The Shennong Bencao Jing — The Earliest Extant Classic of Chinese Materia Medica

With the development of medicine, people's demand for and understanding of medicinal substances grew continuously, and their exploration and practical application of drugs for treating disease likewise progressed. By the Eastern Han dynasty, China's earliest pharmacological monograph — the Shennong Bencao Jing (Divine Farmer's Classic of Materia Medica) — had appeared.

“Bencao” (materia medica, literally “roots and herbs”) is a synonym for Chinese medicinal substances. Although among medicinal materials there are also many of animal, mineral, and other origins, the overwhelming majority belong to the category of plants and herbs. Since the varieties of plants are numerous and they are convenient to gather, “bencao” has commonly been used to denote all Chinese medicinals. The authorship of this text can no longer be verified. The borrowing of the name “Shennong” employs, much like the Huangdi Neijing, the method of attribution to an ancient worthy. The Shennong Bencao Jing is the earliest monograph on materia medica. Its discussions on medicinal substances and pharmaceutical affairs (methods of collection, processing, and usage, etc.) remain, even today, a principal theoretical basis and operational standard for medical and pharmaceutical practitioners.

The Shennong Bencao Jing is abbreviated as the Bencao Jing or the Ben Jing. When recording medicinal substances, the text classifies them by their intended use into three grades — upper, middle, and lower. The upper grade comprises 120 types, which are mainly non-toxic substances used primarily for nourishment and supplementation; they can eliminate disease while also being suitable for long-term consumption to strengthen the body and prolong life. The middle grade comprises 120 types, which are generally non-toxic or slightly toxic; most possess the dual effects of tonification and disease elimination, but are not intended for prolonged administration. The lower grade comprises 125 types, mainly substances used for dispelling pathogenic factors; most are toxic or have fierce medicinal properties, readily subduing the body's zheng qi, and are generally used only until the disease is resolved — they must not be used in excessive dosage. The entire text records a total of 365 medicinal substances. This method of classification was also the most primitive system of drug classification. It facilitated the selection and use of substances for lightening the body, prolonging life, and health cultivation and wellness, while at the same time providing a range of safe and effective drugs for treating disease. However, this classification method does not clearly delineate medicinal properties or the characteristics of their principal indications, making it relatively inconvenient for medical practitioners to study and organize; it is now rarely used.

In addition, following the formula-composing principle of sovereign, minister, assistant, and envoy proposed by the Neijing, the Ben Jing likewise uses the example of courtly ranks — sovereign and minister — to illustrate the primary and secondary relationships among medicinals and the principles of their combination. The Ben Jing also provides exhaustive descriptions of the nature and flavor of drugs, pointing out that the four qi (cold, hot, warm, and cool) and the five flavors (sour, bitter, sweet, pungent, and salty) are the fundamental disposition of medicinal substances, and that drugs can be selected according to the differing properties of the disease — whether cold, hot, damp, or dry. Cold diseases are treated with hot drugs; hot diseases are treated with cold drugs; damp diseases require warm, drying products; dry diseases require cool, moistening agents. They are combined with one another, with reference to the generating and restraining relationships of the five elements. Only through thorough understanding of a drug's meridian entry, its directional tendency, its ascending and descending, floating and sinking properties can one select drugs, formulate prescriptions, and combine them in a manner appropriate to the clinical situation.

The interrelationships among drugs are also a crucial key to pharmacy. The principle of the “seven relations of compatibility” (qi qing he he) proposed by the Ben Jing has played an immense role in the practice of medication over several thousand years. Among drugs, some, when used together, mutually assist one another, producing even greater efficacy — some even exert effects several times stronger than when either is used alone. Some drugs, when they encounter one another, will cause one party to reduce the medicinal nature of the other, making it difficult for the latter to function. Some drugs can diminish the toxicity of another drug, and are often used in the processing of toxic substances or in formulas to restrain the toxicity of one component. Some two substances are each non-toxic on their own, but when brought together, they generate great toxicity that damages the body — and so on. These matters constitute the essential professional knowledge that all medical practitioners and pharmaceutical researchers must command, and their importance is such that they control the very juncture between life and death; not the slightest fraction can be taken lightly.

For a very long historical period, the Shennong Bencao Jing served as the textbook for physicians and pharmacists studying Chinese materia medica, or was placed in a position of paramount importance as a must-read text. The determinations of the properties of drugs and the descriptions of their functions and indications set forth in the book are extremely precise. The majority of the pharmacological theories and the principles of medicinal combination laid down in it remain, even today, important theoretical cornerstones of Chinese medicine and pharmacy. For modern TCM clinical practice, the exposition of the Shennong Bencao Jing still holds firmly grounded authority, and at the same time, it has become one of the indispensable reference works on the desks of medical practitioners.