寒热真假，不可不知，正治逆治，岂可不辨！假如热病服寒药热不退，后用热
药而热方退；假如寒病服热药而寒不退，后用寒药而寒方退者，此为从治也。从治者，反攻也。治
热病以寒药而愈，治寒病以热而愈者，逆治也。逆治者，正治也。且反攻之法，人亦难晓者，多。
如寒病服寒药而愈者，此阳极变阴，热极反得水化也。热病服热药而愈者，此阴极变阳，寒极反得
火化也。盖物极则反也。
标本逆从之既明，五剂之药须用识。且如，表汗用麻黄，无葱白不发。吐痰用瓜蒂，无豆豉不
涌。去实热用大黄，无枳实不通。温经用附子，无干姜不热，甚则以泥清水加葱白煎之。竹沥，无
姜汁不能行经络。蜜导，无皂角不能通秘结。非半夏、姜汁，不能止呕吐。非人参、竹叶，不能止
虚烦。非小柴胡，不能和解表里。非五苓散，不能通利小便。非天花粉、干葛，不能消渴解肌。非
人参、麦门冬、五味，不能生脉补元。非犀角、地黄，不能止上焦之吐衄。非桃仁承气，不能破下
焦之瘀血。非黄 、桂枝，不能实表间虚汗。非茯苓、白术，不能去湿助脾。非茵陈，不能除黄胆。
非承气，不能制定发狂。非枳、桔，不能除痞满。非陷胸，不能开结
胸。非羌活冲和，不能治四时之感冒身疼。非人参败毒，不能治春瘟。非四逆，不能救阴厥。非人
参白虎，不能化斑。非理中、乌梅，不能治蛔厥。非桂枝、麻黄，不能除冬月之恶寒，热随汗解。
非姜附汤，不能止阴寒之泄利。非大柴胡，不能去实热之妄言。阴阳咳嗽，上气喘急，用加减小青
龙，分表里而可汗下。此伤寒用药之大法也。
The distinction between true and false cold and heat patterns must be understood, and the differentiation between direct treatment (Zheng Zhi) and indirect treatment (Ni Zhi) cannot be ignored! For instance, if a heat disease does not improve after administering cold-natured herbs, but improves only after switching to hot-natured herbs; or if a cold disease does not improve after administering hot-natured herbs, but improves only after switching to cold-natured herbs—this is called "Cong Zhi" (Following Treatment). "Cong Zhi" refers to "Fan Gong" (Counter-attack/Indirect Treatment). Conversely, curing a heat disease with cold-natured herbs and curing a cold disease with hot-natured herbs is called "Ni Zhi" (Opposing Treatment). "Ni Zhi" is synonymous with "Zheng Zhi" (Direct/Standard Treatment). Moreover, the principles of counter-attack are often difficult for people to comprehend. For example, when a disease presenting as cold is cured by cold-natured herbs, it indicates that extreme Yang transforms into Yin (True Heat, False Cold), where extreme heat is resolved by water-like (cold) properties. When a disease presenting as heat is cured by hot-natured herbs, it indicates that extreme Yin transforms into Yang (True Cold, False Heat), where extreme cold is resolved by fire-like (hot) properties. This is because things reverse when they reach their extreme.
Once the principles of root and branch, opposition and following are clear, one must possess knowledge in applying the five types of formulations. For example, to induce sweating for exterior release, Ephedrae Herba (Mahuang) is used, but without Allii Fistulosi Bulbus (Congbai), dispersion will not occur. To induce vomiting for phlegm expulsion, Citrulli Semen (Gua Di) is used, but without Sojae Preparata (Dou Chi), eruption will not happen. To purge excess heat, Rhei Radix et Rhizoma (Dahuang) is used, but without Aurantii Fructus Immaturus (Zhishi), unblocking will not take place. To warm the meridians, Aconiti Lateralis Radix Praeparata (Fuzi) is used, but without Zingiberis Rhizoma (Ganjiang), heat will not be generated; in severe cases, processed Aconite is boiled in clear water with Allii Fistulosi Bulbus. Arum Rhizoma juice (Zhuli) cannot circulate through the meridians without Zingiberis Juice (Jiangzhi); Honey suppositories (Midao) cannot relieve constipation without Gleditsiae Sinensis Spina (Zaojiao). Without Pinelliae Rhizoma (Banxia) and Zingiberis Juice, vomiting cannot be stopped; without Ginseng Radix (Renshen) and Phyllostachys Viridis Caulis (Zhuyeqian), deficiency-related vexation cannot be alleviated; without Xiao Chai Hu Tang (Minor Bupleurum Decoction), harmonizing the interior and exterior is impossible; without Wu Ling San (Five-Ingredient Powder with Poria), promoting urination is ineffective; without Trichosanthis Radix (Tianhuafen) and Puerariae Lobatae Radix (Gegen), thirst relief and muscle-layer resolution cannot be achieved; without Ginseng Radix, Ophiopogonis Radix (Maigendong), and Schisandrae Fructus (Wuweizi), generating the pulse and tonifying the primal Qi is unattainable; without Rhinocerotis Cornu (Xijiao) and Rehmanniae Radix (Dihuang), stopping epistaxis and hematemesis from the Upper Jiao is impossible; without Tao Ren Cheng Qi Tang (Peach Kernel and Rhubarb Decoction), breaking down blood stasis in the Lower Jiao cannot be accomplished; without Astragali Radix (Huangqi) and Cinnamomi Ramulus (Guizhi), securing the exterior and stopping deficiency sweating is not possible; without Poria (Fuling) and Atractylodis Macrocephalae Rhizoma (Baizhu), dispelling dampness and assisting the Spleen is ineffective; without Coptidis Rhizoma (Yinchen is actually Artemisiae Scopariae Herba, Yichen) [Correction: Yin Chen Hao], clearing jaundice is impossible; without Cheng Qi Tang variants, controlling mania cannot be formulated; without Aurantii Fructus (Zhike) and Platycodonis Radix (Jiegeng), removing fullness and stagnation is not feasible; without Xiong Xiong Tang (Chest-Harmonizing Decoction), opening chest-knotting is impossible; without Qiang Huo Chong He Tang (Notopterygii Root Harmonious Decoction), treating body aches from seasonal colds is not possible; without Renshen Bai Du San (Ginseng Detoxification Powder), treating spring plagues is ineffective; without Si Ni Tang (Four Reversal Decoction), saving from Yin collapse is impossible; without Renshen Bai Hu Tang (Ginseng White Tiger Decoction), resolving macules is unattainable; without Li Zhong Wan combined with Vitis Vinifera Seed (Wumei), treating ascariasis-induced reversal cold is not effective; without Guizhi Tang and Mahuang Tang, eliminating winter aversion to cold and allowing heat to resolve with sweat is impossible; without Jiang Fu Tang (Ginger and Aconite Decoction), stopping diarrhea due to Yin-cold is not possible; without Da Chai Hu Tang (Major Bupleurum Decoction), removing delirium caused by excess heat is ineffective; for yin-yang cough and rapid upper-body breathing, Jia Jian Xiao Qing Long Tang (Modified Minor Blue Dragon Decoction) is used to differentiate the interior and exterior, thereby permitting sweating or purging methods. These constitute the major principles of herb usage in treating Shang Han (Cold Damage).