一寒方之制。为清火也。为除热也。夫火有阴阳。热分上下。据古方书。咸谓黄连清心。黄芩
清肺。石斛、芍药清脾。龙胆清肝。黄柏清肾。今之用者。多守此法。亦是胶柱法也。大凡寒凉之物。
皆能泻火。岂有凉此而不凉彼者。但当分其轻清重浊。性力微甚。用得其宜。则善矣。夫轻清者宜以清上。
如黄芩、石斛、连翘、天花粉之属也。重浊者宜于清下。如栀子、黄柏、龙胆、滑石之属也。性力
之浓者能清大热。如石膏、黄连、芦荟、苦参、山豆根之属也。性力之缓者能清微热。如地骨皮、玄参、
贝母、石斛、童便之属也。以攻而用者去实郁之热。如大黄、芒硝之属也。以利而用者去癃闭之热。
如木通、茵陈、猪苓、泽泻之属也。以补而用者去阴虚枯燥之热。如生地、二冬、芍药、梨浆、细甘草
之属也。方书之分经用药者。意正在此。但不能明言其意耳。然火之甚者在上。亦宜重浊。火之微者
在下。亦可轻清。夫宜凉之热。皆实热也。实热在下。自宜清利。实热在上。不可升提。盖火本属阳。
宜从阴治。从阴治者宜降。升则反从其阳矣。经曰。高者抑之。义可知也。外如东垣有升阳散火之法。
此以表邪生热者设。不得与伏火内炎者并论。（表邪生热。当作郁热外发为妥。）
The formulation of cold-natured prescriptions aims to clear fire and eliminate heat. Fire is categorized into Yin fire and Yang fire, while heat is differentiated between the Upper Jiao (Upper Burner) and Lower Jiao (Lower Burner). According to ancient medical texts, it is generally believed that Huanglian (Coptidis Rhizoma) clears Heart fire, Huangqin (Scutellariae Radix) clears Lung heat, Shihu (Dendrobii Caulis) and Shaoyao (Paeoniae Radix) clear Spleen heat, Longdan (Gentianae Radix) clears Liver fire, and Huangbai (Phellodendri Cortex) clears Kidney fire. Practitioners today often adhere strictly to this method, which is a rigid approach lacking flexibility. In general, all cold-natured substances can purge fire; how could there be a substance that cools one area but not another? The key lies in distinguishing between light/clear (Qing) and heavy/turbid (Zhuo) properties, as well as the intensity of their efficacy. When applied appropriately, the treatment will be effective.
Substances with light and clear properties are suitable for clearing heat in the upper body, such as Huangqin (Scutellariae Radix), Shihu (Dendrobii Caulis), Lianqiao (Forsythiae Fructus), and Tianhuafen (Trichosanthis Radix). Substances with heavy and turbid properties are suitable for clearing heat in the lower body, such as Zhizi (Gardeniae Fructus), Huangbai (Phellodendri Cortex), Longdan (Gentianae Radix), and Huashi (Talcum). Those with potent efficacy can clear severe heat, such as Shigao (Gypsum Fibrosum), Huanglian (Coptidis Rhizoma), Lvhui (Aloe), Kushen (Sophorae Flavescentis Radix), and Shandougen (Sophorae Tonkinensis Radix). Those with mild efficacy can clear slight heat, such as Digupi (Lycii Cortex), Xuanshen (Scrophulariae Radix), Beimu (Fritillariae Cirrhosae Bulbus), Shihu (Dendrobii Caulis), and Tongbian (Urine of Children). Used for purging, they remove heat caused by excess stagnation, such as Dahuang (Rhei Radix et Rhizoma) and Mangxiao (Natrii Sulfas). Used for promoting urination, they remove heat associated with urinary retention, such as Mutong (Akebiae Caulis), Yichen (Artemisiae Scopariae Herba), Zhuling (Polyporus), and Zexie (Alismatis Rhizoma). Used for tonifying, they remove dryness-heat due to Yin deficiency, such as Shengdi (Rehmanniae Radix), Er Dong (Tian Dong - Asparagi Radix and Mai Dong - Ophiopogonis Radix), Shaoyao (Paeoniae Radix), Lijiang (Pear Juice), and Xigancao (Glycyrrhizae Radix et Rhizoma Praeparata cum Melle). The classification of herbs by meridian in medical texts intends precisely this, though the underlying rationale is not explicitly stated.
However, if fire is severe and located in the upper part, heavy and turbid herbs may also be appropriate; if fire is mild and located in the lower part, light and clear herbs may be used. Any heat suitable for cooling treatment is Excess Heat (Shi Re). If Excess Heat is in the lower part, clearing and draining methods are naturally appropriate. If Excess Heat is in the upper part, lifting methods should not be used. Since fire inherently belongs to Yang, it should be treated from the perspective of Yin. Treating from Yin implies descending; lifting would instead follow its Yang nature. The Classic states: "For those high above, suppress them." This principle is evident. Additionally, Li Dongyuan proposed the method of "Ascending Yang and Dispersing Fire," which was established for heat generated by exterior pathogens. It cannot be conflated with internal flaming of latent fire. (Note: "Heat generated by exterior pathogens" is more accurately described as "Stagnant heat erupting externally.")