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。
时疫属于热证，没有不应当使用清法的。病邪在表应当用汗法，使热邪随汗液排出，汗法也是清法的一种；病邪在里应当用下法，使热邪从大便排出，下法也是清法的一种。如果在表已经发汗但热不退，在里已经攻下但热不解，或者原本就有热邪而没有积滞结聚，那么就只用寒凉药物直接折损热势以清除热邪。因此，清法可以弥补汗法和下法的不足，这三种方法的作用，既可以合用也可以分开使用。时疫病中需要清法的占十分之六、七，所以清法不可不详细研究。
凡清热的关键，在于观察热邪的浅深。热邪浅在营卫（运行于体表及脏腑之间的气与血），以石膏、黄芩为主药，柴胡、葛根为辅药；热邪深陷在胸膈，以天花粉、知母、瓜蒌仁、栀子、豆豉为主药。热邪在肠胃者，应当用下法，不用清法，或者攻下兼清也可。热邪侵入心包（心之外围）者，以黄连、犀角、羚羊角为主药。热邪直入心脏，就难以救治了，使用牛黄还可以十中救一，必须用到一钱左右，用量少了就没有帮助，不像治疗小儿惊风的方剂，每用几分就可以见效。
热在营卫证：身体发热，自然出汗，不怕冷反而怕热，身体沉重，头面项部红肿，周身红肿，出现斑疹，鼻孔干燥，嘴唇燥裂，烦躁不安，遗尿，舌苔白。
热在胸膈证：身体发热反而减轻，口渴，呕吐，咳嗽，咽喉干燥，说胡话，多言，胸前红肿，舌苔厚白。
寒热并用的称为和法，补泻合剂的称为和法，表里双解的称为和法，平抑亢盛剧烈的称为和法。所谓寒热并用，是因为时疫的热邪夹杂有其他邪气的寒性，所以用此法来调和它。凡是方剂中有黄连与生姜同用，黄芩与半夏同用，石膏与苍术同用，知母与草果同用的，都是这种情况。所谓补泻合用，是因为时疫的邪气实盛，人的正气虚弱，所以用此法来调和。凡是方剂中有参、[此处原文缺字，通常指人参或党参等补气药]、当归、芍药与芒硝、大黄、枳实、厚朴同用的，就是这种情况。所谓表里双解，是因为疫邪既有表证，又有里证，所以用此法来调和。凡是方剂中有麻黄、葛根、羌活、防风、柴胡、前胡与芒硝、大黄、栀子、黄芩、茯苓、泽泻、枳实、厚朴合用的，就是这种情况。所谓平抑亢盛剧烈，是因为时疫的大势已去，而余邪未解，所以用此法来调和，或者用下法但减小剂量，延缓时间；或者用清法但改变汤剂形式，改为丸散剂，都是这种情况。所有这些和法，虽然名为和，实际上蕴含了汗、下、清、补的意思，疫邪中尤其有适合用和法的。
凡是热邪不清，使用清凉药无效，就应当考察热邪依附的是什么。那种无所依附的热，是虚而无形的热气。就像盛夏炎热蒸腾，遇到风雨就消散，所以人身的热气，气机清爽就会退去。有所依附的热，是实而有形之物。就像洪炉中的木炭，即使泼水，仍有沸腾的担忧，必须撤去木炭热才会退去。凡是热邪所依附的，不是痰就是积滞，不是积滞就是瘀血，直接清热，不去除依附之物，不能见效。必须看它依附的是什么物，在清热诸方中加入相应的药物，疗效才能迅速。这是和法精微神妙的变化之处。
适宜用和法的证候，详细列举如下：寒热往来，盗汗，口苦，咽干，头晕目眩，舌体僵硬，口渴，胸胁胀满，耳聋，小便黄，呕吐腹泻且心下疼痛，口干舌硬且恶寒，大小便闭塞且寒热交替，痞满且心悸，二便自利且舌苔异常，形体消瘦且舌苔异常。以上这些表、里、虚、实、寒、热相兼的情况不可枚举，列举这几端，可以类推，其中有看似和法实则非和证的，详见后文辨似条目。
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.