伏温之病，随经可发，经训昭垂，已无疑义。乃张石顽谓温邪之发必由少阳；陆九芝谓温热病必发于阳明；陈平伯
则以肺胃为温邪必犯之地；吴又可又以膜原为温疫伏邪之所。诸家所论，虽亦各有所见，但只举温病之一端，而不可以
概温病之全体。至吴鞠通《条辨》，横分三焦，谓凡病温者，必始于上焦手太阴，是以时感风温之证，指为伏气发温之
病，彼此混而不分，其背谬为尤甚。学人当本古圣经文，悉心参究，确知温病之发，随经可动，临证时，始有真知灼见，
而不至有他歧之惑也。
伤寒之邪，自表传里，里证皆表证所侵入；温热之邪，自里达表，表证皆里证所浮越；惟疫邪由膜络中道，随表里
虚实，乘隙而发，不循经络传次，亦不能一发便尽。吴又可发明九传，及热结旁流，胶闭而非燥结，皆为特识。且伤寒
由气分陷入血分，温热由血分转出气分，故伤寒多始于太阳，温热多始自阳明，或始自少阴。此即热归于气，或归于血
之明辨也。
按《素问·热论》伤寒曰∶人之伤于寒也，则为病热，热虽甚不死。其两感于寒而病者，必不免于死。又曰∶凡病
伤寒而成温病者，先夏至日为病温，后夏至日为病暑。又曰∶藏于精者，春不病温。初无传染之说。张仲景曰∶《阴阳
大论》云∶冬时严寒，万类深藏，君子固密，则不伤于寒，触冒之者，乃名伤寒耳。四时之气皆能为病，以伤寒为毒者，
以其最成杀厉之气也。中而病者，名曰伤寒，不即病者，寒毒藏于肌肤，（孙真人作肌骨之中）至春变为温病，至夏变
为暑病，热极重于温也。是以辛苦之人，春夏多为温热病，皆由冬时触寒所致。又曰∶十一月、十二月，寒冽已严，为
病则重。迥考《素问》、仲景及诸家之论，皆云冬时触冒寒毒所致，非是猝然传染也。
伏气温病，随着经络的传变而发作，这一经典训示已明确无误，不容置疑。然而张石顽认为温邪的发作必然经过少阳经；陆九芝认为温热病必然发于阳明经；陈平伯则认为肺和胃是温邪必定侵犯的部位；吴又可又认为膜原（半表半里的部位）是温疫伏邪潜伏的地方。各家所论述的观点，虽然各有其独到见解，但都只是列举了温病的某一个方面，而不能概括温病的整体全貌。至于吴鞠通在《温病条辨》中，机械地划分三焦（上、中、下焦），认为凡是患温病的人，一定始于上焦手太阴肺经，从而将时行感受风邪引起的风温证，误认为是伏气引发的温病，两者混淆不分，这种错误尤为严重。学习中医的人应当依据古代经典经文，悉心研究探讨，确切地知道温病的发作是随经络而动，在临证诊疗时，才能拥有真知灼见，而不致被其他错误的观点所迷惑。
伤寒的病邪，从体表传入体内，里证都是由表证侵入所致；温热的病邪，从体内达于体表，表证都是由里证向外浮越而出；只有疫疠之邪，是从膜络的中道出发，根据表里虚实的情况，乘虚而入而发作，不遵循经络的传变次序，也不能一次发作就全部结束。吴又可阐发了“九传”理论，以及热结旁流（肠道有燥屎内结，却排出稀水）、胶闭而非燥结等病症，这些都是独到的见识。而且伤寒是由气分陷入血分，温热病是由血分转出气分，所以伤寒多始于太阳经，温热病多始自阳明经，或者始自少阴经。这就是热邪归于气分或归于血分的明确辨析。
按《素问·热论》记载：人受寒邪侵袭，就会得发热病，即使热势很盛也不会死亡。如果两感于寒（同时感受寒邪且病情危重）而发病的，就一定难免于死。又说：凡是患伤寒而转化为温病的人，夏至日之前得的叫温病，夏至之后得的叫暑病。又说：精气藏守固密的人，春天就不会得温病。起初并没有传染的说法。张仲景说：《阴阳大论》指出：冬季严寒，万物深藏，君子注意固护正气，就不受寒邪伤害，触犯冒犯寒气的，才叫做伤寒。四季的气候都能致病，以伤寒为毒害最大的，是因为它形成了最肃杀厉烈的邪气。中邪而立即发病的，名叫伤寒；没有立即发病的，寒毒潜伏在肌肤之间（孙思邈认为是肌骨之中），到了春天变为温病，到了夏天变为暑病，暑热极盛比温病更重。因此，辛勤劳作的人，春夏季节多为温热病，这都是由冬季触犯寒气所致。又说：十一月、十二月，寒冷已经非常严酷，此时生病则病情较重。综合考察《素问》、张仲景及诸家的论述，都说这是冬季触犯寒毒所致，并不是突然之间的互相传染。
The disease of latent warmth (Fuwén) erupts along the meridians; this classical instruction is clear and beyond doubt. However, Zhang Shiwang claimed that the eruption of warm pathogenic factors must proceed through the Shaoyang meridian; Lu Jiuzhi asserted that warm-heat diseases must originate in the Yangming meridian; Chen Pingbo held that the lungs and stomach are the sites inevitably invaded by warm pathogens; Wu Ke-you further posited that the Mo-yuan (a location between the interior and exterior) is where epidemic warm pathogens lie latent. Although each school’s discussion has its own insights, they only mention one aspect of warm diseases and cannot generalize the entirety of warm diseases. As for Wu Jutong’s *Wenbing Tiaobian* (Systematic Differentiation of Warm Diseases), he rigidly divided the Sanjiao (Triple Burner: Upper, Middle, Lower), stating that anyone suffering from a warm disease must begin at the Upper Jiao Hand-Taiyin Lung meridian. Consequently, he misidentified seasonal wind-warmth patterns as diseases caused by latent qi erupting into warmth, confusing the two without distinction; this error is particularly egregious. Students should base their studies on ancient classic texts, carefully investigate, and firmly understand that the eruption of warm diseases moves with the meridians. Only then can they possess true insight during clinical practice and avoid confusion by divergent theories.
The pathogen of Cold Damage (Shanghan) transmits from the exterior to the interior; all interior syndromes are invaded by exterior syndromes. The pathogen of warm-heat reaches from the interior to the exterior; all exterior syndromes float outward from interior syndromes. Only the epidemic pathogen originates from the middle pathway of the membrane network (Mo-luo), taking advantage of gaps based on exterior-interior and deficiency-excess conditions to erupt. It does not follow the sequential transmission of meridians, nor can it be exhausted in a single eruption. Wu Ke-you elucidated the "Nine Transmissions" (Jiu Chuan), as well as heat-binding with purgation of surrounding fluid (Rejie Pangliu) and sticky obstruction rather than dry binding; these were his unique insights. Furthermore, Cold Damage sinks from the Qi level into the Blood level, while warm-heat emerges from the Blood level back to the Qi level. Therefore, Cold Damage often begins at the Taiyang meridian, whereas warm-heat often starts at the Yangming meridian or the Shaoyin meridian. This constitutes a clear differentiation between heat returning to the Qi level or the Blood level.
According to the *Suwen·Relun* (Plain Questions: Treatise on Heat): When humans are injured by cold, they develop febrile diseases; even if the fever is severe, death is unlikely. However, those who suffer from "Lianggan Yu Han" (simultaneous contraction of cold affecting both exterior and interior) will inevitably die. It also states: For those who contract Cold Damage and subsequently develop warm diseases, those occurring before the Summer Solstice are called "Wen" (Warmth), and those after are called "Shu" (Summer Heat). It further states: Those whose essence is preserved and stored securely will not suffer from warmth in spring. Initially, there was no concept of contagion. Zhang Zhongjing stated: The *Yinyang Dalun* says: In winter, when the cold is severe, all things hide deeply. If gentlemen maintain their solidity and integrity, they will not be injured by cold; those who encounter it are said to have contracted Cold Damage. The qi of the four seasons can all cause disease, but Cold Damage is considered the most toxic because it forms the most killing and fierce qi. Those who fall ill immediately upon exposure are named "Cold Damage"; those who do not fall ill immediately harbor the cold toxin within the skin and muscles (Sun Simiao described it as within the muscle and bone). By spring, it transforms into a warm disease; by summer, it transforms into a summer heat disease, which is more severe than warmth. Thus, hardworking people often suffer from warm-heat diseases in spring and summer, all caused by encountering cold in winter. It also states: In the eleventh and twelfth months, the cold is already severe, so illnesses contracted then are heavier. Reviewing the discussions in the *Suwen*, Zhang Zhongjing, and various other schools, all state that these are caused by encountering cold toxins in winter, not by sudden contagion.