时疫为热证，未有不当清者也。其在表宜汗，使热从汗泄，汗法亦清法也；在里宜下，使热从下泄，下法亦清
法也。若在表已得汗而热不退，在里已下而热不解，或本来有热无结，则惟以寒凉直折以清其热而已，故清法可济
汗、下之不逮，三者之用，可合而亦可分。时疫当清者十之六、七，则清法不可不细讲也。
凡清热之要，在视热邪之浅、深。热之浅者在营卫，以石膏、黄芩为主，柴胡、葛根为辅；热之深者在胸膈，
花粉、知母、蒌仁、栀子、豆豉为主。热在肠胃者，当用下法，不用清法，或下而兼清亦可。热入心包者，黄连、
犀角、羚羊角为主。热直入心脏，则难救矣，用牛黄犹可
十中救一，须用至钱许，少则无济，非若小儿惊风诸方，每用分许即可有效。
当清诸证，详列于下∶
热在营卫证∶身热汗自出，不恶寒反恶热，身重，头
面项红肿，周身红肿，斑疹，鼻孔干，唇燥，烦躁，遗尿，舌苔白。
热在胸膈证∶身热反减，渴，呕，咳，咽干，谵语，多言，胸前红肿，舌苔浓白。
热在肠胃证∶便血，便脓血。余悉见下证条中。
热在心包及心证∶狂，昏沉，多睡，舌黑。
寒热并用之谓和，补泻合剂之谓和，表里双解之谓和，平其亢厉之谓和。所谓寒热并用者，因时疫之热夹有
他邪之寒，故用此法以和之也。凡方中有黄连与生姜同用，黄芩与半夏同用，石膏与苍术同用，知母与草果同用
者皆是。所谓补泻合用者，因时疫之邪气实，人之正气虚，故用此法以和之。凡方中有参、 、归、芍与硝、
黄、枳、朴同用者是。所谓表里双解者，因疫邪既有表证，复有里证，故用此法以和之。凡方中有麻、葛、羌、
防、柴、前与硝、黄、栀、芩、苓、泽、枳、朴合用者是。所谓平其亢厉者，因时疫之大势已去，而余邪未解，
故用此法以和之，或用下法而小其剂料，缓其时日；或用清法而变其汤剂，易为丸散者皆是。凡此和法，虽名为
和，实寓有汗、下、清、补之意，疫邪尤有宜和者。
凡热不清，用清凉药不效，即当察其热之所附丽。盖无所附丽之热，为虚而无形之气。如盛夏炎蒸，遇风雨即
解，故人身之热，气清即退。有所附丽之热，为实而有物。如洪炉柴炭，虽沃以水，尤有沸腾之忧，必撤去柴炭
而热始退。凡热之所附丽，非痰即滞，非滞即血，径清其热，不去其物，未能有效。必视其附丽何物，于清热诸方
加入何药，效始能捷。此和法之精微神变者也。
宜和之证，详列于下∶寒热往来，盗汗，口苦，咽干，头眩，舌强，渴，胸胁满，耳聋，小便黄，呕吐下利
而心下痛，口干舌强而恶寒，大小便闭而寒热，痞满而悸，二便自利而舌苔，形体瘦损而舌苔。凡此表、里、虚、
实、寒、热相兼者不可枚举，引此数端，可以类推，其有似和而实非和证者，详后辨似条。
Plague is a heat syndrome, and there is none that does not require the Clearing Method (Qing Fa). If the pathogen is in the exterior, sweating should be induced to allow heat to escape via sweat; the Sweating Method (Han Fa) is also a form of Clearing. If the pathogen is in the interior, purgation should be used to allow heat to escape via defecation; the Purgative Method (Xia Fa) is also a form of Clearing. However, if sweating has been performed in the exterior but heat persists, or purgation has been performed in the interior but heat remains unresolved, or if there was originally heat without accumulation/stagnation, then only cold-cooling herbs should be used directly to suppress and clear the heat. Thus, the Clearing Method can supplement the deficiencies of the Sweating and Purgative Methods; the functions of these three methods can be combined or used separately. In plague cases requiring clearing, six or seven out of ten do so, making it essential to study the Clearing Method in detail.
The key to clearing heat lies in observing the depth of the heat pathogen. When heat is shallow, residing in Ying and Wei (Nutritive and Defensive Qi), Shi Gao (Gypsum Fibrosum) and Huang Qin (Scutellariae Radix) are the principal herbs, with Chai Hu (Bupleuri Radix) and Ge Gen (Puerariae Lobatae Radix) as auxiliaries. When heat is deep, located in the chest and diaphragm, Hua Fen (Trichosanthis Radix), Zhi Mu (Anemarrhenae Rhizoma), Gua Lou Ren (Trichosanthis Semen), Zhi Zi (Gardeniae Fructus), and Dou Chi (Sojae Preparata) are the principal herbs. If heat is in the stomach and intestines, the Purgative Method should be used rather than the Clearing Method, or purgation combined with clearing may be employed. If heat enters Xin Bao (Pericardium), Huang Lian (Coptidis Rhizoma), Xi Jiao (Rhinocerotis Cornu - *note: substitute with Buffalo Horn Shui Niu Jiao in modern practice*), and Ling Yang Jiao (Saiga Tataricae Cornu) are the principal herbs. If heat directly enters the Heart, it is difficult to save; using Niu Huang (Calculus Bovis) might save one in ten, requiring a dose of approximately one qian (approx. 3-5g); a smaller dose is ineffective, unlike formulas for infantile convulsions where a few fen (approx. 0.3-0.5g) suffice.
The various syndromes suitable for the Clearing Method are listed below:
Heat in Ying and Wei Syndrome: Fever with spontaneous sweating, aversion to cold replaced by aversion to heat, heaviness of the body, redness and swelling of the head, face, and neck, generalized redness and swelling, macules and papules, dry nostrils, dry lips, irritability, enuresis, white tongue coating.
Heat in Chest and Diaphragm Syndrome: Body heat seemingly decreases, thirst, vomiting, cough, dry throat, delirious speech, excessive talking, redness and swelling of the chest, thick white tongue coating.
Heat in Stomach and Intestines Syndrome: Hematochezia (blood in stool), dysentery (pus and blood in stool). Other symptoms are detailed in the entries for the Purgative Method.
Heat in Pericardium and Heart Syndrome: Mania, lethargy/coma, excessive sleep, black tongue.
Using cold and hot herbs together is called Harmonizing (He Fa); combining tonification and purgation is called Harmonizing; resolving both exterior and interior simultaneously is called Harmonizing; pacifying excessive intensity is called Harmonizing. The term "using cold and hot together" applies because plague heat often accompanies cold from other pathogens, thus this method harmonizes them. Examples include formulas containing Huang Lian with Sheng Jiang (Zingiberis Rhizoma Recens), Huang Qin with Ban Xia (Pinelliae Rhizoma), Shi Gao with Cang Zhu (Atractylodis Rhizoma), and Zhi Mu with Cao Guo (Tsaoko Fructus). The term "combining tonification and purgation" applies because plague pathogens are excess while the body's righteous qi is deficient, thus this method harmonizes them. Examples include formulas containing Ren Shen (Ginseng Radix et Rhizoma), [missing character, likely Ginseng or similar], Dang Gui (Angelicae Sinensis Radix), Bai Shao (Paeoniae Radix Alba) combined with Mang Xiao (Natrii Sulfas), Da Huang (Rhei Radix et Rhizoma), Zhi Shi (Aurantii Fructus Immaturus), and Hou Po (Magnoliae Officinalis Cortex). The term "resolving exterior and interior simultaneously" applies because epidemic pathogens present both exterior and interior syndromes, thus this method harmonizes them. Examples include formulas combining Ma Huang (Ephedrae Herba), Ge Gen, Qiang Huo (Notopterygii Rhizoma et Radix), Fang Feng (Saposhnikoviae Radix), Chai Hu, Qian Hu (Peucedani Radix) with Mang Xiao, Da Huang, Zhi Zi, Huang Qin, Fu Ling (Poria), Ze Xie (Alismatis Rhizoma), Zhi Shi, and Hou Po. The term "pacifying excessive intensity" applies because the main force of the plague has subsided but residual pathogens remain, thus this method harmonizes them. This includes using the Purgative Method with reduced dosage and slower administration, or using the Clearing Method but changing the decoction into pills or powders. Although these Harmonizing methods are named "Harmonizing," they actually contain elements of Sweating, Purgation, Clearing, and Tonification; plague pathogens particularly have indications for Harmonizing.
When heat cannot be cleared and cooling herbs are ineffective, one must examine what the heat is attached to. Heat without attachment is deficient and formless qi. Like the intense heat of midsummer dissipating upon wind and rain, human body heat retreats when qi becomes clear. Heat with attachment is excess and substantial. Like charcoal in a furnace, even if water is poured on it, boiling continues until the charcoal is removed. Whatever heat attaches to is either phlegm or stagnation, or stagnation or blood stasis. Directly clearing heat without removing the attached substance is ineffective. One must identify the attached substance and add appropriate herbs to the clearing formulas for rapid efficacy. This represents the subtle and miraculous variations of the Harmonizing Method.
Syndromes suitable for Harmonizing are listed below: Alternating chills and fever, night sweats, bitter taste in the mouth, dry throat, dizziness, stiff tongue, thirst, fullness in the chest and hypochondrium, deafness, yellow urine, vomiting and diarrhea with epigastric pain, dry mouth and stiff tongue with aversion to cold, constipation and urinary retention with alternating chills and fever, stuffiness and fullness with palpitations, normal bowel and bladder movements with abnormal tongue coating, emaciation with abnormal tongue coating. These combinations of exterior/interior, deficiency/excess, cold/heat are too numerous to list; citing these few examples allows for deduction. Cases that appear to be Harmonizing but are not, are detailed in the following section on Differentiating Similarities.