（出程凤雏《慈幼筏》）
帝曰∶人伤于寒，而传为热，何也？岐伯曰∶夫寒盛则生热也。帝曰∶今夫热病者，皆伤寒之类也。小儿八
岁以后，气血充足，经脉完固，伤寒与大人同治。仍自表达里，先皮毛，次肌肉，次筋骨、肠胃，丝毫不爽。
其始也，先从太阳寒水一经，有恶风恶寒，头痛脊强等证。寒郁皮毛，是为在表。脉浮紧无汗为伤寒，麻黄汤发
之，得汗而解；脉浮缓有汗为伤风，以桂枝汤散之，汗止而解。
〔疏〕太阳经在最外一层，故邪入皮毛，即先伤之。皮毛不能传变，由太阳之络脉传入本经，而后内入诸
经也。邪客皮毛，即玄府闭（汗孔也）。人身脏腑之气，无刻不与外气
通，通故和畅；玄府闭则内气不能发泄而生热，非风寒能变热也。此时但发其皮毛，玄府开而邪随汗散矣。麻
黄、桂枝汗皮毛之方，非解中之药也。若表不解，热积而日甚，从本经反而之内，及各经之井荣俞合交会之处，
则热传于他经，而各经并见矣。（经脉所出为井，所溜为荥，所注为俞，所入为合，十二经脉莫不皆然。）
太阳既罢，无头痛恶寒，脉又不浮，为表证罢而在中，乃阳明少阳之间。脉不浮不沉，而在乎肌肉之间，
皮毛之下。然有二焉∶若微洪而长，阳明脉也，外证鼻干不眠，用葛根解肌；脉弦而数，少阳脉也，外证胁痛、
耳聋、口苦，寒热往来，以小柴胡汤和之。盖阳明少阳，不从标本，从乎中治。若有一毫恶寒，邪尚在表，虽
入中，还当兼散邪。
〔疏〕肌肉不能传变，肌肉之中皆经络也。经络谓之中，里则脏腑，表则皮毛。脏腑之气血，惟经络传达；
外邪之壅热，亦惟经络传变。故阳明少阳皆从中治。中者，经病也，非胃与胆病也（阳明属胃，少阳属胆，皆外
之经络受病，非内之胃与胆病也。）经病用和解，必由汗散，然非开发皮毛之法矣。盖邪初客表，经中阴津受伤，
但启其毛窍而汗自通；及热传中经，血液燔灼，窍虽启，而汗为热隔，不能外达。庸工不知，尚用风热之药，
以发其表，益助热而耗阴，汗源干涸，究竟不得汗而毙者多矣。仲景和解只清解热邪，而津液自存，阴汗既充，
涌出肌表，而外邪自然焕散。此养汗以开玄府，与开玄府而出汗者，迥乎不同也。
邪在阳明则解肌，邪在少阳则和解。然病犹未退，既为传里实热，脉不浮而沉，按之筋骨之间，所谓阳明
胃腑病也，与经病不同（阳明经病已罢，至此传入于胸中之胃腑矣。）若脉沉实有力，外证不恶风寒而反恶热，
谵语大渴，六七日不大便，皆肠胃燥实致之，轻则大柴胡汤，重则三承气，大便通而热退矣。
〔疏〕热邪入里，驱出为难，故就大便通
泄，从其近也。得汗而经邪从汗解，非汗为害，而欲驱之也。便矢而腑邪从矢出，非矢为难而欲攻之也（矢与粪
同。）医不察此，但知消克泻下之法，始终禁绝饮食，求一便矢为能事，殊可笑矣！
寒邪直入三阴之经，名曰直中。乃三阳主气衰，无热拒寒也。故初起即手足厥冷，或战栗蜷卧，不渴，或
腹痛呕吐泄泻，或口吐涎沫，面如刀刮，不发热而脉沉迟无力。此不从阳经传入同治之例，更当外证何如。轻
则理中汤，重则姜附汤、四逆汤治之。
〔疏〕伤寒者，由皮毛经络而后入脏腑。初虽恶寒发热，而终为热证，其人必素有火者；直中脏腑，始终
恶寒而并无发热等证，其人必素无火者。一则发表攻里，一则温中散寒，两途判然明白。证有反常者，如发热面
赤烦躁，揭去衣被，饮冷脉大，非阳证乎？然投凉药而死者，何也？内有伏阴也。切其脉，不论浮沉大小，
必指下无力，按之筋骨之间皆然，甚者服一切茶汤及药皆吐，此阴盛格阳，乃白通汤加人尿猪胆汁证。仲景将
传经、直中并论，正谓有阴证似阳，阳证似阴耳。如太阳证头疼发热，当脉浮而反沉，又似少阴矣，故用麻黄附
子细辛汤；少阴证脉沉，应无热而反发热，又似太阳矣，须用甘草干姜附子汤。阴证四肢厥逆，而阳证亦有厥
逆，此四逆汤与四逆散不同也；阴证下利，阳证亦有漏底，此理中汤与黄龙汤不同也。
（出自程凤雏的《慈幼筏》）
黄帝问道：人受寒邪侵袭，随后却转化为热证，这是什么原因？岐伯回答说：寒邪极盛就会化生热象。黄帝说：如今所说的热病，都属于伤寒的范畴。小儿八岁以后，气血充足，经脉坚固完善，治疗伤寒与成人相同。病邪仍然遵循由表入里的规律，先侵犯皮毛，再深入肌肉，接着是筋骨、肠胃，丝毫不差。
起初，病邪先从太阳经（足太阳膀胱经，主一身之表）开始，出现怕风、怕冷、头痛、项背强直等症状。寒邪郁闭在皮毛，这属于表证。脉象浮紧且无汗的，称为伤寒，用麻黄汤发汗治疗，出汗后病愈；脉象浮缓且有汗的，称为伤风，用桂枝汤解肌发表，汗止后病愈。
〔疏〕太阳经位于人体最外层，所以邪气侵入皮毛，首先损伤太阳经。皮毛本身不能传变病邪，而是通过太阳经的络脉传入本经，然后才向内传入其他各经。邪气客居皮毛，导致玄府闭塞（即汗孔）。人体的脏腑之气，无时无刻不与外界之气相通，通畅则和气畅达；玄府闭塞则体内之气不能发泄而化生热，并非风寒直接变成了热。此时只需发散皮毛之邪，玄府打开，邪气随汗液消散。麻黄汤和桂枝汤是发散皮毛之邪的方剂，不是清热解里的药物。如果表证未解，热邪积聚日益加重，从本经反过来内传，以及传到各经的井、荥、俞、合交会之处，那么热邪就传向他经，各经的症状都会出现。（经脉所出为井穴，所溜为荥穴，所注为俞穴，所入为合穴，十二经脉都是如此。）
太阳经的病证解除后，如果没有头痛恶寒，脉象也不浮，说明表证已罢而在半表半里或里，处于阳明经和少阳经之间。脉象不浮不沉，而在肌肉之间，皮毛之下。这里又有两种情况：如果脉象微洪而长，这是阳明经的脉象，外证表现为鼻干、失眠，用葛根汤解肌退热；如果脉象弦而数，这是少阳经的脉象，外证表现为胁痛、耳聋、口苦、寒热往来，用小柴胡汤和解少阳。大概阳明经和少阳经，不从标本论治，而从“中气”论治。如果有一丝一毫的恶寒，说明邪气仍在表，即使已经入里，还应当兼用散邪的方法。
〔疏〕肌肉本身不能传变病邪，肌肉之中遍布经络。经络称为“中”，里指脏腑，表指皮毛。脏腑的气血，依靠经络来传达；外邪壅滞产生的热邪，也依靠经络来传变。所以阳明经和少阳经的病都从中治。所谓“中”，是指经络有病，而不是胃和胆这两个脏腑有病（阳明属胃，少阳属胆，都是外在的经络受病，不是内在的胃与胆有病）。经络有病用和解法，必须通过汗法来疏散，但这已经不是开发皮毛的方法了。大概邪气初客于表，经络中的阴津受伤，只要开启毛窍，汗自然通调；等到热邪传入中经，血液被灼烧，虽然开启了毛窍，但汗被热邪阻隔，不能向外排出。庸医不知道这一点，还使用风热性质的药物来发汗，更加助长热邪并耗伤阴液，导致汗源干涸，最终因无法出汗而死亡的很多。张仲景的和解法只是清解热邪，从而保存津液，阴液充足后，汗液自然涌出肌表，外邪自然散发。这种通过滋养汗源来开启玄府，与强行开启玄府以求出汗的方法，截然不同。
邪气在阳明经就用解肌法，邪气在少阳经就用和解法。然而病仍未退，既然已经传变为里实热证，脉象不浮而沉，按之在筋骨之间，这就是所谓的阳明胃腑病，与经络病不同（阳明经病已罢，至此传入胸中的胃腑了）。如果脉象沉实有力，外证不怕风寒反而怕热，胡言乱语、极度口渴，六七天不大便，这都是肠胃燥实导致的，轻症用大柴胡汤，重症用三承气汤，大便通畅后热势自退。
〔疏〕热邪入里，驱除困难，所以顺着大便通畅泄下的途径，取其就近原则。得到汗出，经络之邪随汗而解，并不是汗液有害而要驱除它。排便，腑中之邪随粪便而出，并不是粪便难排而要攻下它（矢与粪同义）。医生如果不考察这一点，只知道消导攻下的方法，始终禁止饮食，把求得一次排便作为能事，真是可笑！
寒邪直接侵入三阴经，名叫直中。这是因为三阳经的主气衰弱，没有热邪来抗拒寒邪。所以刚发病就手足厥冷，或者战栗蜷卧，口不渴，或者腹痛呕吐泄泻，或者口吐涎沫，面色像刀刮一样苍白，不发热而脉象沉迟无力。这不从阳经传入的同治例子，更应当根据外证如何治疗。轻症用理中汤，重症用姜附汤、四逆汤治疗。
〔疏〕伤寒，是由皮毛经络而后进入脏腑。起初虽然恶寒发热，但最终成为热证，这种人必定素体有火；直中脏腑，始终恶寒而没有发热等证，这种人必定素体无火。一个是发表攻里，一个是温中散寒，两条路径判然分明。如果有反常的证候，比如发热面赤烦躁，掀开衣被，想喝冷水，脉象大，这不是阳证吗？然而投用凉药却死亡的，为什么呢？因为内有伏阴。切其脉，不论浮沉大小，必定指下无力，按至筋骨之间也是如此，严重的服用一切茶汤及药物都会呕吐，这是阴盛格阳，属于白通汤加人尿猪胆汁证的范畴。张仲景将传经和直中一并论述，正是说有阴证似阳，阳证似阴的情况。如太阳病的头疼发热，当脉浮反而沉，又像是少阴病了，所以用麻黄附子细辛汤；少阴病脉沉，应无热反而发热，又像是太阳病了，须用甘草干姜附子汤。阴证四肢厥逆，阳证也有厥逆，这是四逆汤与四逆散不同；阴证下利，阳证也有漏底（完谷不化），这是理中汤与黄龙汤不同。
(From Cheng Fengchu's *Ciyou Fa*)
The Yellow Emperor asked: When humans are injured by cold, why does it subsequently transform into heat? Qibo replied: When cold is excessive, it generates heat. The Yellow Emperor said: Now, all those suffering from heat diseases belong to the category of Shanghan (Cold Damage). After the age of eight, children have sufficient Qi and blood, and their meridians are complete and solid; thus, Shanghan in children is treated the same as in adults. The pathogen still follows the progression from exterior to interior, first affecting the skin and hair, then muscles, followed by sinews and bones, and finally the intestines and stomach, without any error.
Initially, the pathogen enters through the Taiyang meridian (Foot-Taiyang Bladder Meridian, which governs the exterior of the body), presenting with symptoms such as aversion to wind, aversion to cold, headache, and stiffness of the neck and back. Cold stagnating in the skin and hair constitutes an exterior syndrome. A floating and tight pulse without sweating indicates Shanghan (injury by cold), treated with Mahuang Tang (Ephedra Decoction) to induce sweating for resolution; a floating and moderate pulse with sweating indicates Shangfeng (injury by wind), treated with Guizhi Tang (Cinnamon Twig Decoction) to release the muscle layer, resolving when sweating stops.
[Commentary] The Taiyang meridian is located at the outermost layer of the body; therefore, when pathogens invade the skin and hair, they first injure this meridian. The skin and hair themselves cannot transmit the pathogen; rather, it transmits via the collateral vessels of the Taiyang meridian into the main meridian, and only then enters inwardly to other meridians. When pathogens lodge in the skin and hair, the Xuanfu (pores) become closed. The Qi of the internal organs constantly communicates with external Qi; when open, harmony prevails. When the Xuanfu is closed, internal Qi cannot vent, leading to the generation of heat; this is not because wind-cold transforms into heat. At this stage, one should only disperse the pathogen from the skin and hair; once the Xuanfu opens, the pathogen dissipates with sweat. Mahuang Tang and Guizhi Tang are formulas for dispersing pathogens from the skin and hair, not for clearing internal heat. If the exterior condition remains unresolved, heat accumulates and intensifies daily, reversing from the primary meridian inwardly or transmitting to the Jing-Ru-Shu-He (Well, Spring, Stream, River, Sea) acupoints where meridians intersect. Consequently, heat transmits to other meridians, and symptoms of various meridians appear simultaneously. (Points where meridians emerge are Jing points, where Qi flows like springs are Ru points, where Qi gathers are Shu points, and where Qi enters are He points; this applies to all twelve meridians.)
Once the Taiyang syndrome resolves, if there is no headache or aversion to cold, and the pulse is no longer floating, it indicates that the exterior syndrome has ceased and the pathogen is now intermediate or interior, situated between the Yangming and Shaoyang meridians. The pulse is neither floating nor deep but lies between the muscles, beneath the skin. There are two possibilities here: If the pulse is slightly洪 (surging) and long, it is a Yangming pulse; external symptoms include dry nose and insomnia, treated with Gegen Jieji (Pueraria Muscle-Releasing) method. If the pulse is wiry and rapid, it is a Shaoyang pulse; external symptoms include hypochondriac pain, deafness, bitter taste in the mouth, and alternating chills and fever, treated with Xiaochaihu Tang (Minor Bupleurum Decoction) to harmonize. Generally, Yangming and Shaoyang do not follow the standard root/branch treatment but are treated according to their "middle Qi." If there is even a slight aversion to cold, the pathogen remains in the exterior; even if it has entered the interior, dispersing the pathogen should still be combined.
[Commentary] Muscles themselves cannot transmit pathogens; muscles contain meridians. Meridians are considered "intermediate," the interior refers to organs, and the exterior refers to skin and hair. The Qi and blood of organs rely on meridians for transmission; similarly, heat caused by external pathogens also transmits via meridians. Therefore, Yangming and Shaoyang diseases are both treated via the intermediate. "Intermediate" refers to meridian disease, not disease of the Stomach or Gallbladder (Yangming belongs to the Stomach, Shaoyang to the Gallbladder; these are diseases of the external meridians, not the internal organs). Meridian diseases are treated with harmonizing methods, which must involve sweating to disperse, but this is no longer a method of opening the skin pores. Initially, when pathogens lodge in the exterior, Yin fluids in the meridians are damaged; simply opening the pores allows natural sweating. However, when heat transmits to the intermediate meridians, blood is scorched; although pores may be opened, sweat is blocked by heat and cannot reach the surface. Unskilled physicians, unaware of this, still use pungent-warm herbs to induce sweating, further aiding heat and consuming Yin, leading to dried-up sweat sources and often death due to inability to sweat. Zhang Zhongjing’s harmonizing method merely clears heat pathogens, preserving fluids; once Yin fluids are replenished, sweat naturally surges to the surface, and external pathogens dissipate. This method of nourishing sweat to open the Xuanfu is fundamentally different from forcibly opening the Xuanfu to induce sweat.
If the pathogen is in the Yangming meridian, use muscle-releasing methods; if in the Shaoyang meridian, use harmonizing methods. However, if the disease persists and has transmitted to interior excess-heat, with a pulse that is deep rather than floating, palpable at the level of sinews and bones, this is referred to as Yangming Stomach-Fu disease, distinct from meridian disease (Yangming meridian disease has resolved, and here it has transmitted to the Stomach-Fu in the chest). If the pulse is deep, full, and forceful, and external symptoms include aversion to heat rather than cold, delirium, extreme thirst, and constipation for six to seven days, these are caused by dryness and excess in the intestines and stomach. Mild cases are treated with Daxiehu Tang (Major Bupleurum Decoction), severe cases with the Three Chengqi Decoctions (San Chengqi); heat subsides once stool passes.
[Commentary] When heat pathogens enter the interior, expulsion is difficult; thus, we facilitate bowel movement to drain them, taking the nearest route. Sweating resolves meridian pathogens; it is not that sweat is harmful and needs driving out. Bowel movements expel Fu-pathogens; it is not that feces are difficult and need attacking. Physicians who fail to observe this merely know purgative methods, strictly forbid food and drink, and consider achieving a single bowel movement as their goal, which is laughable!
When cold pathogens directly invade the Three Yin meridians, it is called "Direct Invasion" (Zhi Zhong). This occurs because the governing Qi of the Three Yang meridians is weak, lacking heat to resist the cold. Thus, from the onset, there are cold limbs, tremors, curling up, no thirst, abdominal pain, vomiting, diarrhea, spitting saliva, a face pale as if scraped by a knife, no fever, and a deep, slow, and deficient pulse. This deviates from the usual pattern of transmission from Yang meridians; treatment depends on external symptoms. Mild cases are treated with Lizhong Tang (Regulate the Middle Decoction); severe cases with Jiangfu Tang (Ginger and Aconite Decoction) or Sini Tang (Frigid Extremities Decoction).
[Commentary] Shanghan involves pathogens entering organs via skin, hair, and meridians. Initially虽有 aversion to cold and fever, it ultimately becomes a heat syndrome; such individuals typically have inherent fire. Direct invasion of organs involves persistent aversion to cold without fever; such individuals typically lack inherent fire. One approach releases the exterior and attacks the interior; the other warms the middle and dispels cold; the two paths are clearly distinct. Abnormal presentations exist, such as fever, red face, irritability, removing clothes/blankets, desire for cold drinks, and large pulse—is this not a Yang syndrome? Yet patients die after receiving cooling medicines. Why? Because there is latent Yin within. Palpation reveals a pulse that is weak under the fingers regardless of floating/deep or large/small, especially when pressing to the bone level. Severe cases vomit all teas and medicines. This is Yin excess repelling Yang, corresponding to the syndrome for Baitong Tang plus human urine and pig bile. Zhang Zhongjing discusses both transmitted and direct invasion together precisely to highlight that Yin syndromes can resemble Yang, and Yang syndromes can resemble Yin. For example, Taiyang syndrome presents with headache and fever; if the pulse is floating but unexpectedly deep, it resembles Shaoyin, so Mahuang Fuzi Xixin Tang (Ephedra, Aconite, and Asarum Decoction) is used. Shaoyin syndrome presents with a deep pulse and should have no fever; if fever appears, it resembles Taiyang, requiring Gancao Ganjiang Fuzi Tang (Licorice, Ginger, and Aconite Decoction). Yin syndrome presents with cold limbs, but Yang syndrome can also present with cold limbs; hence, Sini Tang differs from Sini San (Frigid Extremities Powder). Yin syndrome presents with diarrhea, but Yang syndrome can also present with incomplete evacuation (leakage); hence, Lizhong Tang differs from Huanglong Tang (Yellow Dragon Decoction).