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In the Han Dynasty, Zhang Zhongjing, the Grand Commandant, wrote the book "Shanghan" (Treatise on Cold Damage), establishing 113 formulas and 397 methods. These are applied flexibly according to the changes of the disease, undergoing thousands of transformations with infinite subtlety. All diseases should take this as a standard and should not be read merely as a book treating cold damage. However, later commentators on this book, numbering over fifty, shifted chapters around and criticized each other, yet no definitive conclusion was reached. I maintain: This book should be viewed in two major sections. The first section is for exterior cold syndromes, and the latter section is for interior cold syndromes. Interior cold may result from external pathogens directly invading the interior, or it may arise internally due to deficiency, leading to cold generation. In essence, it does not go beyond Spleen and Kidney Yang Deficiency. When Yang is deficient, not only can it not resist cold, but Spleen Yang deficiency fails to distribute essential substances, and Kidney Yang deficiency fails to transport fluids. Since essential substances cannot be distributed and fluids cannot be transported, dampness is generated frequently, while fire is generated rarely. Although its methods are divided into the Six Channels, they do not go beyond the scope of the San Jiao (Triple Burner). Speaking of the Six Channels clarifies the gates through which pathogens enter, the pathways they travel, and the origins and transmission of the disease; speaking of the San Jiao emphasizes that有形 phlegm-fluids, water-dampness, and dregs are bound by pathogens, forming the disease. Observing his discussions, he mentions the chest center, heart center, below the heart, hypochondrium, stomach center, abdomen, and lower abdomen. Although he does not explicitly mention the San Jiao, his description is more detailed than that of those who speak of the San Jiao. The human body is a small heaven and earth. Above the diaphragm, Heaven Qi dominates, corresponding to the Lung and Heart. Below the diaphragm, Earth Qi dominates, corresponding to the Spleen, Stomach, large and small intestines, Bladder, San Jiao, and Kidney. Between heaven and earth lies the diaphragm, which is the region of the Liver and Gallbladder, like trees on the earth. Running inside the muscles and outside the bones and sinews, the meridians and collaterals circulate blood and vessels, like the veins and channels on earth that connect with Heaven Qi. From below the diaphragm upwards to the chest, and sideways to the hypochondrium, these are places where clear Qi and body fluids circulate. Pathologies here do not go beyond phlegm-fluids and water-dampness being struck and bound by pathogens, knotting with Qi. From the epigastrium and abdomen down to the lower abdomen, there are dregs and turbid substances where pathogens can attach, forming excess syndromes in the lower jiao. One is clear Yang, the other is turbid Yin; thus the human body is called a small heaven and earth. Observing the formulas and methods established by Master Zhang Zhongjing, they indeed treat the heaven and earth of the human body harmed by pathogens. The Six Channels are accurate to the finest detail, and the San Jiao is precise within inches. Who else but Zhongjing deserves the title of Medical Sage of the ages?

Taking Taiyang Disease as an example, the Taiyang meridian runs along the back. The back is the mansion of the chest, and the chest is the outer casing of the Lung. The Lung governs the skin and hair. Whenever pathogens enter via the Taiyang channel, they must start from the pores. Moreover, the Qi of all six channels is circulated by Heaven Qi; if the meridian Qi is stagnant, Heaven Qi must also be stagnant. Thus, the *Shanghan Lun* states: In Taiyang disease, there is headache, fever, body pain, lower back pain, joint pain, aversion to wind, absence of sweating, and wheezing. It also says: Wheezing with chest fullness; in severe cases, nosebleed occurs, and the disease resolves after bleeding. The symptoms listed above are all manifestations of Taiyang; wheezing and chest fullness indicate pathogen obstruction causing Lung Qi stagnation. Nosebleed occurs because cold-dryness transforms into heat, and excessive heat moves blood, which exits through the clear passages of the Lung. Resolution via nosebleed is the same as resolution via sweating, hence it is said that the disease resolves after bleeding. The scripture discusses Taiyang, clearly also discussing the Lung. Furthermore, pathogens move from skin and hair to muscles, and from muscles to meridians, getting closer layer by layer; this is horizontal entry. Since pathogens enter horizontally from the exterior, medicines must push horizontally from the interior. Therefore, the light and empty *Mahuang Tang* (Ephedra Decoction) is used to transform sweat from the Lung and reach the skin and hair externally, exiting through the Lung's apertures, thereby opening the gate of Taiyang (The scripture says: Light substances can remove excess. Also: Thin flavors cause excretion, thick flavors cause heat generation. Mahuang has an extremely hollow constitution and thin flavor and aroma; it is light, floating, upward-moving, hollow, and outward-reaching. Taiyang medicine is Lung medicine; thus, it is used as the Sovereign herb and also as the Envoy. Guizhi is pungent, warm, and slightly moist, primarily warming the muscles; its branches also extend horizontally, so it serves as the Minister. Xingren is moist in texture, slightly pungent and bitter, with bitterness outweighing pungency; it opens and descends, and since kernels contain life force, it can enter the Heart to transform sweat. Zhi Gancao is slightly moist and sweet, capable of moderating drug action in the upper part, so it serves as the Assistant. Although the formula contains only four herbs, its spirit is infinitely subtle. Regrettably, later generations abandoned it and instead used pungent, drying, turbid, and fierce substances such as Qianghuo, Duhuo, Jingjie, and Bohe, unaware that thick flavors generate heat, and their use merely increases irritability. Moreover, Mahuang opens and exerts horizontal force; Qianghuo and Duhuo ascend and exert vertical force. The Lung governs Heaven Qi, which should open and descend, but not ascend. Therefore, although Qianghuo and Duhuo existed in the *Shennong Bencao Jing*, they were not intended for treating Shanghan or Wenbing, which is why Zhongjing did not use them). If sweating is attempted but no sweat appears, accompanied by irritability, this indicates pathogen stagnation generating heat, internally scorching Lung fluids. Use *Da Qinglong Tang* (Major Blue Dragon Decoction), resolving with pungent-cool and moistening properties. (*Da Qinglong Tang* adds Shigao, Shengjiang, and Dazao to *Mahuang Tang*. The combination of Mahuang, Shengjiang, and Shigao is extremely subtle. The name "Qinglong" refers to the dragon as a water creature, symbolizing the movement of fluids and generation of sweat). If exterior pathogens remain unresolved, binding damp-heat in the interior and manifesting as jaundice on the skin, use *Mahuang Lianqiao Chixiaodou Shengzipi Tang* (Ephedra, Forsythia and Adzuki Bean Decoction with Catalpa Bark), resolving with pungent-cool and drying properties. If after sweating, there is sweating with wheezing, or wheezing due to excessive drinking, this indicates that although exterior pathogens have resolved, some remain, and residual pathogens in the Lung bind with water pathogens. Therefore, use *Maxing Gan Shi Tang* (Ephedra, Apricot Kernel, Licorice and Gypsum Decoction), resolving the exterior with pungent-cool properties; once the exterior is resolved, water pathogens will naturally exit with sweat. If water retention is severe, with fever and unresolved exterior, fluid accumulation below the heart, dry retching, coughing, wheezing, choking, thirst, or no thirst, or normal bowel movements, or difficult urination—all signs of water retention—use *Xiao Qinglong Tang* (Minor Blue Dragon Decoction) as the primary treatment. (Mahuang and Guizhi open the exterior; Shaoyao and Gancao protect the Ying level. Particularly wonderful is the pungent-moistening fluid-moving action of Xixin, the pungent-smooth descending action of Banxia, and the combined use of Ganjiang and Wuweizi to warm Lung Yang and secure Lung Yin, leaving no detail unaddressed; truly a divine formula. The modifications under the formula match the syndrome perfectly. For mild diarrhea, remove Mahuang and add Yuanhua; for thirst, remove Banxia and add Gualougen; for difficult urination and lower abdominal fullness, remove Mahuang and add Fuling; for wheezing, remove Mahuang and add Xingren; if cold water was mistakenly drunk, causing profuse sweating and binding of cold-water, resulting in choking, remove Mahuang and add Fuzi). Sweat belongs to the category of water, and the Lung is the source of water. If sweat does not resolve, pathogens bind Lung Qi, preventing the regulation of water passages and downward transmission to the Bladder, causing water to stagnate between the Lung and Stomach. If the exterior is not opened and only diuretics are used, the binding cannot be resolved; if only the exterior is opened without using pungent substances to move water, the water pathogens cannot be dispelled. This formula contains descent within ascent and closure within opening, truly unpredictable like a divine dragon; how could later generations dream of it? The treatise states: If the condition resembles Guizhi Syndrome but without headache or neck stiffness, with a faintly floating pulse at the cun position, or a suddenly tight pulse, or cold hands and feet, hardness and stuffiness in the chest, Qi rushing up to the throat, and difficulty breathing, this indicates cold-fluid in the chest, requiring emesis (provoked by the medicine), suitable for *Gua Di San* (Melon Stalk Powder). The so-called "cold" refers to cold-fluid. Observing the *Shennong Bencao Jing*, one can see that Gua Di and Chixiaodou can induce vomiting to expel water pathogens from the chest and abdomen. After sweating, emesis, or purging, if Zheng Qi fails to circulate, phlegm-fluid and knotted Qi remain between the heart and chest, disturbing clear Yang, causing vexation and insomnia. In severe cases, restlessness and inner agitation occur; use *Zhizi Chi Tang* (Gardenia and Fermented Soybean Decoction) to induce emesis. (After taking the medicine, provoke vomiting. Zhizi is light, empty, and floating, slightly bitter and clearing heat; Dou Chi is steamed, sun-dried, and fermented, thus able to ventilate accumulated phlegm-fluid and knotted Qi). If there is inner agitation, hunger but inability to eat, and only sweating on the head (Yang pathogen above, wanting to exit but unable), or vexation-heat with sweating, chest oppression, chest fullness with wheezing, or knotted pain in the heart, all are treated with *Zhizi Chi Tang* to ventilate and transform, without provoking vomiting, because sweating has already occurred. Other variations include: Vomiting—*Zhizi Shengjiang Tang*; Deficiency—*Zhizi Gancao Tang*; Mild vexation after mistaken purging—*Zhizi Ganjiang Tang*; Damp-heat jaundice—*Zhizi Bopi Tang*; Vexation and abdominal fullness with restlessness after purging—*Zhizi Houpo Zhishi Tang*; Food recurrence—*Zhishi Zhichi Tang*; With retained food, add Dahuang the size of a chess piece. (These two formulas treat both the heart center and the abdomen). Observing the formulas following *Maxing Gan Shi Tang*, they all treat water-fluid, phlegm-fluid, and knotted Qi in the chest and heart center. This is what is meant by "the Six Channels do not go beyond the San Jiao," and this is what is meant by "cold-dryness binding dampness." But this is not all. There are also cases of fever persisting for six or seven days without resolution, accompanied by vexation, thirst for water, and vomiting after drinking, named Water Reversal. This indicates unresolved exterior pathogens and internal water retention. The patient lacks aversion-to-cold signs, distinguishing it from *Xiao Qinglong Tang* syndrome. However, since fever persists, it must be treated concurrently. Use *Wu Ling San* (Poria Pill) as the primary treatment. Drink plenty of warm water; recovery comes with sweating. The formula uses Guizhi to transform Bladder Qi and release the muscle layer, achieving two effects with one herb. Other cases: After sweating, water stagnates in the chest without descending, causing vexation-thirst and difficult urination; or after mistaken purging, epigastric fullness, dry mouth, vexation-thirst, and difficult urination; or when a disease requiring sweating is instead bathed in cold water, causing water-Qi to knot in the skin and muscles, resulting in gooseflesh and a desire to drink (the phrase "desire to drink" implies wanting to drink but not actually drinking), yet paradoxically no thirst. In all these cases, *Wu Ling San* is used to guide chest water pathogens out via urination. If Yangming disease presents with fever and thirst for water, use *Zhu Ling Tang* (Polyporus Decoction). Here, Guizhi from *Wu Ling San* is not used for releasing the exterior and transforming Qi, but rather Ejiao and Huashi from *Zhu Ling Tang* are used to moisten dryness and clear heat. (Zhu Ling, Fuling, Zexie, Huashi, Ejiao). If Shaoyin disease presents with diarrhea, coughing, vomiting, vexation, and insomnia (signs of water retention), use *Wen Ge San* (Clam Shell Powder) to guide damp-heat from below the heart out via urination. Wen Ge dries dampness, clears heat, and nourishes Yin, achieving three benefits at once. Cases with sweating but no thirst indicate water pathogens overflowing externally; cold limbs with palpitations below the heart indicate water pathogens overwhelming the Heart. Both are treated with *Fuling Gancao Tang* (Poria and Licorice Decoction) to suppress and direct water pathogens downward. Otherwise, excessive sweating leads to loss of Yang, and water entering the Stomach from below the heart causes diarrhea. All these treat Bladder Fu pathogens. The Bladder is the lowest Fu organ; when cold-dryness binds dampness and pathology manifests above the diaphragm, it is as described above.

Regarding Wind Strike of Taiyang ("Zhong" means injury), there is another explanation. Wind Strike of Taiyang is wind among cold, attacking only the muscles via the pores. Although it enters through the gates of Taiyang (acupoints) and Taiyin (pores), it has not entered the meridians. Manifestations include nasal congestion and dry retching. Lung Qi is injured but not severely obstructed, resulting in a pulse that is floating at the Yang position (cun) and weak at the Yin position (chi). Floating Yang indicates spontaneous heat; weak Yin indicates spontaneous sweating. There is slight aversion to cold and wind (aversion to wind always accompanies aversion to cold, but it is mild, unlike in Shanghan or Yin channel diseases). There is mild fever ("Xi Xi" describes the flapping of bird feathers; the external heat sensation is not like the steaming heat of Yangming disease emerging from the interior). This indicates pathogens in the Wei level failing to defend the exterior and protect the Ying level, showing disharmony between Ying and Wei Qi. Wei Qi circulates outside the vessels, warming the muscles and plumping the interstices (Interstices refer to sites of fluid secretion; Li refers to tissue textures). Therefore, *Guizhi Tang* (Cinnamon Twig Decoction) is used, taking Guizhi, Gancao, and Shengjiang to warm the Wei, and Shaoyao, Gancao, and Dazao to protect the Ying. When Ying and Wei harmonize, the disease resolves. After taking the medicine, drink hot millet gruel shortly to assist the medicinal power. Cover warmly to achieve a slight, continuous sweat; do not allow profuse sweating, as the disease will not be cured. Profuse sweating disturbs Ying, and since sweat comes from Ying, the Wei pathogens remain. All methods of releasing the muscle layer should follow this principle, differing from sweating methods for Shanghan and from methods bringing pathogens from the interior to the exterior in Wenbing. If sweating is excessive, leading to uncontrollable leakage, with aversion to wind, difficult urination, slight stiffness of the four limbs making flexion and extension difficult (due to fluid depletion), this indicates unresolved exterior pathogens in the Wei level and signs of fluid loss and Yang deficiency. Use *Guizhi Jia Fuzi Tang* (Cinnamon Twig Decoction with Processed Aconite Root) to disperse Wei, protect Ying, restore Yang, and stop sweating. If moxibustion or heated needles are used to induce sweating, and the needle site is exposed to cold, developing red nodules, "Ben Tun" (Gas Attack) will definitely occur, with Qi rushing from the lower abdomen to the chest. To resist cold and transform Bladder Qi. If after purging, the pulse is rapid with chest fullness, indicating middle deficiency with remaining exterior pathogens, use *Guizhi Qu Shaoyao Tang* (Cinnamon Twig Decoction without Paeonia). If after purging, Yang deficiency causes slight aversion to cold, use *Guizhi Qu Shaoyao Jia Fuzi Tang*. If after purging there is mild wheezing, or spontaneous wheezing without purging, this is due to unresolved exterior; use *Guizhi Jia Houpo Xingren Tang* (Cinnamon Twig Decoction with Magnolia Bark and Apricot Kernel) to release the exterior, eliminate phlegm, and descend rebellious Qi. If the Yang pulse is choppy and the Yin pulse is string-taut, there should be acute abdominal pain, indicating Spleen Earth deficiency allowing Liver Wood to invade. First use *Xiao Jianzhong Tang* (Minor Construct the Middle Decoction, i.e., *Guizhi Tang* with Yitang) to use great sweetness to harmonize the Middle Earth. If Spleen deficiency is not corrected, shift to treating Shaoyang with *Xiao Chaihu Tang* (Minor Bupleurum Decoction) to soothe Wood within Earth. If after sweating, body pain persists with a deep, slow pulse, indicating unresolved exterior and existing interior deficiency, use *Guizhi Jia Shaoyao Shengjiang Renshen Tang*. If sweating is excessive, and the person crosses their hands over the heart, experiencing palpitations below the heart and a desire to press, since sweat is the fluid of the Heart, excessive sweating depletes Heart Qi. Use *Guizhi Gancao Tang* (Cinnamon Twig and Licorice Decoction). If the person has aversion to cold and trembles as if wanting to fall to the ground, Yang deficiency is extreme, failing to control water; only *Zhenwu Tang* (True Warrior Decoction) will suffice. If after sweating, palpitations below the navel indicate impending Ben Tun; use *Fuling Guizhi Gancao Dazao Tang* (Poria, Cinnamon Twig, Licorice and Jujube Decoction) to transform Bladder Qi and suppress water pathogens. In Taiyang disease lasting eight or nine days, passing the stage without resolution, with alternating fever and chills occurring two or three times a day resembling malaria, but without vomiting (ruling out Shaoyang), with normal bowel movements and no interior heat signs, this indicates residual pathogens. Use *Guima Gehan Tang* (Half Cinnamon Twig and Half Ephedra Decoction) as a light agent to resolve it. If the pulse is faint with aversion to cold, this indicates dual deficiency of Yin and Yang; do not use sweating, emesis, or purging. If the face has a flushed appearance and the body itches, this indicates minor pathogens trapped in the skin, wanting to exit but unable; use this decoction to induce slight sweating. If the itching feels like insects crawling under the skin, this indicates chronic deficiency; do not use it. If after sweating, the condition resembles malaria, recurring twice a day, with minor pathogens unresolved, sweating should resolve it; use *Guizhi Er Mahuang Yi Tang* (Two Parts Cinnamon Twig and One Part Ephedra Decoction) for mild resolution. With fever and chills, where heat predominates over cold, use *Guizhi Er Yuebi Yi Tang* (Two Parts Cinnamon Twig and One Part Yuebi Decoction) for pungent-cool resolution. (*Yuebi Tang*: Mahuang, Shigao, Gancao, Shengjiang, Dazao). After taking *Guizhi Tang*, if headache and neck stiffness persist, with mild fever, absence of sweating, epigastric fullness and mild pain, and difficult urination, this indicates retained fluid; use *Guizhi Qu Gui Jia Ling Zhu Tang* (Cinnamon Twig Decoction without Cinnamon Twig plus Poria and Atractylodes). In Shanghan with a floating pulse, sweating should be induced; if the physician mistakenly uses fire to force sweating, leading to loss of Yang, panic, mania, and restlessness (this is fire forcing Chest Yang, distinct from Yin loss in Shaoyin sweating; thus *Sini Tang* is not used for restoring Yang, but for calming and anchoring), use *Guizhi Qu Shaoyao Jia Shuqi Longgu Muli Jiuxie Tang* (Cinnamon Twig Decoction without Paeonia plus Cladonia, Dragon Bone and Oyster Shell to Rescue from Peril) to calm fright and resolve phlegm. If mistakenly treated with moxibustion, trapping pathogens without an exit, fire Qi rebels upward, and Yin Qi dominates below, causing heaviness and numbness below the waist, this is named Fire Injury. Use *Guizhi Gancao Longmu Tang* (Cinnamon Twig, Licorice, Dragon Bone and Oyster Shell Decoction) to harmonize Yin and suppress rebellion (since there is no phlegm closure in the heart, Shuqi is not used). If a Taiyang syndrome is mistakenly purged, drawing pathogens into Taiyin, causing abdominal fullness and intermittent pain, use *Guizhi Jia Shaoyao Tang* (Cinnamon Twig Decoction with Added Paeonia) to gather Taiyin pathogens. If there is severe pain, it indicates pathogens knotting in Taiyin; use *Guizhi Jia Dahuang Tang* (Cinnamon Twig Decoction with Added Rhubarb) to guide pathogens out to the Yangming Fu organs. All these involve pathogens in the Wei level and muscle interstices, causing various complications due to mistaken sweating, purging, or fire therapy, with exterior pathogens not fully resolved. Thus, they are all modified from *Guizhi Tang* according to the syndrome to correct errors; they are not standard treatments for the channel. If Wei level and muscle interstice pathogens have not entered the Taiyang meridian but are close to it, presenting with aversion to cold, sweating, and stiffness of the neck and back (a posture of stretching the neck due to stiffness), this indicates pathogens have not entered the meridian (so Mahuang cannot be used), but are close to it (so Guizhi alone is insufficient). Use *Guizhi Jia Gegen Tang* (Cinnamon Twig Decoction with Kudzu Root). Gegen is pungent, sweet, and slightly moist, with thin flavor and aroma, stimulating Stomach Qi to ascend and following Guizhi to reach the exterior. If there is no sweating, or in Yangming disease with eye pain, nasal dryness, and insomnia, or in combined Taiyang-Yangming disease with spontaneous diarrhea, use *Gegen Tang* (Kudzu Root Decoction, i.e., *Guizhi Tang* added with Gegen and Mahuang). If there is no diarrhea but vomiting, use *Gegen Jia Banxia Tang* (Kudzu Root Decoction with Added Pinellia). Although *Gegen Tang* contains Mahuang, the emphasis is on Gegen, using it to raise clear Yang from the Stomach to stop diarrhea and to clear heat with its pungent-sweet, cool-moist nature. If Wind Strike of Taiyang is mistakenly purged, leading to persistent diarrhea, rapid pulse, wheezing, and sweating, this indicates unresolved exterior pathogens and heat sinking into the interior. Use *Gegen Huangqin Huanglian Tang* (Kudzu, Scutellaria and Coptis Decoction, containing Gancao) to resolve the exterior with pungent-cool properties and raise clear Yang, while using bitter-cold herbs to enter the intestine, dry dampness, clear heat, and secure Yin. This is a method treating both exterior and interior.

Note: *Guizhi Tang* and *Gegen Tang* harmonize Ying and Wei, and treat Yangming respectively; they are not solely concerned with the Lung. However, treating Yangming also emphasizes the Lung. For example, if (without lower Jiao excess signs), use *Baihu Tang* (White Tiger Decoction: Shigao, Zhimu, Gancao, Jingmi). For deficiency, use *Baihu Jia Renshen Tang*. If after Shanghan resolves, residual heat remains, with emaciation, shortness of breath, and rebellious Qi desiring to vomit, use *Zhuye Shigao Tang* (Bamboo Leaf and Gypsum Decoction, i.e., *Renshen Baihu Tang* without Zhimu, adding Zhuye, Banxia, and Maidong). Baihu corresponds to Metal of the West. Excessive sweating consumes fluids, Yangming fire blazes, and Lung Metal is burned. Only when the tiger roars and wind arises can hyperthermia resolve. This treats the Lung and Stomach as mother and son simultaneously. It emphasizes clearing dryness and saving the Lung, allowing Heaven Qi to descend clearly and purely for recovery.

Between the heaven and earth of the human body lies the diaphragm. Below the diaphragm and in the hypochondrium, the Liver and Gallbladder are located; the Gallbladder belongs to Shaoyang. If Yangming is not treated, pathogens must transmit to Shaoyang; transmitting to Shaoyang causes pathology in the chest and hypochondrium. The chest and hypochondrium are pathways for clear Yang and sites for the ascending and descending of body fluids. When pathogenic heat transmits here, phlegm-fluids and water-dampness must bind with clear Qi (Heat, even when hot, involves cold). Fullness and distress in the chest and hypochondrium, silence and lack of appetite (Wood pathogen attacking Earth), vexation, and frequent retching (Wood Qi rebelling upward), or chest vexation without retching, or thirst (Shaoyang heat pathogen), or no thirst, or difficult urination (retained phlegm-fluids), or coughing (residual fluid in Lung), or palpitations below the heart (phlegm-fluid), or hardness and stuffiness in the hypochondrium (water-fluid binding with Qi), or abdominal pain (Wood depression overcoming Earth), or slight body heat (residual Taiyang pathogens), are primarily treated with *Xiao Chaihu Tang* (Minor Bupleurum Decoction). (Chaihu inherits the Qi of mid-spring, has a slightly pungent taste, thin flavor and aroma, specializes in ascending and reaching the cold-heat knotted Qi in the Shaoyang chest and hypochondrium, and can also vent pathogens in the intestines, so it is used as the Sovereign herb; Banxia and Huangqin provide descending action, and Shengjiang provides pungency; bitter descent and pungent unblocking are most suitable for damp-heat and phlegm-heat; Renshen, Gancao, and Dazao are used as assistants to block the path of pathogens entering the interior when there are no exterior-interior pathogens. If there are slight exterior-interior pathogens, Renshen should not be used,)