杂病用药品过多或无大害，即如健脾者多用白术固已，再加山药可也，再加扁豆亦可也，再
加莲肉、枣肉亦无不可也。即如补肾者多用熟地固已，再加枸杞可也，再加菟丝亦可也，再加苁蓉、
首乌、芡实、杜仲亦无不可也。补药固不厌多，即杂症药品过繁亦为害尚浅，觉其不善，速为减
去或可挽回，而瘟疫不能也。即如葛根治瘟疫药中至和平之品，若邪在太阳，加之太早反足以引邪
入阳明矣。又如葛根与白芷均属阳明散剂，而白芷温散，葛根凉散。白芷散阳明风寒之邪，葛根
散阳明瘟热之邪。若瘟邪之在阳明，用葛根而再用白芷，必然掣肘，恐不似他症用药繁多之帖然
无事矣。所以瘟疫用药，按其脉症，真知其邪在某经，或表或里，并病合病，
单刀直入，批隙导 ，多不过五六味而止。至于分两之重轻则在临时，看其人之老少虚实，病之
浅深进退，而酌用之，所以书内记载之方，大半止有炮制而无分两，欲以变通者，俟诸人耳。
余于疫症，既分三种，曰瘟疫，曰寒疫，曰杂疫，三者具而疫症全矣。然犹未也。忆某年，一
冬无雪，天气温和，至□□春不雨，入夏大旱，春杪即疫疠盛行。正瘟疫殊少，而杂疫颇多，有小
儿发疹者，有大人发疹者，有小儿疹后而患痢患泄泻者，有大人患痢患泄泻者，有先泻而后痢者，
有先痢而后泻者，有泻痢而兼腹胀痛者，有胀痛而不泻痢者，有泻痢既愈，迟之又久而复作者，
有瘟症既愈，迟之又久而复作者，有复作而与前不同者，有腹胀而不痛者，有痛而不胀者，有不思
饮食者，有单发热者，有先瘟症而后不语者，有肿头面者，有周身长疖者，有长疥者，有霍乱者，
有身痒者，有患瘟症而兼泄泻者，城市乡井，缘门阖户皆同。此岂达原饮一方所能疗欤！其治法
亦与平常患泻痢、胀痛等疾亦异。此皆杂疫之类也。要之，杂疫无病不有，惟无咽膈梦遗之为疫
病者耳。
治疗杂病时，用药种类过多通常不会造成大的危害。例如健脾的药物，如果已经大量使用了白术，那么再加入山药是可以的，再加入扁豆也是可以的，甚至再加入莲子肉、枣肉也没有问题。同样，补肾的药物，如果已经大量使用了熟地黄，那么再加入枸杞是可以的，再加入菟丝子是可以的，再加入肉苁蓉、何首乌、芡实、杜仲也没有问题。补益类药物确实不嫌多，即使是杂症用药繁杂，其危害也尚且轻微，如果觉得不妥，迅速减少药味或许还能挽回。但瘟疫病却不行。例如葛根是治疗瘟疫药物中性质最为平和的一味，如果邪气在太阳经（足太阳膀胱经受邪），过早加入葛根反而足以引导邪气传入阳明经（足阳明胃经受邪）。又如葛根与白芷都属于治疗阳明病的发散药，但白芷性温而散，葛根性凉而散。白芷发散的是阳明经的风寒之邪，葛根发散的是阳明经的瘟热之邪。如果瘟邪位于阳明经，使用葛根的同时又使用白芷，必然会产生掣肘（相互牵制阻碍药效），恐怕就不像其他病症用药繁多那样安然无事了。所以治疗瘟疫用药，必须根据脉象和症状，确切知道邪气在哪一经，是在表还是在里，或者是并病（两经或三经同时发病）合病（两经或三经先后发病），要单刀直入，抓住关键，药味多不过五六味就停止。至于剂量的轻重则取决于临时的判断，观察患者的老少虚实，病情的深浅进退，从而斟酌使用。因此书中记载的方剂，大半只有炮制方法而没有剂量，是为了让变通运用的人自行斟酌罢了。
我在疫症方面，将其分为三种：曰瘟疫，曰寒疫，曰杂疫，三者具备，疫症就全面了。然而这还不够。记得某年，整个冬天没有下雪，天气温和，到了春天不下雨，进入夏天大旱，春末即疫病盛行。当时典型的瘟疫很少，而杂疫很多，有小儿出疹子的，有大人出疹子的，有小儿出疹后患痢疾或泄泻的，有大人患痢疾或泄泻的，有先泄泻而后患痢疾的，有先患痢疾而后泄泻的，有泄痢兼腹胀痛的，有胀痛而不泄痢的，有泄痢痊愈后，过了很久又复发的，有瘟症痊愈后，过了很久又复发的，有复发且与前次不同的，有腹胀但不痛的，有痛但不胀的，有不思饮食的，有单纯发热的，有先患瘟症而后不能说话的，有头面部肿的，有周身长疖子的，有长疥疮的，有霍乱的，有身上痒的，有患瘟症兼泄泻的，城市和乡村，家家户户都是同样的症状。这难道是一方达原饮所能治疗的吗！其治法也与平常治疗泄痢、胀痛等疾病不同。这些都属于杂疫的范畴。总之，杂疫没有哪种病不存在，只是没有以咽膈不适、梦遗作为主要表现的疫病罢了。
When treating miscellaneous diseases, using too many types of herbs usually does not cause significant harm. For example, in invigorating the Spleen (Zang-Fu Organ responsible for transformation and transportation), if a large amount of Atractylodis Rhizoma (Baizhu, 白术) has already been used, then adding Dioscoreae Rhizoma (Shanyao, 山药) is acceptable; adding Dolichoris Semen (Bian Dou, 扁豆) is also acceptable; even adding Nelumbinis Semen (Lian Rou, 莲肉) and Zizyphi Fructus (Zao Rou, 枣肉) poses no problem. Similarly, in tonifying the Kidney (Zang-Fu Organ storing essence), if a large amount of Rehmanniae Radix Preparata (Shu Di Huang, 熟地) has already been used, then adding Lycii Fructus (Gou Qi, 枸杞) is acceptable; adding Cuscutae Semen (Tu Si Zi, 菟丝子) is acceptable; adding Cistanches Herba (Rong Rong, 苁蓉), Polygoni Multiflori Radix (Shou Wu, 首乌), Euryales Semen (Qian Shi, 芡实), and Eucommiae Cortex (Du Zhong, 杜仲) is also acceptable. Tonifying herbs are indeed never too many; even if the prescription for miscellaneous diseases is overly complex, the harm remains slight. If one feels it is inappropriate, reducing the number of herbs quickly may still salvage the situation. However, this is not the case with Plague (Yi Bing, 瘟疫). For instance, Puerariae Radix (Ge Gen, 葛根) is one of the mildest herbs in plague treatment. If the pathogenic factor is in the Taiyang Channel (Taiyang Jing, 太阳经 - the Foot-Taiyang Bladder Meridian), adding Ge Gen too early may actually guide the pathogen into the Yangming Channel (Yangming Jing, 阳明经 - the Foot-Yangming Stomach Meridian). Furthermore, both Puerariae Radix (Ge Gen, 葛根) and Angelicae Dahuricae Radix (Bai Zhi, 白芷) belong to dispersing agents for Yangming disorders, but Bai Zhi is warm and dispersing, while Ge Gen is cool and dispersing. Bai Zhi disperses Wind-Cold pathogens in the Yangming channel, whereas Ge Gen disperses Warm-Heat pathogens in the Yangming channel. If the Warm-Heat pathogen is located in the Yangming channel, using Ge Gen together with Bai Zhi will inevitably cause mutual interference (che zhou, 掣肘), and it is likely that the outcome will not be as safe as when multiple herbs are used for other miscellaneous diseases. Therefore, when treating Plague, medication must be based on pulse and symptoms, accurately determining which channel the pathogen resides in, whether it is in the Exterior or Interior, or if it involves concurrent disease (Bing Bing, 并病 - simultaneous involvement of two or more channels) or combined disease (He Bing, 合病 - sequential involvement of two or more channels). One should strike directly at the core issue, addressing the key points, limiting the prescription to no more than five or six herbs. As for the dosage, it depends on temporary judgment, observing the patient's age and deficiency/excess status, and the depth and progression of the disease, to adjust accordingly. Hence, most prescriptions recorded in this book contain only processing methods without specific dosages, intending for practitioners to exercise flexibility and discretion.
Regarding epidemic diseases, I divide them into three categories: Plague (Wen Yi, 瘟疫), Cold Plague (Han Yi, 寒疫), and Miscellaneous Plague (Za Yi, 杂疫). With these three, the spectrum of epidemic diseases is complete. However, this is not sufficient. I recall a certain year where there was no snow throughout the winter, and the weather remained mild. In spring, there was no rain, and by summer, there was severe drought. By the end of spring, epidemics prevailed. At that time, typical Plague cases were few, while Miscellaneous Plague cases were numerous. There were children with exanthems, adults with exanthems, children suffering from dysentery or diarrhea after exanthems, adults suffering from dysentery or diarrhea, those who had diarrhea first followed by dysentery, those who had dysentery first followed by diarrhea, those with diarrhea/dysentery accompanied by abdominal distension and pain, those with distension/pain but no diarrhea/dysentery, those whose diarrhea/dysentery healed but recurred after a long delay, those whose plague recovered but recurred after a long delay, those who recurred with different symptoms from before, those with abdominal distension but no pain, those with pain but no distension, those with loss of appetite, those with fever alone, those who became aphasic after initial plague symptoms, those with swelling of the head and face, those with boils all over the body, those with scabies, those with cholera, those with pruritus, those with plague accompanied by diarrhea. In cities and villages, every household exhibited similar symptoms. Could such a wide variety be treated by a single formula like Da Yuan Yin (Origin-Reaching Decoction)? The treatment methods also differ from those for ordinary diarrhea, dysentery, distension, and pain. These all fall under the category of Miscellaneous Plague. In summary, Miscellaneous Plague encompasses virtually any disease, except for those manifesting primarily with throat/pharynx discomfort or nocturnal emission.