疹出于胃，古人言热毒未入于胃而下之，热乘虚入胃，故发斑；热毒已入于胃，不即下之，热不得泄，
亦发斑。此指误下、失下而言。夫时行疫疹，未经表下，有热不一日而即发者，有迟至四、五日而仍不透
者。其发愈迟，其毒愈重。一病即发，以其胃本不虚，偶染邪气，不能入胃，犹之墙垣高硕，门户紧密，
虽有小人，无从而入，此又可所谓达于募原者也。至于迟至四、五日而仍不透者，非胃虚受毒已深，即发
表攻里过当。胃为十二经之海，上下十二经都朝宗于胃，胃能敷布十二经，荣养百骸，毫发之间，靡所
不贯。毒既入胃，势必亦敷布于十二经，残害百骸。使不有以杀其炎炎之势，则百骸受其煎熬，不危何待？
瘟既曰毒，其为火也明矣。且五行各一其性，惟火有二∶曰君，曰相。内阴外阳，主乎动者也。火之为病，
其害甚大，土遇之而赤，金遇之而熔，木遇之而燃，水不胜火则涸，故《易》曰∶燥万物者，莫 乎
火。古人所谓元气之贼也。以是知火者疹之根，疹者火之苗也。如欲其苗之外透，非滋润其根，何能畅茂？
一经表散，燔灼火焰，如火得风，其焰不愈炽乎？焰愈炽，苗愈遏矣，疹之因表而死者，比比然也。其
有表而不死者，乃麻疹、风疹、暑疹之类。有谓疹可治而斑难医，人或即以疫疹为斑耳。夫疹亦何不可治
之有？但人不敢用此法耳！
疹毒发于胃，古人认为热毒尚未进入胃腑时若使用泻下法，热气便会乘虚侵入胃中，从而导致发斑；若热毒已经入胃，却未及时使用泻下法，热气无法宣泄，同样会引发发斑。这是指误用泻下或未能及时泻下而言的。至于时行疫疹，在未经过解表或泻下治疗的情况下，有的发热不到一天就立即发出疹子，有的则延迟至四、五天仍然透发不出来。疹子发出得越迟，说明毒邪越重。发病即发疹，是因为患者胃气原本不虚，偶然感染邪气，邪气不能深入胃腑，这就好比墙垣高大坚固，门户紧密，虽然有小人（邪气），也无从进入，这就是吴又可所说的邪气到达募原的情况。至于延迟至四、五天仍然透发不出来的，如果不是因为胃气虚弱导致受毒深重，就是之前的解表或攻里治疗过于猛烈不当。胃是十二经脉的海汇，上下十二经都朝宗于胃，胃能敷布气血于十二经，荣养全身骨骼形体，毫发之间，无不贯通。毒邪既然进入胃中，势必也会敷布于十二经，残害全身百骸。如果不采取措施遏制其炽盛之势，那么全身百骸将受到煎熬，不危险还等待什么呢？瘟疫既然称为“毒”，它属于火邪是显而易见的。而且五行各有其特性，只有火有两种：曰君火，曰相火。内阴外阳，主司运动。火邪致病，危害极大，土遇到火会变红，金遇到火会熔化，木遇到火会燃烧，水不胜火则会干涸，所以《易经》说：“使万物干燥的，没有比火更厉害的了。”古人称火为元气的贼寇。由此可知，火是疹的根本，疹是火的苗头。如果想要火的苗头向外透发，不滋润其根本，怎么能茂盛呢？一旦使用解表发散法，如同燔灼的火焰，又像火得了风助，火势不是更加炽烈吗？火势越炽烈，疹苗就越被遏抑，疹子因为解表而致死的，比比皆是。那些解表后没有死亡的，乃是麻疹、风疹、暑疹之类的病证。有人说疹容易治而斑难医，有人便把疫疹当作斑来看待。其实疹又有什么不可治的呢？只是人们不敢使用这种方法罢了！
The rash originates in the Stomach. The ancients stated that if purgation is used before the heat-toxin has entered the Stomach, the heat will enter the Stomach vacuously, thus causing macules (maculae); conversely, if the heat-toxin has already entered the Stomach but purgation is not immediately applied, the heat cannot be discharged, also resulting in macules. This refers to the errors of inappropriate or delayed purgation. Regarding epidemic rashes, without prior treatment with exterior-releasing or purgative methods, some fevers manifest rashes within a day, while others delay for four or five days without fully erupting. The later the eruption, the heavier the toxin. Immediate eruption occurs because the Stomach Qi was originally not deficient; upon accidental infection by pathogenic factors, the pathogens cannot penetrate the Stomach. This is like high walls and tight doors: although petty people (pathogens) exist, they have no entry. This corresponds to Wu Ke-yi’s concept of pathogens reaching the Mu Yuan (Moyuan / Pericardium area). However, cases delaying four to five days without eruption are either due to deficient Stomach Qi allowing deep toxin penetration, or due to excessive exterior-releasing or interior-purging treatments. The Stomach is the Sea of the Twelve Meridians; all twelve meridians converge upon it. The Stomach distributes nutrients to the twelve meridians and nourishes the entire body, penetrating every hair and pore. Once the toxin enters the Stomach, it inevitably spreads through the twelve meridians, damaging the whole body. If its blazing intensity is not suppressed, the body will suffer severe torment, leading inevitably to danger. Since plague is termed "toxin," it is clearly Fire. Among the Five Elements, each has one nature, except Fire, which has two: Ministerial Fire (Jun Huo) and Secretary Fire (Xiang Huo). It is Yin internally and Yang externally, governing movement. Fire diseases cause great harm: Earth turns red when meeting Fire, Metal melts, Wood burns, Water dries up when unable to overcome Fire. Thus, the *I Ching* states: "Nothing dries things more than Fire." The ancients called Fire the thief of Original Qi. Therefore, Fire is the root of the rash, and the rash is the sprout of Fire. To make the sprouts emerge outwardly, one must nourish the root; otherwise, lush growth is impossible. Using exterior-releasing dispersal methods is like fanning flames; as wind increases fire, the blaze intensifies. The fiercer the flame, the more suppressed the sprouts. Deaths from rashes due to improper dispersal are common. Those who survive dispersal typically have Measles (Ma Zhen), Wind Rash (Feng Zhen), or Summerheat Rash (Shu Zhen). Some claim rashes are easy to treat while macules are difficult, confusing epidemic rashes with macules. In fact, rashes are treatable; it is merely that practitioners dare not use this method.