驱邪之法，惟发表攻里二端而已。发表所以开其毛孔，令邪从汗出也。当用至轻至淡，
芳香
清冽之品，使邪气缓缓从皮毛透出，无犯中焦，无伤津液，仲景麻黄、桂枝等汤是也。然犹
恐其营中阴气，为风火所煽，而消耗于内，不能滋润和泽，以托邪于外。于是又啜薄粥，以
助胃气，以益津液，此服枝汤之良法。主发汗之方，皆可类推。汗之必资于津液如此。后世
不知，凡用发汗之方，每专用浓朴、葛根、羌活、白芷、苍术、豆蔻等温燥之药，即使其人
津液不亏，内既为风火所熬，又复为燥药所燥，则汗从何生？汁不能生，则邪无所附而出，
不但不出邪气，反为燥药鼓动，益复横肆；与正气相乱，邪火四布，津液益伤，而舌焦唇干
，便闭目赤，种种火象自生，则身愈热，神渐昏，恶症百出。若再发汗，则阳火盛极，动其
真阳，肾水来救，元阳从之，大汗上泄，亡阳之危症生矣。轻者亦成痉症，遂属坏病难治。
故用燥药发汗而杀人者，不知凡几也。此其端开于李东垣，其所着书立方，皆治湿邪之法，
与伤寒杂感无涉。而后人宗其说，以治一切外感之症，其害至今益甚。况治湿邪之法，亦以
淡渗为主，如猪苓、五苓之类，亦无以燥胜之者。盖湿亦外感之邪，总宜驱之外出，而兼以
燥湿之品，断不可专用胜湿之药，使之内攻，致邪与正争，而伤元气也。至于中寒之，亦先
以发表为主，无竟用热药以胜寒之理，必其寒气乘虚陷入，而无出路，然后以姜附回其阳，
此仲景用理中之法也。今乃以燥药发杂感之汗，不但非古圣之法，并误用东垣之法。医道失
传，只此浅近之理不知，何况深微者乎？
驱除邪气的方法，只有解表发汗和攻下里实这两类罢了。解表是为了打开毛孔，使邪气随汗液排出。应当使用性质极轻、极淡，气味芳香、清凉的药物，使邪气缓缓从皮毛透出，不侵犯中焦脾胃，不损伤津液，张仲景的麻黄汤、桂枝汤等方剂就是这样的代表。然而，仍然担心患者营分中的阴气，被风火之邪煽动，而在体内消耗，不能滋润和泽，从而托举邪气外出。于是又喝稀薄的粥，以助益胃气，以补充津液，这是服用桂枝汤的良好方法。所有主司发汗的方剂，都可以依此类推。发汗必须依赖津液的支持，道理就是这样。后世医生不了解这一点，凡是使用发汗的方剂，往往专门使用厚朴、葛根、羌活、白芷、苍术、豆蔻等温燥性质的药物。即使患者的津液原本没有亏损，内部既然已经被风火煎熬，又再受到燥药的耗伤，那么汗从哪里产生？津液不能生成，邪气就没有依附而排出的途径，不仅不能排出邪气，反而被燥药鼓动，更加猖獗肆虐；与正气相混淆，邪火四处散布，津液进一步受伤，出现舌苔焦黑、嘴唇干燥、大便闭塞、眼睛发红等种种火热征象，导致身体更加发热，神志逐渐昏迷，各种恶症纷纷出现。如果此时再强行发汗，则阳热之火盛极，扰动真阳，肾水前来救助，元阳随之流失，大汗淋漓不止，亡阳的危险病症就产生了。病情较轻的也会演变成痉病（抽搐），最终成为坏病（难治之证）。因此，使用燥药发汗而杀人的情况，不知有多少。这一弊端始于李东垣，他所著书籍中制定的方剂，都是治疗湿邪的方法，与伤寒及杂感外邪无关。而后人尊崇他的学说，用来治疗一切外感病症，其危害至今更加严重。况且治疗湿邪的方法，也以淡味渗利为主，如猪苓汤、五苓散之类，也没有用燥性药物来克制湿气的。大概湿气也是外感之邪，总宜将其驱除体外，并兼用燥湿的药物，绝不可专用胜湿（强力祛湿）的药物，使其向内攻伐，导致邪气与正气相争，从而损伤元气。至于中寒证，也应当先以解表为主，没有完全使用热药来克制寒气的道理。必须是寒气乘虚陷入体内，且没有出路时，才使用干姜、附子来回阳救逆，这是张仲景运用理中法的原则。如今却用燥药来发杂感外邪的汗，这不仅不是古代圣人的方法，更是误用了李东垣的方法。医道失传，连这种浅显的道理都不知道，何况深奥微妙的理论呢？
The methods for expelling pathogenic factors consist only of two categories: releasing the exterior (Jie Biao) and purging the interior (Gong Li). Releasing the exterior aims to open the pores, allowing pathogens to exit through sweat. One should employ substances that are extremely light, bland, aromatic, and cooling, so that pathogenic factors slowly permeate out from the skin and hair without invading the Middle Jiao (Middle Burner) or damaging Body Fluids (Jin Ye). The formulas such as Mahuang Tang (Ephedra Decoction) and Guizhi Tang (Cinnamon Twig Decoction) by Zhang Zhongjing exemplify this approach. However, there is still a concern that the Yin Qi within the Ying (Nutritive) level may be fanned by Wind-Fire, leading to internal consumption, failing to moisten and nourish, and thus unable to support the expulsion of pathogens outward. Therefore, drinking thin congee (porridge) is recommended to assist Stomach Qi and replenish Body Fluids; this is an excellent method for taking Guizhi Tang. This principle can be extrapolated to all formulas primarily intended for inducing sweating. Inducing sweating necessarily relies on Body Fluids, as demonstrated here.
Later generations, unaware of this, often exclusively use warm and drying herbs such as Houpo (Magnolia Bark), Gegen (Kudzu Root), Qianghuo (Notopterygium Rhizome), Baizhi (Angelica Dahurica), Cangzhu (Atractylodes Rhizome), and Doukou (Black Cardamom) in sweating formulas. Even if a patient's Body Fluids were not initially deficient, having already been simmered internally by Wind-Fire, they are further dried by these warming-drying drugs. Consequently, where would sweat come from? If fluids cannot be generated, pathogens have no medium to attach to and exit. Instead of expelling pathogens, the drying drugs agitate them, causing them to become more rampant; they mix with Healthy Qi (Zheng Qi), spreading Pathogenic Fire everywhere, further injuring Body Fluids, resulting in symptoms such as a scorched tongue, dry lips, constipation, and red eyes. Various fire-like manifestations arise spontaneously, causing the body temperature to rise further and consciousness to gradually cloud, leading to the emergence of various severe syndromes. If sweating is induced again at this stage, Yang-Fire reaches its peak, disturbing the True Yang (Zhen Yang). Kidney Water comes to rescue, and Yuan Yang (Original Yang) follows it out; excessive sweating ensues, giving rise to critical conditions of Yang Collapse (Wang Yang). In milder cases, it may develop into Jing Syndrome (Spasm/Convulsion), eventually becoming a Huai Bing (Ruined Disease/Difficult-to-Treat Condition). Thus, countless deaths have occurred due to the use of drying drugs to induce sweating.
This trend originated with Li Dongyuan. The formulas he prescribed in his writings were methods for treating Dampness Pathogens, unrelated to Shanghan (Cold Damage) or miscellaneous external infections. Later generations followed his theory, applying it to all external infection syndromes, and the harm has intensified to this day. Moreover, the method for treating Dampness primarily involves bland leaching/draining agents, such as Zhuling Tang (Polyporus Decoction) and Wuling San (Five-Ingredient Powder with Poria), none of which rely on drying drugs to overcome dampness. Generally, Dampness is also an external pathogen; it should always be driven outwards, possibly combined with damp-drying agents. It is absolutely inadvisable to exclusively use strong damp-resisting drugs, which would cause inward attack, leading to conflict between Pathogens and Healthy Qi, thereby damaging Original Qi.
Regarding Cold Invasion (Zhong Han), treatment should first focus on releasing the exterior. There is no rationale for solely using hot drugs to overcome cold. Only when Cold Qi sinks into the interior due to deficiency and lacks an outlet should one use Jiang (Zingiberis Rhizoma) and Fu Zi (Aconiti Lateralis Radix Praeparata) to restore Yang. This is the principle behind Zhang Zhongjing’s use of Lizhong Fa (Regulating the Middle Method). Today, however, drying drugs are used to induce sweating for miscellaneous external infections. This is not only contrary to the methods of ancient sages but also a misuse of Li Dongyuan’s methods. The medical Dao has been lost; if even such superficial principles are unknown, how much more so the profound and subtle theories?