Xu (虚) and Shi (实) refer to the nature of pathological changes and are extremely important in differential diagnosis.
Thus, Xu indicates supplementation, while Shi indicates purging, which are essential methods for diagnosis and treatment; supplementation leads to Shi, and purging leads to Xu, which are the inevitable results of accurate diagnosis and treatment. However, understanding the Xu and Shi of pathological changes and the methods of supplementation and purging is relatively easy at a superficial level, but achieving precise differentiation and application is quite challenging.
Based on literature review and clinical experience, the meanings of Xu and Shi are compiled as follows for research purposes, which may assist in differential diagnosis and treatment.
When analyzing the Xu and Shi of pathological changes during diagnosis, there are various meanings that should not be confused, as this would affect the accuracy of the diagnosis. Upon detailed analysis, there are approximately the following categories:
1. Differentiation of Xu and Shi based on the strength of Zheng Qi (正气)
In the “Shang Han Lun” (伤寒论), it states: “When the pulse is rapid on arrival and slow on departure, it is called internal Xu and external Shi. When the pulse is slow on arrival and rapid on departure, it is called internal Shi and external Xu.”
According to Zhou Chengzhi in the “Bian Ping Mai Zhang Ju” (辨平脉章句), it is explained that: “The arrival and departure refer to the pulse’s entry and exit; entry and exit refer to the internal and external aspects of Yin, Yang, blood, and Qi. Rapid arrival and slow departure indicate more exit than entry, thus Qi accumulates externally, hence external Shi. Slow arrival and rapid departure indicate more entry than exit, thus Qi accumulates internally, hence internal Shi. External Shi indicates weak Yin absorption, hence internal Xu; internal Shi indicates weak Yang propulsion, hence external Xu.”
The entry and exit of pulse Qi, whether Yin or Yang, all belong to the category of Zheng Qi. Therefore, the Xu and Shi mentioned here refer to Zheng Qi and do not include Xie Qi (邪气).
2. Differentiation of Xu and Shi based on the strength of Xie Qi (邪气)
The “Suwen” (素问) states: “When Xie Qi is strong, it is Shi; when vital essence is depleted, it is Xu.”
Zhang Zhizong in the “Suwen Jizhu” (素问集注) explains: “Xie Qi includes the evils of wind, cold, heat, and dampness, while vital essence refers to Ying Qi (营气) and Wei Qi (卫气). Since Xie Qi can be strong or weak, when Xie Qi is strong, it is Shi; since Zheng Qi can be strong or weak, when vital essence is depleted, it is Xu. Depletion means loss, which may be due to Xie Qi’s invasion.”
Japanese scholar Tanba Genkan in the “Suwen Shi” (素问识) states: “When Xie Qi invades the body, it must first take advantage of the weakness of vital essence to enter. If it enters and vital essence is strong, both will be strong, resulting in Shi, such as in the case of a strong cold stomach condition. If Xie Qi enters and vital essence cannot resist it, it is taken by Xie Qi, resulting in Xu, such as in the case of a direct cold condition.”
Whenever Xie Qi is present, regardless of its strength, it is considered a Shi condition; whenever there is no Xie Qi present, it is merely a deficiency of vital essence, regardless of whether it pertains to Qi or blood, in the organs or bowels, it is considered a Xu condition.
This concept is widely applied in clinical practice.
3. Differentiation of Xu and Shi based on the presence or absence of disease
There are two situations regarding the differentiation of disease and non-disease.
First, disease is considered Shi, while non-disease is considered Xu.
As stated in the “Nanjing” (难经): “External pain and internal comfort indicate external Shi and internal Xu; internal pain and external comfort indicate internal Shi and external Xu.”
When Xie Qi is present externally, it causes external pain, indicating that Xie Qi is at the surface. For example, in conditions treated with Gui Zhi Tang (桂枝汤) or Ma Huang Tang (麻黄汤), one may only see symptoms such as chills, fever, and body aches, which are external manifestations. Since the pathogenic factor has not penetrated internally, the internal aspect is comfortable and not suffering.
When the pathogenic factor is external, it is termed external Shi, and since there is no internal suffering, it is termed internal Xu, which is in contrast to external Shi; when the pathogenic factor occurs internally and causes internal pain, regardless of whether it is cold or heat, it is termed internal Shi based on the location of the pathogenic factor; since the pathogenic factor is not external, there is no external suffering, hence it is termed external Xu.
Thus, Shi indicates disease, while Xu indicates non-disease, which is also a contrasting meaning.
Second, disease is considered Xu, while non-disease is considered Shi.
As stated in the “Nanjing”: “Yang deficiency and Yin excess lead to sweating and recovery; purging leads to death; Yang excess and Yin deficiency lead to sweating and death; purging leads to recovery.”
Hua Shou explains: “Being affected by disease is Xu, while being unaffected is Shi. Only when it is Xu can the pathogenic factor invade; only when it is Shi can the pathogenic factor not enter. This refers to the concept of exterior disease harmonizing with interior disease, and vice versa, particularly in the case of cold transmission changes. When exterior disease harmonizes with interior disease, sweating can be used to resolve the exterior; however, if purging is applied, it harms the unillnessed Zheng Qi and causes the exterior pathogenic factor to penetrate deeply into the interior, thus it is said to lead to death.
Yang excess indicates that Zheng Qi is abundant externally and the exterior is not diseased; Yin deficiency indicates that vital essence is deficient internally and Xie Qi is strong in the organs. Since Xie Qi is strong in the organs, purging leads to recovery; however, if sweating is induced, it may harm the exterior Yang, leading to both exterior and interior deficiency, thus Xie Qi becomes more solidified and cannot be resolved, hence it is also said to lead to death.
Thus, this Xu and Shi are interchangeable terms for disease and non-disease, which is contrary to the meaning in the “Forty-Eighth Difficulties”.
4. Differentiation of Xu and Shi based on the severity of disease
Generally, milder diseases are considered Xu, while more severe diseases are considered Shi.
The differentiation between the major and minor chest-accumulation syndromes in the “Shang Han Lun” belongs to this category.
In the “Shang Han Lun”, it states: “In the case of cold damage for six or seven days, if there is a hard stone-like pain in the heart area upon palpation, it is a major chest-accumulation syndrome; if there is pain in the heart area upon palpation, with a floating and slippery pulse, it is a minor chest-accumulation syndrome.”
The chest-accumulation syndrome is a condition where Yang heat and Shi evil accumulate in the chest, hence it is called “chest-accumulation heat Shi.”
If the heat evil is strong and deeply accumulated, it is termed major chest-accumulation, thus using Da Huang (大黄), Mang Xiao (芒硝), and Gan Sui (甘遂) to purge the heat Shi; if the heat evil is mild and shallowly accumulated, it is termed minor chest-accumulation syndrome, thus using Huang Lian (黄连), Ban Xia (半夏), and Gua Lou (瓜蒌) to clear heat and disperse the accumulation.
Although there are differences in severity, they are both considered heat Shi conditions.
The Xie Xin Tang (泻心汤) syndrome, which is a Xu condition, is due to the prior deficiency of Yang Qi in the middle burner and the internal invasion of formless heat evil, thus the various formulations of Ban Xia Xie Xin Tang (半夏泻心汤), Sheng Jiang Xie Xin Tang (生姜泻心汤), and Gan Cao Xie Xin Tang (甘草泻心汤) differ in treatment but all use Ren Shen (人参), Da Zao (大枣), Gan Jiang (干姜), and Gan Cao (甘草) to warm and tonify the Yang Qi of the middle burner as a base, supplemented with Huang Qin (黄芩) and Huang Lian (黄连) to clear the formless heat evil that has invaded internally, thus the accumulation syndrome is fundamentally a Xu condition.
The “Shang Han Lun” states: “If the disease arises from Yang and purging is applied, heat will enter and cause chest-accumulation; if the disease arises from Yin and purging is applied, it will cause accumulation.”
Thus, the chest-accumulation syndrome is termed “chest-accumulation heat Shi“, while the accumulation syndrome is termed: “This is not heat Shi, but due to deficiency in the stomach, causing Qi to rise and harden, hence it is termed hard.” This indicates that the heat in the chest-accumulation is severe, thus it is a Shi condition, while the accumulation in the heart area is mild, thus it is a Xu condition.
5. Differentiation of Xu and Shi based on cold and heatFirst, cold is considered Xu, while heat is considered Shi.
The “Suwen” states: “Yang is Shi, while Yin is Xu“, which carries such meaning. Tanba Genkan in the “Yao Zhi Tong Yi” (药治通义) states: “Cold leading to diarrhea is widely recognized as a major Xu condition that requires supplementation; tidal heat and delirium are widely recognized as a major Shi condition that requires purging.”
The former is a Xu cold condition, while the latter is a Shi heat condition.
Secondly, cold is considered Yin Shi and Yang Xu, while heat is considered Yang Shi and Yin Xu.
The “Suwen” states: “When Yin is excessive, it leads to internal cold; when Yang is deficient, it leads to external cold”; this belongs to the former; “When Yang is excessive, it leads to external heat; when Yin is deficient, it leads to internal heat”; this belongs to the latter. These are all oppositional meanings of Yin and Yang.
6. Differentiation of Xu and Shi based on the form of disease
This mainly refers to the accumulation, dispersion, emptiness, and hardness of the disease.
For example, Qi stagnation upwards is Shi, while downward sinking is Xu; Qi accumulation internally is Shi, while external dispersion is Xu.
7. Differentiation of Xu and Shi based on wind evil
The “Ling Shu” (灵枢) states: “Wind that comes from its native place is Shi wind, which promotes growth and nourishes all things; wind that comes from the opposing direction is Xu wind, which harms people and is deadly. One should be cautious of Xu wind and avoid it.”
Zhang Jiebin explains: “The native place refers to the place where Tai Yi resides. For example, when the moon is in the Rat position, the wind comes from the north, which is the correct winter Qi; when the moon is in the Rabbit position, the wind comes from the east, which is the correct spring Qi; when the moon is in the Horse position, the wind comes from the south, which is the correct summer Qi; when the moon is in the Rooster position, the wind comes from the west, which is the correct autumn Qi. The four corners and twelve positions all have such Qi.”
When Qi is in its correct position, Zheng Qi is abundant, hence it is termed Shi wind, which can promote growth and nourish all things. When Qi is lost from its correct position, Zheng Qi is insufficient, hence it is termed Xu wind, which can harm people and is deadly, thus it should be avoided.” (“Liu Jing: Nine Palaces and Eight Winds” annotation, Volume 27)
In the “Neijing” (内经), Xu wind and Shi wind are also referred to as “Xu evil and Zheng evil”; for example, the “Ling Shu” states: “Xu evil is within the body, causing sweating and movement; Zheng evil is within the person, causing subtle changes…”
Based on the above analysis, the meanings of Xu and Shi in Traditional Chinese Medicine are extensive and encompass multiple aspects.
Within Zheng Qi, there are both Xu and Shi, and within Xie Qi, there are also both Xu and Shi. Therefore, in pathological changes and syndromes, there are always Xu and Shi. Simply relying on the phrase from the “Tong Ping Xu Shi Lun” (通评虚实论) “When Xie Qi is strong, it is Shi; when vital essence is depleted, it is Xu” cannot encompass the full scope of Xu and Shi.
Note: This article was published in the “Selected Lectures on Traditional Chinese Medicine, Volume 1”
The article is sourced from the internet
Reposted from: Yipin Pavilion
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