The concept of Yin and Yang is extensively used in Traditional Chinese Medicine (TCM), so understanding the meaning of “Yin” and “Yang” is essential for studying TCM.
The Balance and Imbalance of Yin and Yang
The balance of Yin and Yang is a traditional Chinese concept that can be used to explain various phenomena, not just in TCM. Essentially, it refers to the appropriate degree of various indicators necessary for normal functioning.Maintaining indicators within an appropriate range for proper functioning is called balance. When indicators exceed the normal range, resulting in dysfunction, it is termed imbalance.This is a common and straightforward principle in life.If you are unclear about the concept of Yin and Yang balance, it can lead to a series of confusions while learning TCM. Therefore, it is crucial to clearly explain the balance of Yin and Yang.Previously, explanations of Yin and Yang often involved “mystifying the mysterious,” using one incomprehensible concept to explain another, ultimately failing to clarify the matter. Thus, we will use a familiar example to explain “Yin and Yang.” Below is an example of temperature balance in a room.Assuming we have a 20 square meter room used as a bedroom.We want to control the room temperature around 25 degrees Celsius, with fluctuations not exceeding 5 degrees, meaning it should be between 20–30 degrees, which is a comfortable temperature range.If the room temperature fluctuates between 5 to 10 degrees, it indicates a problem, but it is not severe. For instance, if it drops to between 15 and 20 degrees, it is termed cold; if it rises to between 30 and 35 degrees, it is termed hot. Both cold and hot are seen as affecting the living function, but it is still bearable.If the temperature fluctuates beyond 10 degrees, falling below 15 degrees or rising above 35 degrees, it is considered a loss of living function.To achieve this temperature control, we have equipped the room with a 2P air conditioner and a 3KW electric heater to regulate the room temperature.The heater can raise the temperature, referred to as Yang. The air conditioner can lower the temperature, referred to as Yin.
This small example encompasses common elements of Yin and Yang, and here is the explanation:1、This example first establishes the function, which is the bedroom, intended for human habitation.This point is crucial because the function determines the balance point. If the room’s function is for living, the temperature balance point is 25 degrees. If the room is used as a cold storage, the balance point should be set at -10 degrees.Therefore, when discussing Yin and Yang, we must first clarify the function.Different functions determine different balance points, which in turn determine the Yin and Yang attributes of different things.
2、Only after determining the balance point can we discuss Yin and Yang: In this example, with 25 degrees as the balance point, any object below this temperature is considered Yin, such as an object around 10 degrees placed in the room, as it can lower the room temperature. However, if the room is used as cold storage, with a balance point at -10 degrees, then an object around 10 degrees would be considered Yang, as its temperature is higher than the balance point. Thus,an object’s classification as Yin or Yang is relative to its balance point.In our textbooks, we explain Yin and Yang using basic attributes and the inherent Yin and Yang properties of objects, which can be abstract and difficult to understand. For example, textbooks state that heat belongs to Yang and cold belongs to Yin. But what temperature is considered hot, and what temperature is considered cold? This implicitly uses human body temperature as the balance point, where temperatures above body temperature are hot (Yang) and those below are cold (Yin). If we change the object, the balance point changes, and the original Yin and Yang classifications will also change. An object at 10 degrees may feel cool to a person, thus classified as Yin. However, if placed in a cold storage, it would be classified as Yang. Therefore, the attributes of Yin and Yang are relative and variable; the same object can have different Yin and Yang properties relative to different balance points. The Yin and Yang properties of any object are determined by the differences in its relative balance point.
The basic attributes of Yin and Yang can be summarized as follows:Anything that is moving, rising, floating, outward, hot, bright, and formless belongs to Yang;
Anything that isstatic, descending, sinking, inward, cold, dark, and tangible belongs to Yin.
Thus, heaven is above and formless belongs to Yang; earth is below and tangible belongs to Yin.
The sun is bright and hot, thus belongs to Yang; the moon is dim and cold, thus belongs to Yin.
In diseases, heat syndrome, excess syndrome, and exterior syndrome belong to Yang; cold syndrome, deficiency syndrome, and interior syndrome belong to Yin.The basic attributes of Yin and Yang are absolute and fixed, but the Yin and Yang properties of things themselves are relative and variable.
This relativity and variability of the Yin and Yang properties of things manifest in two ways: on one hand, under certain conditions, related relative things can transform into each other, meaning Yin can transform into Yang and vice versa; on the other hand, it reflects the infinite divisibility of Yin and Yang properties within a single entity, i.e., “Yin contains Yang, Yang contains Yin, and within Yin and Yang, there are also Yin and Yang” (from “Classics of Yin and Yang”).
Describing and Regulating Yin and Yang Imbalance
In TCM, deficiency and excess are used to describe the nature of the causes of imbalance, while tonification and purgation are used to describe the methods of regulating imbalance.
Deficiency
What should be present but is lacking is termed deficiency (“When essence and qi are depleted, it leads to deficiency”). Deficiency can lead to insufficient ability to regulate balance, resulting in imbalance due to general disturbances.
In our example, if the air conditioner malfunctions and its cooling capacity decreases by half, leading to an inability to provide sufficient cooling when the summer temperature rises, this is deficiency, as the air conditioner is Yin, thus it is Yin deficiency.
The air conditioner failing to provide enough cooling results in the room temperature rising above 30 degrees, exceeding the normal range, termed heat.
This heat caused by Yin deficiency (insufficient air conditioning capacity) is termed deficiency heat.
Similarly, if the heater malfunctions and its heating capacity decreases, it is Yang deficiency. This leads to the room temperature dropping below 20 degrees in winter, termed cold. Cold due to Yang deficiency is termed deficiency cold.Yang deficiency manifests as deficiency cold; Yin deficiency manifests as deficiency heat.“Introduction to TCM – Pathogenesis”
Excessive deficiency is termed depletion. Extreme Yin deficiency is termed depletion of Yin. Extreme Yang deficiency is termed depletion of Yang.
Excess
What should not be present but is present is termed excess (“When pathogenic qi is abundant, it leads to excess”). Excess indicates that the room is subjected to abnormal disturbances, so even if its ability to self-regulate balance is normal, it can still become imbalanced due to excessive disturbance.
In this example, if both the air conditioner and heater are functioning properly, but someone starts a fire in the room, causing the temperature to rise, even with the air conditioner running at full capacity, it cannot maintain the room temperature within a reasonable range. The temperature rises above 30 degrees, becoming “heat.” This heat is caused by the unwanted fire, thus it is termed excess heat.
Similarly, if a large block of ice is placed in the room, causing the temperature to drop below 20 degrees, even with the heater turned up, it cannot regulate the temperature, resulting in “cold.” This cold is termed excess cold.
Methods for Regulating Balance (Tonification and Purgation)
Understanding the principles of deficiency and excess, cold and heat, naturally leads to understanding the methods of regulation.
If the issue lies with the air conditioner or heater, then repairing them is the solution, which is tonification. The air conditioner represents Yin, so repairing it is tonifying Yin. The heater represents Yang, so repairing it is tonifying Yang.
If there is excess fire or ice in the room, then removing them is the solution, which is purgation. Removing the fire is termed “purgation of heat,” and removing the ice is termed “dispersing cold.”
Thus, it is said, “Deficiency is to be tonified, excess is to be purged.” In general, tonifying deficiency is called supporting the righteous, while purging excess is called expelling the evil. Therefore, the methods of TCM are fundamentally about supporting the righteous and expelling the evil.
Coexistence of Deficiency and Excess
Since deficiency indicates insufficient righteous qi and excess indicates excessive pathogenic qi, both deficiency and excess can coexist in the same area; different areas can have deficiency in one and excess in another. Generally, pure deficiency of righteous qi or pure excess of pathogenic qi often represents the initial stage of a disease, with a single cause, making treatment relatively simple. Chronic diseases, geriatric diseases, and severe illnesses often involve the coexistence of deficiency and excess, with both deficiency and excess present in one area, as well as differing deficiency and excess in different areas. Addressing such issues requires determining the priority of tonification or purgation based on severity, or using both tonification and purgation together. If both are used, there can be equal strength in tonification and purgation, or a stronger tonification with lighter purgation, or vice versa.
Incorrect Regulation
It is crucial to distinguish between deficiency and excess before applying the corresponding tonification or purgation methods; if misjudged, for example, mistaking excess heat for deficiency cold and applying tonification (increasing heating), it will exacerbate the situation, causing the temperature to deviate further from the balance point. Alternatively, if deficiency cold is misjudged as excess heat and purgation methods are applied, it can lead to even more severe problems.
In Yangming disease, inability to eat is caused by deficiency cold in the stomach… The physician misjudges… with hands and feet sweating profusely, and the stool initially hard then loose, mistaking it for excess heat in the stomach, recklessly using bitter cold purgatives, further depleting the middle qi, causing disharmony in the stomach and leading to regurgitation, which is termed “attacking the heat must lead to regurgitation.”… The disease fundamentally belongs to deficiency cold in the stomach, and purging attacks violate the principle of deficiency, resulting in regurgitation.“Commentary on Treatise on Cold Damage – Article 194”
Therefore, one must not allow deficiency to become more deficient (deficiency deficiency) or excess to become more excessive (excess excess); avoiding the errors of deficiency deficiency and excess excess is a fundamental principle of TCM.
“Do not have excess excess, do not have deficiency deficiency, as it brings calamity to humanity, do not cause evil, do not lose the righteous, and ensure longevity.”“Huangdi Neijing – Treatise on the Five Constant Regulations”Zhang Jingyue said: “In human diseases, there are no more than exterior and interior, cold and heat, deficiency and excess; these six words encompass everything. Among these six, deficiency and excess are the most important, as all exterior syndromes, interior syndromes, cold syndromes, and heat syndromes all have deficiency and excess. If one can understand exterior and interior cold and heat and also discern deficiency and excess, then thousands of diseases can be unified, and the methods of treating diseases are no more than attacking and tonifying, using attack and tonification, without exceeding deficiency and excess.”“Commentary on Huangdi Neijing – Theory of Treatment – Tonifying Deficiency and Purging Excess”It is said: “Deficiency deficiency, excess excess, tonify the insufficient, reduce the excessive,” this is its meaning. The remaining organs follow this principle.“Jinkui Yaolue”
Methods of tonifying may carry the risk of retaining evil. For example, if we want to tonify a water source, but the water does not flow to that area, it may lead to excess water in areas that do not need it, thus inadvertently introducing pathogenic qi. Purgation methods often harm the righteous. For instance, if we want to eliminate waste water, we may also inadvertently remove good water, thus harming the righteous qi. Therefore, whether tonifying or purging, one must be aware of the corresponding negative effects.
Many TCM enthusiasts who are unwilling to study systematically often do not recognize the properties of herbs or understand differentiation of syndromes. In the absence of a comprehensive grasp of the body’s deficiency and excess states, they often only see one aspect of deficiency and overlook other aspects of excess, leading to one-sided medication and committing the errors of deficiency deficiency and excess excess, resulting in severe consequences.
In the late stage of illness, it is not the same; treatment does not adhere to the four seasons, does not understand the sun and moon, does not examine the reverse and the following, the disease form has already formed, and then wishes to use fine needles externally and decoctions internally, coarse methods are dangerous, thinking they can attack, thus the disease does not resolve, and new diseases arise.“Suwen – Treatise on the Transformation of Essence and Qi”
This article is sourced from the Guangming TCM textbook “Introduction to TCM Concepts”. If there is any infringement, please contact for removal!