伤寒有传经直中。传经者，由太阳传阳明，由阳明传少阳，由少阳传太阴，由太阴传少
阴，
由少阴传厥阴，此循经传也。有太阳不传阳明而经传少阳者，有阳明不传少阳而径入本府者
，
有少阳不传太阴，而径归胃府者，谓之越经传。有传一二经而止者，有始终只在一经者，在
表为寒，在里则为热矣。直中者，不由三阳传入，而径中三阴，有寒无热者也。若兼目疾，
惟三阳有之，太阳宜汗，阳明宜清，少阳宜和，无异法也。羌活主太阳，葛根主阳明，柴胡
主少阳，为报使之药，人所共知，而温经散寒之法，间亦参用。至于分症立法，无关于本科
者，不必赘述也。
温疫之邪，伏于膜原，蒸变不测，吴又可制为达原饮以治之。立论超出千古，举世皆宗
之。
然其症发热头疼，便闭神昏，与外感风寒相似，不可不细辨也。夫风寒从外入内，病无臭气
触人，间有作臭气者，必待传阳明胃府始见。若瘟疫从中达外，病即有臭气触人，轻则透于
床帐，重则盈于房帷，此气之易辨也。风寒主收敛，面色多绷急而光洁。瘟疫主蒸散，散则
缓，面色多松缓而垢晦，此色之易辨也。风寒初起，舌多无胎，即有白胎，亦薄而滑。瘟疫
一见头痛发热，舌上即有白胎，且浓而不滑，或粗如积粉，或色兼微黄，此舌之易辨也。瘟
疫之脉，传变后与风寒颇同，初起时与风寒迥别，风寒在表，一二日，脉多浮，或兼紧兼缓
兼洪而皆浮。迨传入里，始不见浮脉。瘟疫从中道而变，一二日，脉多沉，迨自里出表，脉
始不沉，乃不浮不沉而数，或兼弦兼大而皆不浮。此脉之易辨也。且其见症，必初起忽觉凛
凛，以后但热而不恶寒，以其从内蒸发，非必有感触之因也。设有胁痛耳聋，则邪溢少阳，
腰背项痛，则邪溢太阳，眉棱骨痛，眼眶痛，鼻干不眠，则邪溢阳明，当以柴胡羌活葛根等
，
分经加用。若舌根先黄，渐至中央，邪渐入胃，此三消饮症。若脉长洪而数，大汗多渴，此
邪适离膜原，欲表未表，此白虎汤症。若舌上纯黄色，或变黑色，或生芒刺，或鼻如烟煤，
或大便不行，或大便虽无结粪，而脉象沉实，此皆承气汤症。倘耽延失下，以致循衣摸床，
撮空理线，攻不可，补不可，惟有用陶氏黄龙汤，间有得生者。至于养营清燥，总宜在驱邪
之后也。若邪火上攻于目，赤肿疼痛，畏热羞明，宜专逐疫邪，则目自愈。亦有昼夜壮热，
目中如火燃，如针刺，怕见日光灯光，必须四面遮围，始稍宁静，亦宜注意逐邪，使胃中无
热邪留郁，自然清光大来。又有疫邪传里，遗热下焦，小便不利，邪无输泄，经气郁滞，目
黄如金者，即以茵陈汤治之。或邪火久焰，肾水枯涸，瞳神昏渺，眵泪失光，逐邪之中，
兼用滋阴，不得徒以甘菊蒺藜疗之。总之瘟疫乃时气传染，治宜清火散邪，东垣普济消毒饮
，本为瘟疫而设，以治瘟疫之目疾，其奏效不更速乎？
伤寒病有传经和直中两种情况。所谓传经，是指病邪由太阳经传入阳明经，由阳明经传入少阳经，由少阳经传入太阴经，由太阴经传入少阴经，由少阴经传入厥阴经，这是按照经络顺序相传，称为循经传。有的太阳经病不传给阳明经而直接传给少阳经；有的阳明经病不传给少阳经而直接进入本腑（胃）；有的少阳经病不传给太阴经而直接进入胃腑，这叫做越经传。有的病只传一二经就停止，有的病从头到尾只在一经停留，在表表现为寒证，在里则转化为热证。所谓直中，是指病邪不经过三阳经传入，而是直接侵犯三阴经，只有寒证而没有热证。如果兼有眼疾，只有三阳经的病会出现这种情况：太阳经病适宜用发汗法，阳明经病适宜用清热法，少阳经病适宜用和解法，治疗方法没有不同。羌活主治太阳经病，葛根主治阳明经病，柴胡主治少阳经病，它们作为引导药进入各经，是众人皆知的常识，而温经散寒的方法，偶尔也会参用。至于分症立法的内容，与本学科无关的，不必赘述。
瘟疫的病邪，潜伏在膜原（半表半里的部位），变化莫测，吴又可制定了达原饮来治疗它。其理论论述超越千古，举世都尊崇它。然而它的症状发热头痛、大便闭塞神志昏沉，与外感风寒相似，不能不仔细辨别。风寒之邪从外部侵入内部，疾病没有臭气冲人，偶尔有产生臭气的，必须等到传入阳明胃腑才会出现。若瘟疫之邪从内部通达外部，疾病立即就有臭气冲人，轻则透到床帐，重则充满房间帷幔，这是气味容易辨别之处。风寒主收敛，面色多紧绷急迫且光洁。瘟疫主蒸腾发散，发散则舒缓，面色多松弛缓慢且污垢晦暗，这是色泽容易辨别之处。风寒初起时，舌头上多没有苔，即使有白苔，也是薄而滑润。瘟疫一见头痛发热，舌上立即出现白苔，而且厚腻不滑，或者粗糙像堆积的粉，或者颜色兼带微黄，这是舌象容易辨别之处。瘟疫的脉象，传变之后与风寒颇为相同，初起时与风寒截然不同，风寒在表，一两天内，脉象多浮，或者兼紧、兼缓、兼洪但都表现为浮脉。等到传入里部，才不见浮脉。瘟疫从中道（膜原）发生变化，一两天内，脉象多沉，等到从里出表，脉象才不沉，呈现不浮不沉而数，或者兼弦、兼大但都不浮，这是脉象容易辨别之处。并且其表现的症状，一定是初起突然觉得寒冷战栗，以后只是发热而不恶寒，因为它是从体内蒸发出来的，不一定必须有感触外邪的原因。如果伴有胁痛耳聋，则是邪气溢入少阳经；腰背项痛，则是邪气溢入太阳经；眉棱骨痛、眼眶痛、鼻干失眠，则是邪气溢入阳明经，应当使用柴胡、羌活、葛根等药物，按经络分别加用。如果舌根先变黄，逐渐蔓延至中央，说明邪气逐渐进入胃腑，这是三消饮证。如果脉象长洪而数，大汗出且口渴严重，这是邪气刚刚离开膜原，想要外解但尚未完全外解，这是白虎汤证。如果舌上纯黄色，或者变成黑色，或者生出芒刺，或者鼻子像烟煤一样黑，或者大便不通，或者大便虽然无燥结粪块，但脉象沉实，这都是承气汤证。倘若拖延延误导致攻下失机，以致出现循衣摸床、撮空理线等危重症状，此时攻不可，补不可，只有使用陶华（陶氏）的黄龙汤，偶尔有能救活的。至于滋养营血、清除燥热，总应当在驱除邪气之后进行。如果邪火上攻于目，出现红肿胀痛、畏热羞明，应当专门驱逐疫邪，眼睛自然痊愈。也有昼夜壮热，眼中如火燃烧、如针刺般疼痛，害怕见到日光灯光，必须四面遮挡围护，才能稍微安静，也应当注意驱逐邪气，使胃中没有热邪留滞郁结，自然清朗光明重现。又有疫邪传入里部，余热遗留在下焦，小便不利，邪气没有排泄途径，经气郁滞，导致眼睛黄如金色（黄疸），就用茵陈汤治疗。或者邪火久燃，肾水枯竭，瞳神昏暗模糊，眼屎泪水导致视力丧失，在驱逐邪气的同时，兼用滋阴之法，不得仅仅用甘菊、蒺藜来治疗。总之瘟疫是时气传染所致，治疗适宜清火散邪，李东垣的普济消毒饮，原本就是为瘟疫而设，用它来治疗瘟疫引起的眼疾，难道不是见效更快吗？
Typhoid fever (Shanghan) involves transmission along meridians (Chuanjing) and direct invasion (Zhizhong). Transmission along meridians refers to the pathogen moving from the Taiyang meridian to the Yangming meridian, from Yangming to Shaoyang, from Shaoyang to Taiyin, from Taiyin to Shaoyin, and from Shaoyin to Jueyin; this sequential progression is called "transmission along the meridians" (Xunjingzhuan). In some cases, Taiyang disease does not transmit to Yangming but directly transmits to Shaoyang; in others, Yangming disease does not transmit to Shaoyang but enters its corresponding fu-organ (Stomach) directly; similarly, Shaoyang disease may not transmit to Taiyin but enters the Stomach directly. This is termed "transmission skipping a meridian" (Yuejingzhuan). Some diseases stop after transmitting through one or two meridians, while others remain confined to a single meridian throughout. Exterior manifestations present as cold syndromes, whereas interior manifestations transform into heat syndromes. Direct invasion (Zhizhong) occurs when the pathogen bypasses the three yang meridians and directly attacks the three yin meridians, presenting with cold symptoms without heat. When accompanied by eye diseases, only conditions involving the three yang meridians are relevant: Taiyang disorders require diaphoresis (Hanfa), Yangming disorders require clearing heat (Qingfa), and Shaoyang disorders require harmonization (Hefa); the therapeutic principles remain consistent. Qianghuo (Notopterygii Rhizoma et Radix) governs Taiyang, Gegen (Puerariae Lobatae Radix) governs Yangming, and Chaihu (Bupleuri Radix) governs Shaoyang; these herbs act as guiding agents (Baoshizhiyao) to specific meridians, a fact well known to practitioners. Methods for warming meridians and dispelling cold are occasionally employed. Details regarding syndrome differentiation and prescription formulation unrelated to ophthalmology need not be elaborated here.
The pathogenic factor of warm plague (Wenyi) lies latent in the membranous origin (Moyuan), undergoing unpredictable transformations. Wu Youke formulated Daren Yin (Reach the Origin Decoction) to treat it. His theoretical discourse transcends antiquity and is revered universally. However, its symptoms—fever, headache, constipation, and mental confusion—are similar to external contraction of wind-cold, necessitating careful differentiation. Wind-cold enters from the exterior inward; the disease typically lacks offensive odor. If an odor is present, it usually appears only after transmission to the Yangming Stomach fu-organ. In contrast, warm plague spreads from the interior outward; the disease immediately emits an offensive odor, which may permeate bed curtains in mild cases or fill the room in severe cases. This difference in odor is easily distinguishable. Wind-cold tends to contract, resulting in a tight, smooth, and lustrous complexion. Warm plague tends to steam and disperse, leading to a loose, relaxed, dull, and dirty complexion. This difference in facial appearance is easily distinguishable. At the onset of wind-cold, the tongue usually has no coating; if a white coating exists, it is thin and slippery. Upon the first appearance of headache and fever in warm plague, a white coating appears on the tongue, thick and non-slippery, resembling piled powder, or slightly yellowish. This difference in tongue presentation is easily distinguishable. The pulse in warm plague becomes similar to that of wind-cold after transmission, but differs significantly at the onset. With wind-cold in the exterior, within one or two days, the pulse is mostly floating, possibly combined with tight, slow, or surging qualities, yet always floating. Once transmitted inward, the floating quality disappears. Warm plague transforms from the middle pathway (membranous origin); within one or two days, the pulse is mostly deep. As it moves from interior to exterior, the pulse ceases to be deep, becoming neither floating nor deep but rapid, possibly combined with wiry or large qualities, yet remaining non-floating. This difference in pulse diagnosis is easily distinguishable. Furthermore, the clinical presentation typically begins with sudden chills, followed by persistent fever without aversion to cold, as the heat emanates from within rather than being caused by external contact. If hypochondriac pain and deafness occur, the pathogen has overflowed into the Shaoyang meridian; if lower back, neck, and occipital pain occur, it has overflowed into the Taiyang meridian; if supraorbital pain, orbital pain, dry nose, and insomnia occur, it has overflowed into the Yangming meridian. In such cases, Chaihu, Qianghuo, and Gegen should be added according to the affected meridian. If the root of the tongue turns yellow first, spreading gradually to the center, indicating the pathogen is entering the Stomach, this is Sanxiao Yin (Three Eliminations Decoction) syndrome. If the pulse is long, surging, and rapid, accompanied by profuse sweating and intense thirst, the pathogen has just left the membranous origin and is attempting to exit via the exterior but has not fully done so; this is Baihu Tang (White Tiger Decoction) syndrome. If the tongue is purely yellow or turns black, develops prickles, the nose appears like soot, defecation is obstructed, or although there is no hard stool, the pulse is deep and solid, these are Chengqi Tang (Order the Qi Decoction) syndromes. If treatment is delayed, failing to use purgatives appropriately, leading to critical signs such as grasping at clothes or empty air, where both attacking and tonifying are contraindicated, Tao’s Huanglong Tang (Yellow Dragon Decoction) must be used; survival is possible in rare cases. Nourishing the nutritive level and clearing dryness should generally be performed only after expelling the pathogen. If pathogenic fire attacks the eyes, causing redness, swelling, pain, photophobia, and heat intolerance, one should focus solely on eliminating the epidemic pathogen, and the eyes will heal naturally. In cases of day-and-night high fever, sensation of burning or needle-like pain in the eyes, and extreme sensitivity to sunlight or artificial light, requiring complete enclosure for comfort, attention must also be paid to expelling the pathogen to prevent heat stagnation in the Stomach, allowing clear vision to return. If the epidemic pathogen transmits inward, leaving residual heat in the lower jiao, causing difficult urination and stagnant qi due to lack of excretion, resulting in golden-yellow jaundice of the eyes, Yincheng Tang (Artemisiae Scopariae Decoction) should be administered. If pathogenic fire burns for a long time, depleting kidney water, leading to blurred pupils and loss of vision due to discharge, nourishing yin should be combined with pathogen expulsion; relying solely on Ganju (Chrysanthemi Flos) and Jili (Tribuli Fructus) is insufficient. In summary, warm plague is contagious via seasonal qi; treatment requires clearing fire and dispersing pathogens. Puji Xiaodu Yin (Universal Benefit Detoxification Decoction) by Li Dongyuan was originally designed for warm plague; using it to treat eye diseases caused by warm plague would undoubtedly yield faster results.