Ancient physicians, through long periods of time and extensive practice in preventing and treating diseases for the laboring masses, have produced invaluable texts such as the “Tang Ye Jing” (Classic of Decoction) and “Shang Han Za Bing Lun” (Treatise on Cold Damage and Miscellaneous Diseases). These texts, validated through countless repetitions and proven effective, contain irreplaceable formulas known as classical prescriptions. Only those that can be repeatedly verified can be called scientific. The prescriptions are derived from theoretical principles; good theories must have good formulas, and classical patterns of prescriptions will endure through time, as their purpose is to cure diseases. Successful formulas are always based on successful theories. The successful theories are found in Zhang Zhongjing’s writings, not outside of them. One can assess a physician’s theoretical level by examining their prescriptions.
Chapter One: Eight Principles
The Eight Principles refer to the categories of Yin, Yang, Exterior, Interior, Cold, Heat, Deficiency, and Excess, which serve as the framework for differentiation of syndromes. During the era of herbal decoctions, the Eight Principles were already recognized for diagnosing and treating diseases. Zhang Zhongjing added the concept of “half exterior, half interior” in Article 148, which, by numerical count, should be nine principles; however, it is commonly referred to as the Eight Principles since the terms “exterior” and “interior” encompass the half exterior, half interior concept. The Eight Principles address the attributes of syndromes; without differentiating the Eight Principles, one cannot diagnose diseases.
When the human body is afflicted, there is a struggle between the righteous and the evil, which must manifest as symptoms. Where there are symptoms, there must be Cold, Heat, Deficiency, or Excess conditions, and where there are conditions, there are fixed locations reflecting these conditions in the Exterior, Interior, or half Exterior, half Interior. Without conditions, there are no disease locations; without disease locations, there are no conditions. Therefore, without symptoms, there can be no differentiation of the Eight Principles, and the Six Meridians of Cold Damage do not exist. Zhang Zhongjing’s contribution was to establish the location of half exterior, half interior, thus inventing the “Six Meridians of Cold Damage”; hence, it is said that the Six Meridians of Cold Damage arise from the Eight Principles.
In the “Shang Han Lun” (Treatise on Cold Damage), the concepts of Exterior and Interior are absolute, while Internal and External are relative. For instance, when Taiyang and Shaoyang are combined, Shaoyang is considered within the Exterior; when Shaoyang and Yangming are combined, Shaoyang is considered outside the Interior. The ancient understanding of the Exterior pertains to the upper body, while the Interior refers to the digestive tract. Without understanding the Exterior and Interior, there is no pathway to treat diseases. A physician capable of reducing fever is a skilled physician because they clearly distinguish between Exterior, Interior, Cold, Heat, Deficiency, and Excess. In clinical practice, as long as the differentiation of syndromes based on Exterior, Interior, Cold, Heat, Deficiency, and Excess does not deviate significantly, there will be a certain degree of efficacy. Cold and Heat have their constants, while Deficiency and Excess do not. Deficiency Cold is Yin, while Deficiency Heat is the opposite, Yang; Excess Heat is Yang, while Excess Cold is the opposite, Yin. There are conditions that are neither Cold nor Heat, or neither Deficient nor Excess, but there are absolutely none that are neither Yin nor Yang.
There are two types of disease progression: one that can heal naturally without treatment, and another that requires treatment to heal. Traditional Chinese Medicine observes the clinical manifestations, which are the symptoms. Without symptoms, there can be no differentiation. Differentiation begins with distinguishing between Exterior and Interior, and half Exterior, half Interior; one must first clarify the disease location before differentiating Deficiency, Excess, Cold, and Heat. Overall, one must have an understanding of the disease syndromes, which is called differentiating Yin and Yang. Without differentiating Exterior and Interior (including half Exterior, half Interior), there is no way to treat diseases.
Zhang Zhongjing states, “The disease is in the Exterior” (Article 51) and “Evil is in the skin” (from “Jin Kui Yao Lue: On Wind and Joint Diseases, Section Five”); this summarizes the trend of disease development in the Exterior, not the specific symptoms in the Exterior. Because there can be many symptoms in the Exterior, one must continue to differentiate Cold, Heat, Deficiency, and Excess, and then differentiate the formulas and syndromes. In clinical practice, isolated Exterior symptoms are rarely seen; strictly speaking, they do not exist. The Exterior symptoms observed often have some accompanying symptoms.
Leaving aside the Exterior and Interior, the area of half Exterior, half Interior is vast, encompassing many organ pathologies in the thoracic and abdominal cavities, where many internal diseases occur, warranting further study. Nowadays, most physicians cannot recognize Shaoyang disease, nor do they understand it, yet Shaoyang disease objectively exists and must be treated with Chai Hu (Bupleurum) decoction.
Zhang Jingyue’s “Jingyue Quanshu” discusses the Eight Principles, emphasizing warming and tonifying the Kidney Essence. Cheng Zhongling’s “Yixue Xinwu” summarizes the Eight Principles using the “Neijing” (Inner Canon) and “Nanjing” (Classic of Difficulties). Their discussions of the “Eight Principles” are unrelated to Zhang Zhongjing’s writings.
Chapter Two: Six Meridians
The “Six Meridians of Cold Damage” are a specific manifestation of the Eight Principles and can also be seen as a classification of syndrome groups. The “Six Meridians of Cold Damage” are the Eight Principles, which categorize numerous syndromes into six meridians, and within the six meridians, there are also the Eight Principles; the two are inseparable. Thus, the Six Meridians of Cold Damage arise from the Eight Principles.
If the righteous and evil struggle within the vast surface of the body, including the skin, muscles, and bones, this is the location of Exterior disease. Symptoms that manifest in the Eight Principles as Yang, Excess, and Heat are referred to as the active Taiyang disease, such as floating pulse, floating and rapid pulse, floating and tight pulse, floating and slow pulse, stiffness and pain in the head and neck with aversion to cold, sweating with aversion to wind, aversion to cold with fever, headache, body aches, sore throat, or cough or wheezing, etc.
If the symptoms manifest in the Eight Principles as Yin, Deficient, and Cold, they are referred to as the active Shaoyin disease, such as fine and weak pulse, desire to sleep, aversion to cold, curled up posture, irritability, moist mouth, sore throat, etc.
The part of the lung that inhales air, including the throat, respiratory tract, and alveoli, is connected to the external environment; both Cold and Warm evils can struggle here, which should belong to the location of Exterior disease, and there are also distinctions between Taiyang disease and Shaoyin disease. The part of the lung that cannot contact air should belong to the half Exterior, half Interior disease location.
If the righteous and evil struggle within the digestive tract, from the throat, esophagus, stomach, intestines to the anus, this is the location of Interior disease. Symptoms that manifest in the Eight Principles as Yang, Excess, and Heat are referred to as the active Yangming disease: such as deep pulse, deep and solid pulse, fullness in the stomach, abdominal distension, irritability, hard stools, fever, excessive sweating, thirst, tidal fever, not aversive to cold but aversive to heat, and blood in the stool, etc. Symptoms that manifest in the Eight Principles as Yin, Deficient, and Cold are referred to as the active Taiyin disease: such as weak pulse, abdominal fullness with vomiting, inability to eat, significant self-relief, and intermittent abdominal pain, etc.
If the righteous and evil struggle between the Interior and Exterior, within the vast thoracic and abdominal cavity, this is the location of half Exterior, half Interior disease. As stated in Article 97: “Evil qi enters and clashes with righteous qi, binding under the ribs.” Article 148 states: “This is half in the Interior and half in the Exterior.” Symptoms that manifest in the Eight Principles as Yang, Excess, and Heat are referred to as the active Shaoyang disease: such as wiry pulse, wiry and thin pulse, bitter mouth, dry throat, no hearing in both ears, alternating chills and fever, fullness in the chest and ribs, lack of desire to eat or drink, irritability, and nausea, etc. Symptoms that manifest in the Eight Principles as Yin, Deficient, and Cold are referred to as the active Jueyin disease: such as faint and weak pulse, pulse that is thin and about to disappear, thirst, qi rising to the heart, heat in the heart, hunger without desire to eat, vomiting of roundworms, cold extremities, and cold with nausea, etc.
There is much debate in the TCM community regarding Jueyin disease, with significant differences of opinion. My explanation is that this disease only has the “Ti Gang” (Article 326) and Article 329. Most of the texts suggest Jueyin disease arises from mismanagement and mistreatment, leading to unresolved “Cold Damage” and decline in organ function, evolving into the “Ti Gang” discussion as a Deficiency syndrome, which pertains to Xiao Chai Hu Tang (Minor Bupleurum Decoction). “Thirst” and “hunger” are both Deficiency syndromes; “thirst” is not due to heat in the Yangming Interior but rather a self-rescue through drinking; “hunger” indicates a lack of nourishment from food and water. “Lack of desire to eat” indicates weakened gastrointestinal function, unable to digest food and water.
“Vomiting of roundworms” was a common disease in ancient times. Due to difficulties in obtaining fire, many consumed raw and cold foods and drank unboiled water; due to the lack of toilets, roundworm eggs would spread with the wind, leading to rampant roundworm disease. In severe cases of Jueyin disease, vomiting roundworms is not surprising.
The metabolic function decline of the organs in the half Exterior, half Interior area must inevitably affect the extreme Deficiency of the stomach and intestines, but it is not an Interior disease. Although there may be abdominal pain, using purgatives will only drive the evil into the Interior, causing continuous diarrhea. The decline in function must lead to an increase in Cold qi, which reverses and obstructs the Yang qi in the heart, hence the “heat in the heart”.
In summary, the condition of Jueyin disease is critical; the term “Jue” (reversal) appears nearly a hundred times in the Jueyin section, and the etiology is summarized as “Yin and Yang qi not connecting smoothly”, indicating the functional decline of many organs in the thoracic and abdominal cavity. Zhang Zhongjing’s discussion of the death certificates for Cold Damage includes 21 articles, with Jueyin disease accounting for the most, with 8 articles, plus 4 articles of “difficult to treat” syndromes. Therefore, the formulas provided by Zhang Zhongjing are few, and one can only “treat according to the symptoms”.
Despite the complexity of pathogenic factors and the variety of diseases, the occurrence and development of diseases generally fall within the scope of the Eight Principles and Six Meridians. Regardless of the disease, all diseases arise from the three disease locations of Exterior, Interior, and half Exterior, half Interior. That is, all diseases do not stray from the Eight Principles, and all diseases do not stray from the Six Meridians, which can serve as the fundamental principles for treatment.
Traditional Chinese Medicine consistently applies one method to treat multiple diseases and multiple methods to treat one disease, which is a strong testament to this spirit. Overall, for common diseases, frequently occurring diseases, and chronic diseases, we only recognize the manifestation of symptoms regardless of what Western medicine labels them. In differentiating and prescribing, as long as one adheres to the standards of differentiation based on the Eight Principles and Six Meridians without significant deviation, there will be a certain degree of efficacy. Conversely, it becomes difficult to ascertain.
The “Six Meridians of Cold Damage” refers to the diseases of the six meridians. This “disease” can be understood as “syndrome”, because each meridian disease has its pulse and syndrome, discussing “pulse and syndrome treated together”, and is absolutely not about “meridians” or “meridian pathways”. I do not agree that “it developed from the differentiation of the six meridians in the ‘Suwen: Discussion on Heat'”. The “Discussion on Heat” only discusses the Yang, Excess, and Heat syndromes of the Exterior and Interior, namely Taiyang and Yangming, without Zhang Zhongjing’s half Exterior, half Interior syndromes and the three Yin syndromes (Shaoyang, Shaoyin, Taiyin, Jueyin), thus omitting four syndromes from the “Zhang Zhongjing’s Six Meridians”. Two-thirds are missing. Some textbooks insist on comparing the two, which is difficult to justify.
The “Heat Discussion Six Meridians” has meridian pathways and syndromes, but lacks pulse manifestations. The “Zhang Zhongjing’s Six Meridians” has syndromes and pulse manifestations, but lacks meridian pathways. The “Heat Discussion” superficially discusses heat diseases affecting the meridians, without specific treatment methods. Thus, Zhang Zhongjing’s texts are unrelated to meridians.
The development of Traditional Chinese Medicine originally began with acupuncture and later evolved to decoctions; the naming of diseases by meridians has been a long-standing habit. The “Shang Han Lun” continues to use this division, which is not to be blamed; the entire text consistently embodies the spirit of differentiation based on the Eight Principles, which is evident. Unfortunately, most annotators insist on clinging to the names of meridians, associating them with various theories from the “Neijing”, thus failing to clarify the systematic rules of differentiation and treatment, let alone perceive its spiritual essence. Its essence is: the Six Meridians arise from the Eight Principles, and the Six Meridians are the Eight Principles. In the “Shang Han Lun”, there are organs without viscera, discussing their parts but not fully corresponding to their vessels, discussing diseases affecting their functions but not harming their bodies.