闻之津液渗泄之所曰腠。纹理缝会之中曰理。腠者是三焦通会元真之处。理者是皮肤脏腑之纹理也。
字书谓肤肉之间为腠理。以其有脉理焉。三说合观。体用备矣。考之内经。则曰开、曰阖、曰粗、曰细。曰疏、曰
密。有因天者。有因人者。有因腑而异者。有因病而异者。因天者何。热则人气在外。皮肤缓。腠理开。汗大泄。
血气减。皮淖泽。寒则人气在中。皮肤致。腠理闭。汗不出。血气强。肉坚涩。此腠理之开闭。因天之寒暑也。因
人者何。膏者其肉淖。而粗理者身寒。细理者身热。脂者其肉坚。细理者热。粗理者寒。此腠理之粗细。因人
之脂膏也。何谓因腑而异。三焦膀胱者。腠理毫毛其应。密理浓皮者。三焦膀胱浓。粗理薄皮者。三焦膀胱
薄。疏腠理者。三焦膀胱缓。皮急而无毫毛者。三焦膀胱急。毫毛美而疏者。三焦膀胱直。稀毫毛者。三焦膀
胱结。此腠理之疏密。因腑而异者也。何谓因病而异。阳胜则身热。腠理闭。喘粗为之俯仰。汗不出而热。齿
干以烦冤。腹满死。能冬不能夏。阴胜则身寒。汗出身常清。数栗而寒。寒则厥。厥则腹满死。能夏不能冬。此
阴阳更胜之变。病之形能也。然阳病亦有汗出者。阴病亦有不汗出者。其开也卫气虚。其闭也卫气实。是
又因证而异。可与诊汗之法参观也。要之。开则有汗。闭则无汗。察腠理之开闭。视汗液之有无一也。此腠
理之开闭。因病而异者也。盖观粗细与疏密者。欲明其体。而观开阖之常变者。欲达其用也。且夫腠理之
开阖。非腠理之自为开阖也。有温分肉。充皮肤。肥腠理。司开阖者焉。盖卫气也。卫气者。下焦之所出。太阴
主其内。太阳主其外者也。阴平阳秘。卫气和矣。卫气和。则分肉解利。皮肤调柔。腠理致密矣。如是而云开
阖。则似开非开。似阖非阖。然非不开也。非不阖也。有时而开。有时而阖。或因寒暑。或因冷暖。或因动静。非
病也。常也。时开则开。时阖则阖者也。设或不当开而开。不当阖而阖。岂得谓之无病哉。合汗而诊之。因时
而验之。参证而辨之。知其开阖之常。即知其开阖之变矣。经曰。谨察卫气。为百病母。腠理之开阖。卫气之
虚实也。开阖虚实。盖可以忽乎哉。
It is heard that the place where body fluids (Jinye, 津液) seep and excrete is called "Cou" (Cou, 腠). The place where textures and seams meet is called "Li" (Li, 理). "Cou" is the place where the Sanjiao (Triple Burner, 三焦) connects and gathers Yuanzhen (Original True Qi, 元真). "Li" refers to the textures of the skin and Zang-Fu organs.
Dictionaries define the space between skin and flesh as "Coul i" (Couli, 腠理), because there are vein textures therein. Observing these three explanations together, both its substance (Ti, 体) and function (Yong, 用) are complete. Examining the *Neijing* (Inner Canon, 《内经》), it mentions "opening" (Kai, 开), "closing" (He, 阖), "coarse" (Cu, 粗), "fine" (Xi, 细), "sparse" (Shu, 疏), and "dense" (Mi, 密). Some vary due to heaven (environmental climate), some due to human constitution, some differ by Fu organs, and some differ by disease patterns.
What does it mean to vary due to heaven? When hot, human qi moves outward; the skin relaxes, Couli opens, sweat pours out profusely, blood and qi diminish, and the skin becomes moist and lustrous. When cold, human qi stays inward; the skin becomes dense, Couli closes, sweat does not exit, blood and qi become strong, and muscles become firm and stiff. This is how the opening and closing of Couli vary with the cold and heat of heaven.
What does it mean to vary due to human constitution? Those with a "Gao" (Pasty/Fatty, 膏) constitution have soft flesh; if their texture is coarse, they feel cold; if fine, they feel hot. Those with a "Zhi" (Lean/Firm, 脂) constitution have firm flesh; if their texture is fine, they feel hot; if coarse, they feel cold. This is how the coarseness and fineness of Couli depend on one's fatty or lean constitution.
What does it mean to differ by Fu organs? The Sanjiao (Triple Burner, 三焦) and Bladder (Pangguang, 膀胱) correspond to Couli and body hair. Those with dense textures and thick skin have robust Sanjiao and Bladder functions; those with coarse textures and thin skin have weak Sanjiao and Bladder functions. Those with sparse Couli have relaxed Sanjiao and Bladder functions; those with tight skin lacking body hair have constrained Sanjiao and Bladder functions; those with beautiful and sparse body hair have upright Sanjiao and Bladder functions; those with scarce body hair have knotted/stagnant Sanjiao and Bladder functions. This is how the sparsity and density of Couli differ according to the state of the Fu organs.
What does it mean to differ by disease patterns? Yang excess leads to body heat, closed Couli, rapid and rough breathing causing the body to heave, no sweat but fever, dry teeth, and vexation/oppression. If abdominal fullness occurs, death ensues; such patients can tolerate winter but not summer. Yin excess leads to body cold, sweating with constant chilliness, frequent shivering and cold, cold extremities leading to Jue (Cold Reversal, 厥), and if abdominal fullness accompanies Jue, death ensues; such patients can tolerate summer but not winter. These are variations in the alternating dominance of Yin and Yang, representing the form and capacity of diseases. However, Yang diseases may also present with sweating, and Yin diseases may present without sweating. Opening occurs when Wei Qi (Defensive Qi, 卫气) is deficient; closing occurs when Wei Qi is solid. This again varies by syndrome and can be observed alongside methods for diagnosing sweat. In summary, opening implies sweat; closing implies no sweat. Observing the opening and closing of Couli is equivalent to viewing the presence or absence of sweat. This is how the opening and closing of Couli differ by disease.
Generally, observing coarseness and fineness aims to understand its substance, while observing the normality and variation of opening and closing aims to grasp its function. Moreover, the opening and closing of Couli do not occur autonomously by Couli itself, but are governed by something that warms the muscle intervals, nourishes the skin, plumps the Couli, and controls opening and closing—namely, Wei Qi (Defensive Qi, 卫气). Wei Qi originates from the Lower Jiao (Lower Burner, 下焦), is primarily managed internally by the Taiyin (Taiyin Lung/Spleen channel, 太阴), and externally by the Taiyang (Taiyang Bladder/Large Intestine channel, 太阳). When Yin is peaceful and Yang is secure, Wei Qi is harmonious. When Wei Qi is harmonious, muscle intervals are smooth, skin is supple, and Couli is dense. In such a state, what is called opening and closing is neither truly open nor truly closed, yet it is not entirely unopen or unclosed; rather, it opens at times and closes at times. This may be due to cold/heat, warmth/chill, or movement/stillness. This is not disease, but normalcy: opening when it should, closing when it should. If it opens when it should not, or closes when it should not, how can one say there is no disease? By combining sweat diagnosis, verifying by time, and differentiating by symptoms, knowing the normal pattern of opening and closing allows one to know its variations. The Classics state: "Carefully observe Wei Qi, for it is the mother of all diseases." The opening and closing of Couli reflect the deficiency and excess of Wei Qi. Can the deficiency and excess of opening and closing be ignored?