风寒气从外收敛入内，病无臭气触人，间有作臭气者，必待数日转阳明腑证之时，亦只作腐气，不作尸气。
瘟疫气从中蒸达于外，病即有臭气触人，轻则盈于床帐；重则蒸然一室，且专作尸气，不作腐气。以人身
脏腑、气血、津液得生气则香，得败气则臭。瘟疫，败气也，人受之，自脏腑蒸出于肌表，气血、津液逢蒸而
败，因败而溢，溢出有盛衰，充塞有远近也。五行原各有臭气∶木臊、金腥、心焦、脾香、肾腐。以臭得其
正，皆可指而名之。若瘟疫，乃天地之杂气，非臊、非腥、非焦、非腐，其触人不可名状，非鼻观精者，不
能辨之。试察厕间粪气与凶地尸气，自判然矣。
辨之既明，治之毋惑。知为瘟疫而非伤寒，则凡于头痛、发热诸表证，不得误用辛温发散；于
诸里证，当清、当下者，亦不得迟回瞻顾矣。
风寒主收敛，敛则急，面色多绷急而光洁；瘟疫主蒸散，散则缓，面色多松缓而垢晦。人受蒸气则津
液上溢于面，头目之间多垢滞，或如油腻，或如烟熏，望之可憎者，
皆瘟疫之色也。一见此色，虽头痛、发热，不宜轻用辛热
发散；一见舌黄、烦、渴诸里证，即宜攻下，不可拘于下不厌迟之说。
风寒在表，舌多无苔，即有白苔，亦薄而滑；渐传入里，方由白而黄，由黄而燥，由燥而黑。
瘟疫一见头痛、发热，舌上即有白苔，且浓而不滑；或色兼淡黄；或粗如积粉。若传经入胃，则兼二、三色，
又有白苔即燥与至黑不燥者。大抵疫邪入胃，舌苔颇类风寒，以兼湿之故而不作燥耳。惟在表时，舌苔白浓，
异于伤寒。能辨于在表时，不用辛温发散，入里时，而用清凉攻下，斯得矣。
风寒之邪从体表向内收敛侵入，疾病通常没有令人厌恶的气味触及他人，偶尔出现臭气的情况，也一定要等到数日后转化为阳明腑实证时，才只散发腐臭味，而不散发尸臭味。
瘟疫之气由体内蒸腾达于体表，患病即刻就有臭气触及他人，轻则充满床帐周围；重则使整个房间充满热气熏人，且专门散发尸臭味，不散发腐臭味。因为人的脏腑、气血、津液得到生机之气则芳香，得到败坏之气则发臭。瘟疫属于败坏之气，人感染后，它自然从脏腑蒸腾出于肌表，导致气血、津液被蒸腾而败坏，因败坏而溢出，溢出的多少有盛衰之分，充塞的范围有远近之别。五行原本各自对应不同的气味：木对应臊味，金对应腥味，心（火）对应焦味，脾对应香味，肾对应腐味。如果气味符合其正性，都可以指认并命名。至于瘟疫，乃是天地的杂气，不是臊味，不是腥味，不是焦味，也不是腐味，它触动人时的气味无法用语言形容，如果不是鼻子敏锐的人，是不能辨别出来的。试着观察厕所的粪气和凶地死尸的气味，自然就能分辨清楚了。
既然已经辨别清楚，治疗时就不会迷惑。知道是瘟疫而不是伤寒，那么对于头痛、发热等所有表证，就不误用辛温发散的方法；对于各种里证，应当清热或攻下的，也不应迟疑观望了。
风寒主收敛，收敛则导致筋脉拘急，面色多显得紧绷光洁；瘟疫主蒸散，蒸散则导致松弛缓慢，面色多显得松缓且污垢晦暗。人受到蒸气的影响，津液就会上溢于面部，头目之间多有污垢停滞，或者像油腻一样，或者像烟熏一样，看起来让人讨厌的，都是瘟疫的面色。一见到这种面色，即使有头痛、发热症状，也不宜轻易使用辛热发散法；一见到舌苔黄、烦躁、口渴等各种里证，就应当立即攻下，不可拘泥于“攻下不厌迟”的说法。
风寒在表时，舌头上大多没有苔，即使有白苔，也是薄而滑润的；逐渐传入里部，才由白变黄，由黄变燥，由燥变黑。瘟疫一见头痛、发热，舌上立即就有白苔，而且浓厚且不滑润；或者颜色兼带淡黄；或者粗糙得像堆积的粉状物。如果传经入胃，则兼有二、三种颜色，又有白苔即干燥和直到黑色也不干燥的情况。大抵疫邪进入胃部，舌苔颇类似风寒，只是因为兼夹湿邪所以不表现为干燥罢了。只有在表证阶段，舌苔白而浓厚，与伤寒不同。能在表证阶段辨别出来，不使用辛温发散法，进入里证阶段时，使用清凉攻下法，这样就对了。
Wind-cold pathogenic qi converges inward from the exterior, and the disease typically emits no offensive odor to people; if an odor is present, it usually appears only after several days when transforming into Yangming Fu-organ syndrome (a syndrome characterized by heat accumulation in the stomach and intestines), manifesting merely as a putrid smell rather than a corpse-like smell.
Plague pathogenic qi steams outward from the interior; upon infection, an offensive odor immediately permeates the surroundings. Mildly, it fills the bed curtains; severely, it steams through the entire room. It specifically emits a corpse-like smell, not a putrid one. This is because the organs, Qi and blood, and body fluids of the human body become fragrant when receiving vital Qi, but become foul when receiving decaying Qi. Plague is a type of decaying Qi; once contracted by humans, it steams out from the internal organs to the muscle surface. The Qi and blood, and body fluids are steamed and decayed, leading to overflow. The degree of overflow varies in intensity, and the range of obstruction varies in distance. The Five Elements originally correspond to specific odors: Wood corresponds to fishy/foul smell (Sao), Metal to raw/fishy smell (Xing), Heart (Fire) to scorched smell (Jiao), Spleen to sweet/fragrant smell (Xiang), and Kidney to putrid smell (Fu). If the odor aligns with its proper elemental nature, it can be identified and named. However, plague is a miscellaneous Qi of Heaven and Earth; it is neither Sao, nor Xing, nor Jiao, nor Fu. Its odor upon contact is indescribable and cannot be distinguished unless one has a keen sense of smell. One can distinguish it by comparing the odor of a latrine with that of a corpse in a cursed place.
Once clearly distinguished, treatment will not be confused. Knowing it is plague and not Wind-cold means that for all exterior syndromes such as headache and fever, acrid-warm dispersing methods must not be mistakenly used; for various interior syndromes requiring clearing or purging, hesitation should be avoided.
Wind-cold governs convergence; convergence leads to tension, so the facial complexion often appears tight, smooth, and bright. Plague governs steaming and dispersion; dispersion leads to laxity, so the facial complexion often appears loose, slow, dirty, and dull. When affected by steaming Qi, body fluids overflow upward to the face, causing dirtiness and stagnation around the head and eyes, resembling grease or smoke stains, which look repulsive. These are all complexions of plague. Upon seeing this complexion, even if accompanied by headache and fever, acrid-hot dispersing methods should not be lightly employed. Upon seeing interior syndromes such as yellow tongue coating, irritability, and thirst, purgative methods should be applied immediately, without adhering to the saying that "purgation is never too late."
When Wind-cold is at the exterior, the tongue usually lacks a coating; if a white coating exists, it is thin and slippery. As it gradually transmits inward, it changes from white to yellow, from yellow to dry, and from dry to black. In plague, upon the appearance of headache and fever, a white coating appears on the tongue immediately, which is thick and not slippery; it may also have a pale yellow hue or appear coarse like accumulated powder. If the pathogen transmits to the Stomach, the coating may exhibit two or three colors, or remain white yet dry, or turn black yet remain non-dry. Generally, when epidemic pathogens enter the Stomach, the tongue coating resembles that of Wind-cold, but due to the presence of Dampness, it does not become dry. The key distinction during the exterior stage is that the tongue coating is white and thick, differing from Wind-cold. Correct identification during the exterior stage allows for avoiding acrid-warm dispersing methods, and applying cooling and purging methods during the interior stage, which constitutes the correct approach.