The Eight Principles (八纲) refer to the eight categories of syndromes in Traditional Chinese Medicine (TCM): Yin, Yang, Exterior, Interior, Cold, Heat, Deficiency, and Excess. The differentiation based on these principles is one of the most fundamental methods of diagnosis and treatment in TCM. In the Qing Dynasty, Cheng Zhongling mentioned in “Medical Insights” that: “The essence of disease lies in the eight characters of Cold, Heat, Deficiency, Excess, Exterior, Interior, Yin, and Yang. Since the condition does not go beyond this, the method of differentiation also does not go beyond this.” The dominance of Yin or Yang and the imbalance of their entry and exit lead to a state of Deficiency or Excess in the body, while Cold and Heat are the most direct manifestations of this state. During clinical inquiries, the question of ‘Cold and Heat’ is always prioritized.Definition of Cold and HeatCold and Heat have two layers of meaning: one refers to the symptoms of Cold and Heat, and the other to the pathophysiological mechanisms of Cold and Heat. First, regarding the symptoms of Cold and Heat.Cold refers to symptoms of weakness such as fear of cold, cold limbs, poor spirit, spontaneous sweating, and diarrhea; Heat refers to symptoms of excess such as fever or subjective feeling of heat, aversion to heat, irritability, internal heat, dry stools, and foul breath. The “Huangdi Neijing” states: “When Yang is dominant, there is Heat; when Yin is dominant, there is Cold.”“Medical Insights” summarizes the specific manifestations of Cold and Heat as follows: “The Cold and Heat of a disease is entirely reflected in thirst and lack of thirst, whether thirst leads to urination or not, preference for hot or cold food, irritability and counterflow, the length and color of urine, the consistency of stools, and the pulse being slow or rapid. If there is thirst and the ability to urinate, a preference for cold food, irritability, short and red urine, and hard stools, the condition is Heat. If there is no thirst, or false thirst with inability to urinate, a preference for hot soup, cold hands and feet, clear and long urine, loose stools, and a slow pulse, the condition is Cold.”Secondly, regarding the pathophysiological mechanisms of Cold and Heat, the “Neijing” states: “Cold causes Qi to contract, while Heat causes Qi to leak.” It also states: “Cold causes the pores to close, preventing Qi from circulating, hence Qi contracts. Heat opens the pores, allowing the Wei and Ying Qi to communicate, leading to excessive sweating, hence Qi leaks.” Cold causes Qi to contract, while Heat causes Qi to leak; Cold causes the pores to close, preventing sweating, leading to a tendency towards Excess; Heat opens the pores, leading to excessive sweating, leading to a tendency towards Deficiency.Here, Cold and Heat correspond to the concepts of “injured (by) Cold” and “Wind” frequently used in the “Shanghan Lun”. Cold represents contraction and Excess, while Heat or Wind represents dispersion and Deficiency, which differs from the common understanding that Cold is often Deficient and Heat is often Excess. The “Shanghan Lun” and “Jinkui Yaolue” contain many examples utilizing the principles of Cold contraction and Heat dispersion. In cases where Cold and Heat are not clearly understood, it may seem counterintuitive. For example, after taking the Sanwu Baisan, it is noted: “If there is difficulty in taking hot porridge, and diarrhea does not stop, taking a cup of cold porridge will stabilize it.” The “Jinkui Yaolue” states: “If diarrhea does not stop, drinking a cup of cold water will stabilize it.” This applies the principle of Cold contraction to treat diseases with excessive sweating and diarrhea. Similarly, after taking Guizhi Decoction, it is advised to “sip hot porridge to assist the medicinal effect”; after taking Wuling San, it is advised to “drink warm water to promote sweating and recovery,” utilizing the characteristics of Heat dispersion to treat symptoms such as lack of sweating, difficulty urinating, and overall Qi stagnation.In summary, for diseases with Qi stagnation, Heat is beneficial for dispersing, while Cold is beneficial for constraining in cases of excessive dispersion. Therefore, using Ma Gui (Cinnamon) for warmth and dispersion, and Bai Hu (White Tiger) for cooling and constraining. The “Neijing” states: “Dispersing the exterior does not stray far from Heat, attacking the interior does not stray far from Cold.” In my clinic, I often encounter patients who experience diarrhea the day after eating spicy food, which is due to the internal presence of Damp-Heat; the spiciness triggers the diarrhea, indicating that Heat leads to Qi leakage.Transformation of Cold and HeatThe “Suwen: Water and Heat Acupuncture” states: “The Emperor asked: Why does injury from Cold lead to Heat? Qi Bo replied: When Cold is excessive, it generates Heat.” The “Suwen: Heat Discussion” states: “All Heat diseases are of the type caused by Cold.”Heat leads to Qi leakage, and Qi leakage leads to Deficiency, hence the fear of Cold. Cold leads to Qi contraction, and Qi contraction leads to Excess, hence the appearance of fever. Although referred to as injury from Cold, the symptoms manifest as severe fever; the more severe the Cold exposure, the more severe the fever.Cold and Heat are not as irreconcilable as ice and fire; rather, they transform into each other and are mutually causal. “When Cold is excessive, it generates Heat” may seem counterintuitive, hence later physicians interpreted it as “entering the interior to transform into Heat.” As long as one understands that “Cold causes Qi to contract, and Heat causes Qi to leak,” it can be understood that Cold stagnation will inevitably generate Heat, and Heat is generally caused by Cold. This is why the “Suwen: Heat Discussion” states: “All Heat diseases are of the type caused by Cold.” The discussion in the “Shanghan Lun” regarding the Taiyang Cold injury syndrome, whether there is already fever or not, follows this principle: there is an external cause of Cold exposure, which then leads to exterior Heat appearing, and further development may lead to both exterior Cold and interior Heat, or both being Excess, with treatment methods starting with Mahuang Decoction followed by the emergence of Daqinglong Decoction, Xiaoqinglong Jia Shigao Decoction, and Xiao Chaihu Jia Shigao Decoction, etc.Although the summer-heat syndrome is classified as Heat, it often presents with deficiency due to sweating. Clearing summer-heat formulas such as Qingshu Yiqi Decoction and Baihu Jia Renshen Decoction often contain tonifying herbs, as stated in the “Neijing”: “When Qi is abundant, the body is Cold; when Qi is Deficient, the body is Hot due to summer-heat.”Liu Wanshu in “Suwen Xuanji Yuanbing Shih” analyzed the relationship between the occurrence of Cold and Heat, stating: “The classics say: ‘When a person is injured by Cold, it leads to disease and Heat.’ This is because Cold injures the skin and hair, causing the pores to close tightly, leading to stagnation of Yang Qi, which cannot circulate, resulting in Heat. Therefore, when Cold injures the exterior, the Heat is on the exterior. It is advisable to use Mahuang Decoction or similar sweet, pungent, and warming herbs to disperse, allowing the pores to open, sweating to release Heat, and thus recovery. Any internal injury from cold substances, or when Yin dominates Yang, leads to disease and Cold; or when Cold and Heat clash, causing stagnation of Yang Qi in the stomach and intestines, leading to Heat; or there may be internal injury from cold substances leading to Heat, resulting in profuse sweating and cooling of the body, or mild symptoms that do not lead to other diseases, merely resulting in sourness in the stomach, commonly referred to as ‘vinegar heart.’In such cases, it is advisable to use warming herbs to disperse, similar to the meaning of dispersing the exterior, to open the stagnation in the stomach and intestines, allowing the Heat to disperse and harmonize.If one has a long-standing preference for sourness and it does not cease, it is not advisable to warm it; rather, it is better to use cold herbs to purge it, and then use cooling herbs to adjust it, allowing the Heat to dissipate and Qi to harmonize.Thus, sourness should not be consumed with sticky, greasy foods, as this can lead to stagnation and blockage of Yang Qi. For example, if food is left covered and heated, it becomes sour. It is advisable to consume vegetables, which can promote the smooth flow of Qi.Liu’s arguments deeply grasp the essence of the “Neijing”; it is no wonder that later generations referred to him as the “Master of Heat Diseases in Hejian.”From the above discussion, one can relate it to the first law of thermodynamics in physics, also known as the law of conservation of energy. It simply states: “Energy cannot be created or destroyed; it can only be transformed from one form to another or transferred from one object to another, while the total amount of energy remains constant.”Humans are warm-blooded animals with self-regulating mechanisms that always strive for a general stability of energy. When excessive energy enters the body, it must find ways to expel it, striving for a balance of entry and exit, such as through fever, sweating, and urination; there may also be symptoms such as irritability and insomnia, which are ways to expel energy through activity and emotion; or there may be symptoms such as rashes and ulcers, which are ways to release energy through the skin; or through tears, nocturnal emissions, and menstruation to expel energy. Any energy that cannot be expelled temporarily transforms into fat stored in the body, leading to obesity.Excessive energy entering the body does not simply disappear; it can only be expelled from the body or presented in another form, which manifests as physiological expressions or pathological symptoms, often as the body’s negative feedback compensation mechanism attempting to restore energy balance. Therefore, the pathological symptoms that appear in the body cannot simply be eliminated through direct confrontation; rather, one must trace back to the source and clear the root cause. Internal Heat can lead to loose stools and frequent bowel movements, as the body attempts to reduce internal Heat by increasing the frequency of bowel movements. It is not appropriate to use astringent herbs to stop diarrhea for two reasons: first, this type of diarrhea is difficult to stop; second, once the diarrhea slightly alleviates the internal Heat, it will seek another outlet, possibly presenting as sore throat, excessive sweating, irritability, etc. Therefore, this type of diarrhea should be treated with purgative and clearing herbs.Cold and Heat are merely external manifestations of disease; the statement “Cold is Heat, and Heat is Cold” cannot be completely established in some cases and requires accurate differentiation. For example, Zhang Zhongjing’s pungent and warm herbs eliminate great Heat, Li Dongyuan’s sweet and warm herbs eliminate great Heat, or Liu Wanshu’s pungent and cool herbs relieve Heat, and Wang Taifu’s strong water is the source of nourishing fire. The essence of disease lies in the Yin-Yang Deficiency and Excess; only by understanding the dynamics of Yin and Yang without being misled by appearances can one accurately identify the source of the disease and apply the correct treatment.Copyright Statement
- This article is selected from the official account of China Traditional Chinese Medicine News (ID: cntcm01), author: Zhen Weishuai from the People’s Hospital of Lixia District, Jinan City, Shandong Province.
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The various prescriptions and formulas mentioned in the text are for reference and learning purposes only. Non-professionals should not use them blindly.
Great article! I recommend everyone to read it.