Diagnosis and treatment based on syndrome differentiation is a fundamental principle in Traditional Chinese Medicine (TCM) for understanding and treating diseases. The direct aim of syndrome differentiation is treatment, which unifies diagnosis and therapy. Syndrome differentiation is not legislated for a specific disease or category of diseases but applies universally to all diseases, embodying general principles.
Throughout its historical development, TCM has formed various methodologies for syndrome differentiation, such as Liujing Bianzheng (Six Meridians Differentiation), Bagang Bianzheng (Eight Principles Differentiation), Sanjiao Bianzheng (Three Jiao Differentiation), and Weiqiyingxue Bianzheng (Defensive Qi, Nutritive Qi, and Blood Differentiation), enriching the clinical methodologies of TCM. Among these, Bagang Bianzheng serves as the overarching principle of all differentiation methods and is a prerequisite for learning and applying TCM differentiation methods. In this article, I will attempt to explain the meaning of Bagang Bianzheng from the perspectives of clinical symptomatology and therapeutics, exploring its application methods in clinical practice, providing references for TCM differentiation methodology and clinical therapeutics. Any shortcomings in this discussion are humbly acknowledged.
From the perspective of TCM syndrome differentiation, all diseases can be understood in terms of disease nature and disease location. Disease location refers to the site of the body’s symptomatic response, which differs from the anatomical site of the cause and physiological pathology. In terms of syndrome differentiation, disease location is divided into Shang (Exterior), Li (Interior), and Ban Shang Ban Li (Half Exterior Half Interior). For example, in the case of lobar pneumonia, the cause is bacterial infection, and the site of the cause is in the lungs; however, when initial symptoms such as fever, chills, and floating pulse are observed, the differentiated disease location is at the exterior, which is a distinction.
Disease nature refers to the attributes of the disease, determined by the symptoms arising from the conflict between the righteous Qi and pathogenic factors, classified as Yin-Yang, Cold-Heat, Deficiency-Excess, which are not attributes of the pathogenic factors themselves.
Among the Eight Principles, the attribute of Yin-Yang is paramount, encompassing a pair of opposing yet complementary attributes that can be coordinated under Yin-Yang. Thus, Deficiency-Excess, Cold-Heat, and Interior-Exterior can all be categorized under the aspect of Yin-Yang. Conditions manifesting as excessive or hyperactive are classified as Yang conditions, while those showing deficiency or decline are classified as Yin conditions. Therefore, although diseases are complex and variable, in summary, if the syndrome is not Yin, it is Yang. This allows for a detailed discussion of the meanings of Interior-Exterior, Cold-Heat, and Deficiency-Excess from both symptomatology and therapeutics.
Interior-Exterior
The Interior-Exterior aspect of disease location reflects the site of symptomatic response, distinct from the site of the cause, and also differs from the pathological changes in modern anatomy or physiology. Clinically, the method of distinguishing disease location primarily relies on the correlation between symptoms; however, when symptoms are insufficient for analysis, we often need to rely on pulse diagnosis. This method of using pulse to differentiate Interior and Exterior is referred to as the “Unique Pulse Method,” which involves identifying unique pulse characteristics from the three positions of the pulse. For instance, if the left pulse at the cun position is floating, while the guan and chi positions are deep, the cun pulse is distinct from the guan and chi pulses, indicating a possible exterior condition; if the chi pulse is uniquely floating, it suggests a possible interior condition; if the guan pulse is uniquely floating, it indicates a possible half exterior half interior condition. The significance of the Unique Pulse Method in therapeutics can be summarized as follows: a strong floating cun pulse indicates an exterior condition, treated with exterior-releasing methods; a strong floating guan pulse indicates a half exterior half interior condition, treated with harmonizing methods; a strong floating chi pulse indicates an interior condition, treated with clearing methods. For example, in the Shanghan Lun, the 24th section states, “In Taiyang disease, after purging, if the pulse is rapid and the chest is full, Gui Zhi should be used without Shao Yao to treat it.” Here, the rapid pulse indicates a floating cun pulse, thus it is treated as an exterior condition, still using exterior-releasing methods, but due to the accompanying fullness in the chest, Shao Yao is omitted, leading to the use of Gui Zhi without Shao Yao decoction.
Cold-Heat
Yin-Yang is a broad category, while Cold-Heat and Deficiency-Excess are more specific subcategories. In terms of Cold-Heat, if the body reflects cold signs, it is termed a cold syndrome; if it reflects heat signs, it is termed a heat syndrome. Cold represents a deficiency state, belonging to Yin, thus cold conditions must be Yin; heat represents an excess state, belonging to Yang, thus heat conditions must be Yang. However, broadly speaking, Yin conditions do not necessarily manifest as cold signs, nor do Yang conditions necessarily manifest as heat signs. The best way to differentiate Cold and Heat is to consider all symptoms collectively; however, when symptoms are insufficient or difficult to distinguish, the simplest clinical method for differentiating Cold and Heat is to observe the moisture or dryness of the tongue. A moist tongue coating often indicates a cold syndrome, while a dry tongue coating often indicates a heat syndrome, as cold syndromes retain water, leading to a moist tongue; heat syndromes consume and evaporate fluids, leading to dryness. Therefore, the color of the tongue coating, whether yellow or white, is not the most powerful evidence for distinguishing Cold and Heat; rather, differentiating based on moisture and dryness has greater clinical practical value. Generally speaking, clear, cool, tasteless, and non-sticky body fluids are often cold, while turbid, hot, flavorful, and sticky fluids are often heat. For example, in the case of Xiao Qing Long Tang, the phlegm is clear and thin, indicating cold water, thus hot herbs should be used; in the case of Ma Xing Shi Gan Tang, the expectorated phlegm is yellow and thick, indicating heat, thus Sheng Shi Gao should be used. This is a simple technique for differentiating Cold and Heat.
Deficiency-Excess
Further discussing Deficiency and Excess, deficiency refers to the person’s deficiency, while excess refers to the disease’s excess. For instance, if the disease has not yet resolved, but the person’s energy is already depleted, and the disease reflects a state of deficiency and decline, it is termed a deficiency syndrome. Conversely, if the disease progresses vigorously while the person’s energy remains intact, and the disease reflects a state of fullness, it is termed an excess syndrome. The most direct way to differentiate Deficiency and Excess is through pulse diagnosis; a deep, strong pulse indicates an excess syndrome, while a deep, weak pulse indicates a deficiency syndrome. In the context of the Eight Principles Differentiation, a strong pulse indicates a Yang syndrome, while a weak pulse indicates a Yin syndrome; in the context of the Six Meridians Differentiation, a strong pulse often belongs to the three Yang diseases, while a weak pulse often belongs to the three Yin diseases; in the context of organ differentiation, a strong pulse often belongs to the six fu organs, while a weak pulse often belongs to the five zang organs. In terms of treatment, Yang syndromes should be suppressed, while excess syndromes, being hyperactive, can be directly suppressed; deficiency syndromes, being deficient and hyperactive, should not be directly suppressed and often require cooling and nourishing herbs for support; Yin syndromes, characterized by weak pulses, should be treated with warming support as a general principle. For example, in the Jin Gui Yao Lue, the section on Yi Yi Ren, Fu Zi, and Bai Jiang San states, “In the case of intestinal abscess, the body is tense, the abdominal skin is tight, and upon palpation, it feels soft like a swelling, with no accumulation in the abdomen, no fever, and a rapid pulse; this indicates the presence of pus in the abdomen,” where the pulse should be weak and rapid; in the case of Da Huang and Mu Dan Tang, “If the lower abdomen is swollen and hard, palpation causes pain like a sting, urination is normal, and there is occasional fever and spontaneous sweating, with a slow and tight pulse; this indicates that the pus has not yet formed, and it should be purged, and there will be blood,” where the slow and tight pulse should be strong and slow; if the pulse is weak, Da Huang and Mu Dan Tang should not be administered. This is a practical application of using pulse diagnosis to differentiate Deficiency and Excess to select appropriate formulas.
In summary, Bagang Bianzheng is the overarching principle of differentiation methods, the most fundamental differentiation method, and the source of clinical treatment implementation. In the clinical differentiation and treatment process, only by clarifying the attributes of the Eight Principles of the disease can one distinguish Cold-Heat and Deficiency-Excess, thereby selecting the appropriate treatment methods. Furthermore, Bagang Bianzheng holds significant importance for the differentiation system of classical formulas; it encompasses the Six Meridians Differentiation, where each meridian contains the meanings of the Eight Principles. The Six Meridians are a refinement and interweaving of the Eight Principles; clarity in the Eight Principles leads to clarity in the Six Meridians, and clarity in the Six Meridians leads to clarity in clinical differentiation and treatment methods, with formulas arising from methods and medicines established according to formulas, thus clarifying the process of syndrome differentiation and treatment.
（Author: Zhang Qingjun, Zhang Qingjun Integrated Traditional Chinese and Western Medicine Clinic, Tangyin County, Henan Province; Zhai Huiqi, Guangzhou University of Chinese Medicine）