‘Xu’ (虚) and ‘Shi’ (实) refer to the nature of pathological changes and are an extremely important aspect of syndrome differentiation.
Therefore, ‘Xu’ indicates supplementation, while ‘Shi’ indicates purging, which are essential methods for differentiation and treatment; supplementation leads to ‘Shi’, while purging leads to ‘Xu’, which are the inevitable results of accurate differentiation 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 syndrome differentiation and treatment reference.
When analyzing the ‘Xu’ and ‘Shi’ of pathological changes during syndrome differentiation, there are various meanings that should not be confused, as this would affect the accuracy of differentiation. Upon detailed analysis, there are approximately the following categories:
01
Distinction of ‘Xu’ and ‘Shi’ based on the strength of Zheng Qi (正气)In the “Shang Han Lun (伤寒论) – Ping Mai Fa (平脉法)”, it states: “When the pulse is taken, if it comes quickly and leaves slowly, it is called ‘internal Xu and external Shi’. If it comes slowly and leaves quickly, it is called ‘internal Shi and external Xu’.” Zhou Chengzhi explains in the “Bian Ping Mai Zhang Ju (辨平脉章句)” that: “The coming and going refer to the pulse’s entry and exit; entry and exit refer to the internal and external aspects of Yin, Yang, blood, and Qi. If it comes quickly and leaves slowly, it indicates more exit and less entry, thus Qi gathers externally, hence ‘external Shi’; if it comes slowly and leaves quickly, it indicates less exit and more entry, thus Qi gathers internally, hence ‘internal Shi’. External Shi indicates weak Yin absorption, hence internal Xu; internal Shi indicates weak Yang propulsion, hence external Xu.”Regardless of whether the Qi is Yin or Yang, it falls under the category of Zheng Qi. Therefore, the ‘Xu’ and ‘Shi’ mentioned here refer to Zheng Qi and do not include Xie Qi (邪气).
02
Distinction of ‘Xu’ and ‘Shi’ based on the strength of Xie Qi (邪气) and weakness of Zheng QiIn the “Su Wen (素问) – Tong Ping Xu Shi Lun (通评虚实论)”, it states: “When Xie Qi is strong, it is ‘Shi’; when vital essence is depleted, it is ‘Xu’.” Zhang Zhizhong explains in the “Su Wen Ji Zhu (素问集注)” that: “Xie Qi refers to 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 slightly strong, it is said that when Xie Qi is strong, it is ‘Shi’; Zheng Qi can be strong or weak, hence when it is depleted, it is ‘Xu’. ‘Deplete’ means to lose, which can be due to the invasion of Xie Qi.” Japanese scholar Tanba Genkan in the “Su Wen 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 Xie and Zheng Qi are strong, resulting in ‘Shi’, such as in the case of ‘Shang Han Wei Jia Shi Zheng’. If Xie Qi invades and vital essence cannot resist it, resulting in the depletion of vital essence, it is ‘Xu’, such as in the case of ‘Shang Han Zhi Zhong Zheng’.”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.
03
Distinction of ‘Xu’ and ‘Shi’ based on the presence or absence of diseaseThere are two situations regarding the distinction of ‘Xu’ and ‘Shi’ based on disease presence.
First, disease is considered ‘Shi’, while absence of disease is considered ‘Xu’As stated in the “Nan Jing (难经) – Si Shi Ba Nan (四十八难)”: “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 invades externally, it causes external pain, which is referred to as Xie Qi invading the exterior. For example, in the case of Gui Zhi Tang (桂枝汤) or Ma Huang Tang (麻黄汤), one may only observe symptoms such as aversion to cold, fever, and body aches, which are external manifestations. Since the pathogenic factor has not penetrated internally, there is no internal suffering, hence it is termed ‘external Shi’ and ‘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 referred to as ‘internal Shi’; 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 absence of disease, which is also a contrasting meaning.
Second, disease is considered ‘Xu’, while absence of disease is considered ‘Shi’
As stated in the “Nan Jing – Wu Shi Ba Nan (五十八难)”: “Yang Xu and Yin Sheng, sweating leads to recovery; purging leads to death; Yang Sheng and Yin Xu, sweating leads to death; purging leads to recovery.”Hua Shou explains that “being affected by disease is ‘Xu’, while not being affected is ‘Sheng’. Only when it is ‘Xu’ can the pathogenic factor invade; only when it is ‘Sheng’ can the pathogenic factor not enter. This refers to the ‘exterior disease and interior harmony’ and ‘interior disease and exterior harmony’, specifically referring to the transmission of Shang Han. When there is exterior disease and interior harmony, sweating can be applied to resolve the exterior; however, if purging is applied, it harms the unillness of Zheng Qi and causes the exterior pathogenic factor to penetrate deeply into the interior, thus it is said to lead to death.When Yang is strong, it indicates that Zheng Qi is abundant externally and the exterior is not ill; when Yin is Xu, it 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 applied, 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 absence of disease, which is contrary to the meaning in the “Si Shi Ba Nan”.
04
Distinction of ‘Xu’ and ‘Shi’ based on the severity of diseaseGenerally, milder diseases are considered ‘Xu’, while more severe diseases are considered ‘Shi’.The differentiation between Da Xian Xiong Tang (大陷胸汤) and Xiao Xian Xiong Tang (小陷胸汤) in the “Shang Han Lun” belongs to this category.The “Shang Han Lun” states: “In cases of Shang Han for six or seven days, if there is a hard mass in the chest with a deep and tight pulse, and pain under the heart upon palpation, it is treated with Da Xian Xiong Tang; if there is a small mass in the chest, located under the heart, with pain upon palpation and a floating and slippery pulse, it is treated with Xiao Xian Xiong Tang.”The ‘Jie Xiong’ syndrome generally belongs to the category of Yang heat and solid evil accumulating in the chest, hence it is called ‘Jie Xiong Re Shi’.If the heat evil is strong and deeply accumulated, it is classified as ‘Da Jie Xiong’, thus Da Huang (大黄), Mang Xiao (芒硝), and Gan Sui (甘遂) are used to purge the heat and solid evil; if the heat evil is mild and accumulated superficially, it is classified as ‘Xiao Xian Xiong’, thus Huang Lian (黄连), Ban Xia (半夏), and Gua Lou Shi (瓜蒌实) are used to clear heat and disperse the accumulation.Although there are differences in severity, they are both classified as heat and solid evil conditions.The Xiao Xie Xin Tang (泻心汤) syndrome is a virtual distension syndrome, resulting from the prior deficiency of Yang Qi in the middle burner and the internal invasion of formless heat evil, thus Xiao Xie Xin Tang, Sheng Jiang (生姜) Xiao Xie Xin Tang, and Gan Cao (甘草) Xiao Xie Xin Tang are used, which differ in their treatments but all utilize Ren Shen (人参), Da Zao (大枣), Gan Jiang (干姜), and Gan Cao as the basis to warm and tonify the Yang Qi of the middle burner, supplemented with Huang Qin (黄芩) and Huang Lian to clear the formless heat evil that has invaded internally, thus the distension syndrome is fundamentally a ‘Xu’ condition.The “Shang Han Lun” states: “If the disease arises from Yang and purging is applied, heat enters and causes Jie Xiong; if the disease arises from Yin and purging is applied, it causes distension.”Thus, Jie Xiong is referred to as ‘Jie Xiong Re Shi’, while the distension syndrome is referred to as: “This is not heat, but due to deficiency in the stomach, causing Qi to reverse upwards, hence it becomes hard,” indicating that the heat in Jie Xiong is severe, thus it is a ‘Shi’ condition, while the heat in distension is mild, thus it is a ‘Xu’ condition.
05
Distinction of ‘Xu’ and ‘Shi’ based on cold and heatInitially, cold is considered ‘Xu’, while heat is considered ‘Shi’.In the “Su Wen – Tai Yin Yang Ming Lun (太阴阳明论)”, it states: “Yang is solid, Yin is empty”, 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 deficiency that requires supplementation; tidal heat and delirium are widely recognized as a major excess that requires purging.”The former is a ‘Xu Han’ condition, while the latter is a ‘Shi Re’ condition.Secondly, cold is considered Yin solid and Yang deficient, while heat is considered Yang solid and Yin deficient.In the “Su Wen – Tiao Jing Lun (调经论)”, it states: “When Yin is strong, it leads to internal cold; when Yang is deficient, it leads to external cold”; this belongs to the former; “When Yang is strong, 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.
06
Distinction of ‘Xu’ and ‘Shi’ based on the form of diseaseThis primarily involves the accumulation, dispersion, emptiness, and hardness of the disease form.For example, Qi stagnation upwards is ‘Shi’, while downward sinking is ‘Xu’; Qi accumulation internally is ‘Shi’, while external dispersion is ‘Xu’.
07
Distinction of ‘Xu’ and ‘Shi’ based on wind evilIn the “Ling Shu (灵枢) – Jiu Gong Ba Feng Pian (九宫八风篇)”, it states: “Wind that comes from its native place is ‘Shi wind’, which promotes and nourishes all things; wind that comes from a clash is ‘Xu wind’, which harms people and is deadly. One should be cautious and avoid ‘Xu wind’.”Zhang Jiebin explains: “The native place refers to the place where Tai Yi resides. For example, when the moon is in the ‘Zi’ position, the wind comes from the north, which is the correct winter Qi; when the moon is in the ‘Mao’ position, the wind comes from the east, which is the correct spring Qi; when the moon is in the ‘Wu’ position, the wind comes from the south, which is the correct summer Qi; when the moon is in the ‘You’ 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 called ‘Shi wind’, which can promote and nourish all things. When Qi is lost from its correct position, Zheng Qi is insufficient, hence it is called ‘Xu wind’, which can harm people and is most to be avoided.” (In the “Liu Jing – Jiu Gong Ba Feng” annotation, volume twenty-seven)‘Xu wind’ and ‘Shi wind’ in the “Nei Jing (内经)” are also referred to as ‘Xu evil’ and ‘Zheng evil’, as stated in the “Ling Shu – Xie Qi Cang Fu Bing Xing Pian (邪气藏府病形篇)”: “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 concept of ‘Xu’ and ‘Shi’ in TCM is extremely broad, encompassing multiple aspects.Within Zheng Qi, there is both ‘Xu’ and ‘Shi’, and within Xie Qi, there is also both ‘Xu’ and ‘Shi’. Therefore, in pathological changes and syndromes, there is always a presence of both ‘Xu’ and ‘Shi’. Simply relying on the two phrases from the “Tong Ping Xu Shi Lun” – “When Xie Qi is strong, it is ‘Shi’; when vital essence is depleted, it is ‘Xu'” – cannot encompass the comprehensive understanding of ‘Xu’ and ‘Shi’.■
【Source: People’s Health Publishing House, “Selected Lectures on TCM, Volume 1″】
