first systematized in the Shennong Bencao Jing — the pairing of herbs based on their natures and flavors, the attention to channel affinity, and the careful management of toxicity all derive from the pharmacological framework established in this foundational text.

Relationship to Modern Chinese Herbal Medicine

The Shennong Bencao Jing's influence extends directly into modern TCM practice. The herbs it cataloged, the properties it assigned to them, and the safety principles it established continue to guide contemporary herbal medicine.

The herb properties described in the text — natures (cold, hot, warm, cool) and flavors (sweet, sour, bitter, pungent, salty) — remain the primary system for classifying and understanding herbs in modern TCM education and practice. When a modern practitioner describes an herb as "sweet and warm, entering the spleen and lung channels," they are using a classification system that traces directly back to the Shennong Bencao Jing. This continuity across two millennia is one of the most remarkable aspects of Chinese medicine.

The Three Grades system, while no longer the primary classification method in modern TCM (which organizes herbs by function — tonifying, heat-clearing, exterior-releasing, etc.), continues to influence clinical reasoning. The concept that some herbs are safe for long-term use while others should be used only briefly remains a fundamental safety principle. Modern TCM education still teaches students which herbs are appropriate for extended use (typically tonics) and which must be time-limited (typically purgatives, herbs with toxicity, and strong dispersing herbs).

Many of the individual herbs first documented in the text are now the subject of extensive pharmacological research. Ginseng (Ren Shen), licorice (Gan Cao), cinnamon (Gui Zhi and Rou Gui), rehmannia (Di Huang), and astragalus (Huang Qi) — all upper-grade herbs in the Shennong Bencao Jing — are among the most researched Chinese herbs in modern scientific literature. Studies have confirmed many of the properties described in the ancient text: ginseng's adaptogenic and immune effects, licorice's anti-inflammatory and detoxifying properties, astragalus' immune-enhancing actions, and rehmannia's effects on blood and kidney function.

This convergence between ancient observation and modern science is one of the most compelling aspects of Chinese herbal medicine. The physicians who compiled the Shennong Bencao Jing, working without modern analytical tools, identified the therapeutic properties of these herbs through careful observation and systematic documentation — properties that modern pharmacology continues to validate. The text stands as a testament to the power of empirical medicine and the enduring value of systematic clinical observation.