The Eight Principles (Ba Gang) in TCM diagnosis refer to Yin-Yang, Exterior-Interior, Deficiency-Excess, and Cold-Heat, which are paired opposites. Yin-Yang pertains to the relationship between substance and function, Exterior-Interior pertains to location, Deficiency-Excess pertains to the primary and secondary conditions, and Cold-Heat pertains to physiological processes.
1. Yin-Yang
Many people discuss the Eight Principles without addressing Yin-Yang, claiming that Yin-Yang is the overarching principle, with Exterior, Excess, and Heat representing Yang, while Interior, Deficiency, and Cold represent Yin. This is incorrect.
In this context, Yin-Yang refers to the relationship between substance and function. Yin represents form, such as a person’s organs, limbs, trunk, skin, blood, and body fluids, all of which are considered Yin, or substance. Yang represents energy and movement. Whether a person has muscle strength, can speak with vigor, or has strong organ function, these are all aspects of Yang. The essence of Yin-Yang differentiation is to assess whether a person is deficient in substance or in Yang energy.
We often hear the term “Yin Deficiency with Excess Heat” or “Yin Deficiency with Internal Heat”; Yin Deficiency indicates insufficient body fluids that cannot contain heat, leading to its dispersion, hence the need to nourish Yin. Yang Deficiency, on the other hand, may manifest in a person who appears robust and overweight but lacks energy and strength.
Modern individuals often exhibit Yang Deficiency. Each generation has different constitutions; for instance, in the 1950s and 60s, many people suffered from Yin Deficiency due to material scarcity. Nowadays, with better nutrition, most people experience Yang Deficiency, which is why modern individuals generally do not require supplements. In the past, supplements were precious, with items like eggs reserved for postpartum recovery, leading to a perception of their value. Today, with a varied diet, the accumulation of waste in the body, and reduced physical activity, Yang Deficiency is prevalent, prompting the resurgence of the Fire God School’s Yang-nourishing theories.
However, moderation is key; excessive consumption of Fu Zi (Aconite) can deplete one’s essence. Historically, the Four Great Masters of the Jin and Yuan dynasties established four renowned schools of TCM, including the Fire School, Earth School, Yin-nourishing School, etc. These arose from the varying constitutions of people in different historical periods. Huang Yuan Yu Sheng, during the Qing Dynasty, noted that most illnesses were due to Cold-Dampness, with very few attributed to Warm-Dryness, which was specific to his time. It is also stated that Yin is often insufficient while Yang is often in excess, which may not hold true today.
In summary, balance between Yin and Yang is essential. Most illnesses begin with Yang Deficiency because if Yang is not deficient, a person will naturally seek food when hungry. When Yang is deficient, the ability to digest food diminishes, leading to Yin Deficiency and weight loss.
Prolonged Yin Deficiency can lead to a condition known as Yin Excess. Yin Excess refers to the accumulation of substance within the body, where insufficient Yang energy fails to expel waste or excess nutrients, resulting in stagnation. For instance, unwanted body fat can be considered a form of Yin Excess. Anything unwanted in the body can be termed Yin Excess. Yin Excess must be resolved by Yang, allowing Yang to penetrate Yin. If Yin Excess persists and Yang energy cannot enter, it may lead to localized heat.
The circulation of Qi and blood follows a twelve-hour cycle, with each organ corresponding to a specific time. If an organ is affected by excess, during its corresponding time, Yang energy cannot enter, leading to symptoms.
The Twelve Meridians Flow Sequence Song
“Lung in the Yin hour, Stomach in the Chen hour, Spleen in the Si hour, Heart in the Wu hour, Small Intestine in the Wei hour, Bladder in the Shen hour, Kidney in the You hour, Pericardium in the Xu hour, Liver in the Yin hour, Gallbladder in the Zi hour, and San Jiao in the Chou hour.”
This sequence indicates that if a person has excess in the lungs, they may wake up during the Yin hour (3-5 AM) because Yang energy cannot enter the lungs, causing them to awaken. “Yang emerges from Yin to awaken, while Yang enters Yin to sleep.”
Individuals with Yang Deficiency often fear cold, have insufficient central Qi, and experience fatigue, while those with Yin Deficiency tend to be thin, with Yang energy escaping, leading to symptoms like bone steaming and tidal fever.
Those with Yang Deficiency need to tonify Yang using Yang-nourishing herbs. Yang-nourishing herbs are not necessarily warming; any herb that increases energy is considered Yang-nourishing. Yin Deficiency requires Yin nourishment, but it is also essential to tonify Yang to enhance bodily functions, as Yin cannot act independently. The food consumed ultimately relies on the body’s Yang to transform it for absorption. When digestion is effective, Yin Deficiency will naturally resolve.
Generally, individuals do not require extensive Yin nourishment or expensive supplements. Simple remedies like ginger and jujube can suffice for nourishing fluids. Modern individuals consume milk daily, which negates the need for additional Yin nourishment. Yin Excess typically arises in the later stages of illness, requiring potent Yang-nourishing herbs to resolve it.
Yang is not inherently excessive; the stronger the function, the better.
This is the essence of Yin-Yang differentiation.
2. Exterior-Interior
Exterior-Interior differentiation assesses the location of the disease, determining whether it is superficial or deep. Exterior-Interior differentiation can be layered; in terms of the whole person, the skin, limbs, and trunk are considered Exterior, while the organs are Interior. Conditions like back pain, leg pain, and knee pain are Exterior, as are injuries from cuts or fractures, which are all considered superficial injuries. Organ diseases, such as liver, lung, or heart diseases, are classified as Interior. However, in the case of localized injuries, the skin is Exterior, while the bone is Interior. This distinction helps differentiate the layers of disease. Additionally, early symptoms of a cold, such as chills and aversion to cold, are considered Exterior, while gastrointestinal issues like vomiting, diarrhea, or constipation are classified as Interior.
Disease can progress from Exterior to Interior; for example, if a person is shot, the initial injury may be superficial, but if left untreated, the wound can worsen, damaging Qi and blood, ultimately affecting the organs and leading to death.
Disease can also progress from Interior to Exterior; for instance, when the body needs to expel toxins, it may manifest as skin conditions in advanced cancer.
Progression from Exterior to Interior indicates disease advancement, while progression from Interior to Exterior indicates disease resolution.
3. Deficiency-Excess
Deficiency-Excess differentiation identifies whether there is a lack or an abundance of substance. Deficiency indicates insufficiency, while Excess indicates an accumulation. For instance, Yang Deficiency signifies insufficient Yang energy, while Yin Excess indicates an accumulation of Yin.
Deficiency refers to the deficiency of Zheng Qi (Upright Qi), while Excess refers to the presence of Xie Qi (Evil Qi). For example, if a person has a weak stomach, it does not mean there is nothing in the stomach, but rather that the stomach Qi is insufficient, primarily due to inadequate digestive power, hence it is a deficiency of Zheng Qi. Stomach Excess indicates a blockage in the stomach, preventing digestion. The same applies to other organs; for instance, Intestinal Excess refers to constipation, while Bladder Excess refers to difficulty urinating. Stagnation of blood is also considered Excess. Phlegm and fluid retention are also forms of Excess. Deficiency of Qi and blood indicates insufficient Qi and blood, while Deficiency of body fluids indicates insufficient fluids. Deficiency refers to the insufficiency of the body’s Upright Qi, while Excess refers to the presence of abnormal substances, which are all considered Evil Qi.
4. Cold-Heat
Cold and Heat refer to the functional state of the body rather than its specific temperature. Cold indicates a low functional state, not necessarily that a person feels cold to the touch. However, if the function remains low for an extended period, it can lead to reduced temperature and cold extremities. This is why the term “Cold” is used. For example, if someone has Stomach Cold, measuring their temperature may not reveal a low reading; a person with Stomach Heat may have a stomach temperature that does not exceed 40 degrees Celsius. Heat refers to an overactive functional state.
Cold indicates inactivity, while Heat indicates excessive activity. Heat differs from Yang; Yang refers to the normal functioning of the body, while Heat indicates a state of overactivity.
Stomach Cold indicates insufficient stomach function, so enhancing stomach function requires the use of Gan Jiang (Dried Ginger) rather than Motilium. The properties of substances dictate their actions; warmth promotes movement, while cold causes stagnation. Cold blood leads to stagnant blood flow. Cold in the bladder results in weak urination. To treat frequent urination, urgency, or incomplete urination, warming the bladder is necessary. In women, Cold in the uterus can lead to menstrual irregularities and abdominal pain. Pain indicates blockage, while smooth flow indicates no pain; Cold leads to blockage.Excessive body function indicates Heat, characterized by excessive thirst, profuse sweating, flushed face, and coarse voice, all of which are signs of Heat. Dry, hard stools indicate Heat, while loose, pale stools with cold extremities indicate Cold.
Cold is often a primary condition, such as Stomach Cold or Kidney Cold, indicating insufficient function. Heat can be either primary or secondary. Primary Heat indicates overactivity of the body’s functions, leading to excessive metabolic activity, such as in Warm Diseases, where a person may sweat profusely while also having a fever, indicating excessive metabolic activity. To treat primary Heat, one should not use cold herbs directly to clear it but rather to restrain and consolidate the fire. Secondary Heat arises from blockages, such as Stomach Heat, which is not due to overactivity but rather due to the stagnation of food leading to heat production. This type of Heat can be cleared, but the most important aspect is to ensure smooth flow; once the pathways are clear, there will be no further heat production.
When treating Cold and Heat, the focus is on the body’s functions rather than directly lowering or raising body temperature. It is not as simple as drinking hot water to treat Stomach Cold or consuming ice to treat Stomach Heat.
However, external factors of Cold and Heat can also affect the body’s functions. For instance, prolonged consumption of cold foods can cause the stomach to contract, impairing its function, similar to how cold weather causes blood vessels to constrict, slowing circulation and leading to cold extremities.
All diseases involve the interplay of primary and secondary factors, but we treat the primary rather than the secondary. We say that fruits are cold in nature; the term “nature” refers to the properties of substances and their effects on the body, not their actual temperature. Fruits are cold in nature, and cooking them does not change their inherent properties. Fruits inhibit the absorption of nutrients in the intestines, thus suppressing digestive function.
The reason the Eight Principles do not include Dryness and Dampness is that the Eight Principles are centered on the individual, ultimately focusing on the person rather than the disease. TCM treats people, while Western medicine treats diseases; the Eight Principles also focus on the individual rather than the disease. Dryness and Dampness follow the same principle; they represent an obstruction in the body’s fluid circulation, similar to phlegm and blood stagnation. If water does not transform into Qi, and fluids do not distribute throughout the body, it leads to Dampness and Dryness. No herb can directly extract Dampness from the body, except perhaps for consuming quicklime. It is also not as simple as drinking excessive water to alleviate Dryness. Treating Dampness and Dryness follows the same principle; both require the movement of the body’s fluids. Thus, the Inner Canon states that pungent flavors moisten Dryness because pungent flavors promote dispersal and can stimulate fluid movement, thereby alleviating Dryness.
In summary, the Cold and Heat of the Eight Principles differ from the Cold and Heat of the Six Qi. The Six Qi refers to external pathogenic factors, while the Cold and Heat of the Eight Principles refer to the primary conditions of the body. The differentiation of Yin-Yang, Exterior-Interior, Deficiency-Excess, and Cold-Heat is fundamentally based on the primary condition. If Yin is insufficient, nourish Yin; if Yang is insufficient, nourish Yang. Treat conditions on the surface with surface methods, and treat internal conditions with internal methods. For Deficiency, tonify; for Excess, drain. For Cold, warm; for Heat, cool.