古人言诸瘟病者，多作温热之温。夫言温而不言瘟，似为二症，第所言与瘟病
相同，则温瘟为一病也明矣。后人加以 字，变温为瘟，是就病之名目而言，岂可
以温瘟为两症乎。其曰春温、夏温、秋温、冬温，总属强立名色，其实皆因四时感
瘟气而成病耳。其曰风温、湿温、温疟、温暑者，即瘟病而兼风、湿、暑、疟也。
其曰瘟毒者，言瘟病之甚者也。曰热病者，就瘟病之发于夏者而言耳。至于晚发之
说，更属不经。夫冬月寒疠之气，感之即病，那容藏于肌肤半年无恙，至来岁春夏而始
发者乎？此必无之理也，而顾可习而不察欤！至于疫字，传以民皆疾解之，以
其为病，延门阖户皆同，如徭役然。去彳而加 ，不过取其与疾字相关耳。是则瘟
疫二字，乃串讲之辞，若曰瘟病之为疠疫，如是也，须知疫病所该甚广。瘟字原对疫字
不过。瘟疫者，不过疫中之一症耳，始终感温热之疠气而发，故以瘟疫别之。此外
尚有寒疫、杂疫之殊，而瘟疫书中，却遗此二条，竟将瘟疫二字平看，故强分瘟病、
疫病，又各立方施冶，及细按之，其方论又谩无差别，殊少情理，断不可从也。
吁！瘟疫二字尚不明其义意。又奚以治瘟疫哉。
传曰∶疫者民皆疾也。又曰∶疫，疠也，中（去声。）人如磨砺伤物也。夫曰民皆疾
而不言何疾，则疾之所该也广矣。盖受天地之疠气，城市、乡井以及山陬海 所
患皆同，如徭役之役，故以疫名耳。其病千变万化，约言之则有三焉。一曰瘟疫。
夫瘟者，热之始，热者，温之终，始终属热症。初得之即发热，自汗而渴，不恶寒。
其表里分传也，在表则现三阳经症，入里则现三阴经症，入腑则有应下之症。其愈
也，总以汗解，而患者多在热时。其与伤寒不同者，初不因感寒而得，疠气自口鼻
入，始终一于为热。热者，温之终，故名之曰瘟疫耳。二曰寒疫。不论春夏秋冬，
天气忽热，众人毛窍方开，倏而暴寒，被冷气所逼即头痛、身热、脊强。感于风者
有汗，感于寒者无汗，此病亦与太阳伤寒伤风相似，但系天作之孽，众人所病皆同，
且间有冬月而发疹者，故亦得以疫称焉。其治法则有发散、解肌之殊，其轻者或喘
嗽气壅，或鼻塞声重，虽不治，亦自愈。又有病发于夏秋之间，其症亦与瘟疫相似，
而不受凉药，未能一汗即解，缠绵多日而始愈者，此皆所谓寒疫也。三曰杂疫。
其症则千奇百怪，其病则寒热皆有，除诸瘟、诸挣、诸痧瘴等暴怪之病外，如疟痢、
泄泻、胀满、呕吐、喘嗽、厥痉、诸痛、诸见血、诸痈肿、淋浊、霍乱等疾，众人
所患皆同者，皆有疠气以行乎其间，故往往有以平素治法治之不应，必洞悉三才之
蕴而深究脉症之微者，细心入理，一一体察，方能奏效，较之瘟疫更难揣摩。盖治
瘟疫尚有一定之法，而治杂疫竟无一定之方也。且其病有寒者，有热者，有上寒而
下热者，有上热而下寒者，有表寒而里热者，有表热而里寒者，种种变态，不可枚
举。世有瘟疫之名，而未解其义，亦知寒疫之说，而未得其情，至于杂疫，往往皆
视为本病，而不知为疫者多矣。故特表而出之。
古人所说的各种瘟病，大多是指具有温热性质的“温”病。如果说的是“温”而不说“瘟”，看似是两种病症，但既然所描述的症状与瘟病相同，那么温病和瘟病就是同一种疾病，这是很明显的。后人加上“疒”旁（注：原文此处可能有缺字或通假，意指加偏旁变为瘟），将“温”改为“瘟”，这是从疾病的名称角度而言的，怎么可以把温病和瘟病当作两种不同的病症呢？所谓的春温、夏温、秋温、冬温，总归是强行设立的名称类别，其实都是因为感受了四季中的瘟气而形成的疾病。所谓的“风温”、“湿温”、“温疟”、“温暑”，就是在瘟病的基础上兼夹了风、湿、暑、疟邪气。所谓的“瘟毒”，是指病情严重的瘟病。所谓的“热病”，是指发生在夏季的瘟病罢了。至于“晚发”的说法，更是荒诞不经。冬天感受寒疠之气，一旦感染就会发病，怎么可能潜伏在肌肤之中半年安然无恙，等到第二年春夏才发作呢？这绝对是讲不通的道理，怎么能熟习这种说法却不加考察呢！
至于“疫”字，传说解释为百姓都遭受同样的疾苦，因为这种病蔓延门户，家家户户症状都一样，就像徭役一样普遍。去掉“亻”旁加上“疒”旁，不过是取它与疾病相关的意思罢了。因此，“瘟疫”二字，是连缀讲解的辞藻，意思是说瘟病作为一种疠疫，情况就是这样。需要知道，“疫”字所包含的范围非常广泛。“瘟”字原本不足以涵盖“疫”字的全部含义。“瘟疫”一词，不过是众多疫病中的一种表现而已，它始终是由感受温热性质的疠气而引发的，所以用“瘟疫”来特别区分它。此外还有寒疫、杂疫等不同种类，而在关于瘟疫的书籍中，却遗漏了这两类，竟然将“瘟疫”二字等同看待，因此强行区分瘟病和疫病，又分别为它们制定方剂进行治疗，但仔细推敲其方论，又没有实质差别，这很不合情理，绝对不可采纳。
唉！如果连“瘟疫”二字的含义都不清楚，又凭什么去治疗瘟疫呢？
古书说：“所谓疫，就是百姓都遭受同样的疾苦。”又说：“疫，就是疠气，‘中’（读去声）人，就像磨刀石损伤物体一样猛烈。”如果说百姓都遭受疾苦却不说明是什么疾苦，那么疾苦所涵盖的范围就很广了。这是因为接受了天地间的疠气，无论是城市、乡村还是山角海边，人们患的病都是一样的，就像徭役役使众人一样，所以称为“疫”。这种病的变化千奇百怪，概括来说主要有三种。第一种叫“瘟疫”。所谓“瘟”，是热的开始；“热”，是温的终结，从头到尾都属于热症。刚得病时就发热，自汗且口渴，不恶寒。它在表里之间传变，在表则显现三阳经的症状，入里则显现三阴经的症状，进入腑则有应当使用下法治疗的指征。它的痊愈，总是通过发汗解除，而患者多在发热时最为严重。它与伤寒不同的地方在于，起初并不是因为感受寒邪而得的，疠气从口鼻侵入，从头到尾都是热证。热，是温的终结，所以称之为“瘟疫”。第二种叫“寒疫”。不论春夏秋冬，天气突然变热，众人的毛孔刚刚张开，忽然遭遇暴寒，被冷气逼迫就出现头痛、身热、脊柱僵硬。感受风邪的有汗，感受寒邪的无汗，这种病也与太阳伤寒、伤风相似，但属于天灾，众人所患病症相同，而且间或有在冬季发疹的情况，所以也得以称为“疫”。其治疗方法有发散和解肌的不同，轻症的或者气喘咳嗽气机壅滞，或者鼻塞声音沉重，即使不治疗，也能自愈。又有在夏秋之间发病的，症状也与瘟疫相似，但不能耐受寒凉药物，不能一发汗就立即解除，缠绵多日才能痊愈的，这些就是所谓的“寒疫”。第三种叫“杂疫”。其症状千奇百怪，其病性寒热都有，除了各种瘟病、各种惊风抽搐、各种痧瘴等突发怪异疾病之外，如疟疾痢疾、泄泻、胀满、呕吐、喘嗽、厥逆痉挛、各种疼痛、各种出血、各种痈肿、淋证浊尿、霍乱等疾病，众人所患相同的，其中都有疠气在起作用，所以往往用平时治疗其他疾病的方法无效，必须透彻了解天地人的蕴奥，并深入探究脉象和症状细微之处，细心合乎理法，一一详细体察，才能奏效，比瘟疫更难揣摩。大概治疗瘟疫还有一定的法则，而治疗杂疫竟没有固定的方子。而且这种病有的属寒，有的属热，有的上寒下热，有的上热下寒，有的表寒里热，有的表热里寒，种种变态，无法一一列举。世上的人有“瘟疫”之名，却不理解其义，也知道“寒疫”的说法，却不掌握其实情，至于“杂疫”，往往都被视为普通本病，而不知道它是疫病的人很多了。所以特意列出并阐明它。
The various "wen" diseases mentioned by the ancients mostly refer to those with a warm-heat nature, i.e., "Wen" (Warm Disease). Although speaking of "Wen" and not "Wen" (Plague/Wen) seems to imply two different syndromes, since the described symptoms are identical to those of Wenbing, it is evident that Wenbing and Wenyi are the same disease. Later generations added the radical for disease (疒) to change "Wen" to "Wenyi", which is merely a matter of nomenclature; how can one treat them as two distinct syndromes? Terms such as Spring-Wen, Summer-Wen, Autumn-Wen, and Winter-Wen are essentially arbitrary classifications; in reality, they all result from contracting the epidemic qi of the four seasons. Terms like Fengwen (Wind-Warmth), Shiwen (Damp-Warmth), Wen-Nue (Warm-Malaria), and Wen-Shu (Warm-Summerheat) refer to Wenyi complicated by Wind, Dampness, Summerheat, or Malaria pathogens. "Wendu" refers to severe cases of Wenyi. "Rebing" (Heat Disease) specifically refers to Wenyi occurring in summer. As for the theory of "late onset," it is absurd. If one contracts cold epidemic qi in winter, illness should ensue immediately; how could it lie dormant in the skin and muscles for half a year without harm, only manifesting in the following spring or summer? This is logically impossible, yet how can one remain familiar with such ideas without scrutiny!
Regarding the character "Yi" (Epidemic), it is traditionally explained as affecting the people uniformly. Because the disease spreads through households, with everyone exhibiting similar symptoms, much like corvée labor, it is named "Yi". Removing the person radical (亻) and adding the disease radical (疒) simply emphasizes its relation to illness. Thus, "Wenyi" is a compound term meaning that Wenyi manifests as an epidemic. It must be understood that "Yi" covers a broad scope. The character "Wen" originally did not fully encompass "Yi". "Wenyi" is but one manifestation among many epidemics; it always arises from contracting warm-heat epidemic qi, hence it is distinguished by this name. Besides, there are distinctions between Cold-Yi and Mixed-Yi, yet books on Wenyi often omit these two categories. By treating "Wenyi" as a single undifferentiated concept, they artificially separate Wenbing and Yibing, prescribing different formulas for each. However, upon close examination, their formula theories show no substantial difference, lacking logical consistency, and thus should not be followed.
Alas! If the meaning of "Wenyi" is not clear, how can one possibly treat it?
Ancient texts state: "Yi means the people all suffer the same疾 (illness)." It also says: "Yi is Li (pestilential qi); 'Zhong' (to strike/infect, pronounced with falling tone) affects people as sharply as a whetstone damages objects." When it says the people suffer the same illness without specifying what illness, the scope of "illness" is vast. This is because everyone, whether in cities, villages, mountain corners, or seaside areas, accepts the same Tian-Di Li Qi (Heaven-Earth Pestilential Qi). Since it afflicts the masses uniformly, like corvée service, it is called "Yi". The manifestations of this disease are myriad, but broadly categorized into three types.
First is "Wenyi". "Wen" is the beginning of heat; "Re" (Heat) is the end of warmth. From start to finish, it belongs to Heat Syndromes. Upon initial contraction, there is fever, spontaneous sweating, thirst, and aversion-to-cold is absent. Regarding its transmission between exterior and interior: if in the exterior, it presents symptoms of the Three Yang Meridians; if entering the interior, it presents symptoms of the Three Yin Meridians; if entering the Fu organs, it presents indications for purgation. Recovery generally occurs through sweating, and patients are most critical during the febrile stage. Unlike Shanghan (Cold Damage), Wenyi does not originate from cold pathogen invasion; rather, Li Qi enters via the mouth and nose, remaining purely hot throughout. Since "Re" is the culmination of "Wen", it is named "Wenyi".
Second is "Lengyi" (Cold Epidemic). Regardless of the season, if the weather suddenly warms up, causing pores to open, and then sudden cold strikes, forcing cold qi upon the body, symptoms include headache, body heat, and neck stiffness. If affected by Wind, there is sweating; if affected by Cold, there is no sweating. This resembles Taiyang Shanghan (Cold Damage) or Shangfeng (Wind Strike), but it is a natural disaster where everyone suffers similarly. Occasionally, rashes may appear in winter, justifying the term "Yi". Treatment methods vary between dispersing (Fasan) and releasing the muscle layer (Jieji). Mild cases, such as wheezing, cough, chest oppression, nasal congestion, or heavy voice, may resolve spontaneously even without treatment. Another form occurs in mid-summer or autumn, resembling Wenyi but unresponsive to cold-natured herbs, failing to resolve with a single sweat, and lingering for days. These are also termed "Lengyi".
Third is "Zayi" (Mixed Epidemic). Symptoms are bizarre and varied; the pathology involves both Cold and Heat. Excluding acute strange diseases like various Wens, convulsions, and Sha-Zhang, conditions such as Nue-Li (Malaria and Dysentery), Xie-Xie (Diarrhea), Zhang-Man (Distension and Fullness), Ou-Tu (Vomiting), Chuan-Sou (Wheezing and Cough), Jue-Jing (Syncope and Spasm), various pains, various bleeding disorders, various abscesses/swellings, Lin-Zhuo (Strangury and Turbid Urine), and Huoluan (Cholera-like disorder), when suffered uniformly by the masses, indicate the presence of Li Qi. Consequently, standard treatments for other diseases often fail. One must thoroughly understand the principles of Heaven, Earth, and Humanity, deeply investigate the subtleties of pulse and symptoms, and carefully apply rational analysis to achieve efficacy. This is harder to grasp than Wenyi. While Wenyi has fixed treatment principles, Zayi has no fixed formulas. Pathologies may be Cold, Heat, Upper-Cold/Lower-Heat, Upper-Heat/Lower-Cold, Exterior-Cold/Interior-Heat, or Exterior-Heat/Interior-Cold, with countless variations. Many know the name "Wenyi" but not its meaning; some know of "Lengyi" but not its true nature. Regarding "Zayi", it is often mistaken for ordinary endemic diseases, leading to frequent misdiagnosis. Therefore, it is specifically highlighted and elucidated here.