李 曰。阴阳病者为虚。不病者为实。表病里和。则邪出于外而为阳虚阴盛。故发表不远热。
而用辛甘之剂。所以扶阳也。里病表和。则邪入于内而为阴虚阳盛。故攻里不远寒。而用辛苦之药。
所以扶阴也。若阴经自受寒邪。则为脏病。设阴阳气将脱。急宜辛热回阳抑阴。故曰。桂枝下咽。
阳盛则毙。承气入胃。阴盛乃亡。实实虚虚。损不足而益有余。医杀之耳。此汗下之枢机。
汗、吐、下、温、解五法。各有不同。汗。有大汗发表。微汗解肌。以别重轻。下。有急下。
少与微和。渗利以厘清浊。吐。有宣涌探引。或只宽利而不敢吐者。温。有兼补者。和解。则一
而已。或曰。传寒无补法。热气得补复盛。更复下之。是重困也。惟虚烦里寒阴症。不在此例。得
中者立法动中肯綮。太过者粗工猛进。不及者中工从缓从轻。凡伤寒汗下药。一服中病即止。不必
尽剂。与杂病不同。伤寒不过汗吐下三症。若用之得当。有何传变。全在医者精以审处之耳。有暂
补法。凡尺寸迟弱。血少也。不问风寒初症杂症。俱忌汗吐下。宜先以小建中汤。或黄 建中汤救
之。脉如素实者。小柴胡汤亦可。俟脉不迟。方可施用。伤寒题目未定之时。不知有无风湿劳役痰
食等项相兼。似是而非。最宜详辨。故不知者宁可不治。班固有言曰。有病不治得中医。倘一药之
误。悔将何及。有不可吐者。膈上寒饮干呕。少阴病也。四肢冷。胃亏也。脉微。下虚也。误吐内
烦。损伤元气。遂致不救者有之。若应吐而反温之。则毒瓦斯郁结于胃而为发狂等症。
鳌按。楼氏温法。李氏补法。必精审详确。如果病属三阴。为必当温。且果初病脉弱。为有可
补者方可根据法治之。不然。误温误补。为害不浅。故特表出。阅者宜致思焉。毋徒一例视之。遂昧
焉以为成法而用之也。
李氏说：阴阳经受邪的病证属于虚证，未受邪的属于实证。表部受病而里部调和，则邪气向外发散，表现为阳虚阴盛，因此解表发汗不宜远离温热之性，而使用辛甘性质的药物，以此来扶助阳气。里部受病而表部调和，则邪气向内深入，表现为阴虚阳盛，因此攻下里实不宜远离寒凉之性，而使用辛苦性质的药物，以此来扶助阴气。如果是阴经直接感受寒邪，则导致脏腑病变；假如阴阳之气即将脱失，急需使用辛热药物来回阳救逆、抑制阴寒，所以说：“桂枝汤服下，若遇阳盛之体则会致死；承气汤入胃，若遇阴盛之体则会亡命。”这是使实证更实、虚证更虚，损害不足的正气而增加有余的邪气，是医生杀人罢了。这是运用汗法与下法的关键枢机所在。
汗法、吐法、下法、温法、和解法这五种治法，各有不同。汗法中，有大汗以发散表邪，微汗以解除肌表之邪，以此区别病情的轻重。下法中，有急下攻逐，也有少量给予以轻微调和，还有渗湿利水以分清浊。吐法中，有宣通涌吐、探引排邪，或者只是宽胸利膭而不敢用吐法的。温法中，有兼用补益的。和解法则只有一种。
有人说：传变而来的寒证没有补法，热气得到补益会重新旺盛，再进一步攻下，这是使病情更加困顿。只有虚烦、里寒、阴证的情况，不在此例之中。掌握适中原则的人，立法能够切中要害；过于激进的人是粗疏的工匠猛力进击；力度不够的人是中等水平的工匠从缓从轻处理。凡是治疗伤寒的汗法和下法，一服药如果病愈就立即停止，不必服完全部药量，这与治疗杂病不同。伤寒不过就是汗、吐、下三种症候，如果使用得当，有什么样的传变呢？全在于医生精准审慎地处置罢了。
还有暂时性的补法。凡是寸关尺三部脉象迟而弱，说明血少。不论风寒初起的症状还是杂病，都忌用汗、吐、下法，适宜先用小建中汤或黄芪建中汤来救治它。如果脉象像平时一样充实有力，小柴胡汤也可以适用。等到脉象不再迟滞，才可以施用其他治法。在伤寒的题目尚未确定之时，不知道是否有风湿、劳役、痰饮、食积等项相兼，似是而非，最应当详细辨别。所以不知者宁可暂时不治，正如班固所说：“有病不治，可得一个中等水平的医生评价。”倘若有一味药的失误，后悔又怎么来得及呢？
有不可用吐法的情况：膈上有寒饮导致干呕，这是少阴病；四肢寒冷，是胃气亏损；脉象微弱，是下焦虚弱。误用吐法会导致内烦，损伤元气，于是导致无法救治的情况时有发生。如果应当用吐法却反而用温法，则毒瓦斯郁结在胃中，从而引发发狂等症状。
沈金鳌按语：楼氏的温法、李氏的补法，必须精准审慎、详细确切。如果病属三阴经，确实是应当温补的，并且确实是在初病时脉象微弱，是有可补之处，才可以依据此法治疗。否则，误用温法或补法，危害不浅。所以特意列出，阅读者应当深思，不要简单地一概视之，从而蒙昧地将其当作固定成法而使用。
Li stated: Diseases affecting the Yin and Yang meridians belong to deficiency patterns, while those not affected belong to excess patterns. When the exterior is diseased but the interior is harmonious, the pathogenic factor emerges outward, manifesting as Yang deficiency and Yin abundance. Therefore, releasing the exterior should not avoid heat, utilizing acrid and sweet agents to support Yang. When the interior is diseased but the exterior is harmonious, the pathogenic factor enters inward, manifesting as Yin deficiency and Yang abundance. Therefore, purging the interior should not avoid cold, utilizing acrid and bitter drugs to support Yin. If the Yin meridians directly contract cold pathogens, it results in Zang organ disease. If Qi of Yin and Yang is on the verge of collapse, urgent use of acrid-hot drugs is required to restore Yang and suppress Yin. Thus it is said: "If Guizhi Tang (Cinnamon Twig Decoction) is swallowed when Yang is abundant, death ensues; if Chengqi Tang (Gut-Purging Decoction) enters the stomach when Yin is abundant, demise follows." This constitutes making the excess more excessive and the deficiency more deficient, damaging what is insufficient and benefiting what is redundant; this is a physician killing the patient. This is the pivotal mechanism for employing sweating and purging methods.
The five methods—sweating, vomiting, purging, warming, and harmonizing—each have distinct characteristics. Sweating includes profuse sweating to release the exterior and mild sweating to resolve the muscle layer, distinguishing severity. Purging includes urgent purging, small doses for mild harmonization, and diuresis to separate clear from turbid. Vomiting includes promoting surging and probing extraction, or merely widening the chest without daring to induce vomiting. Warming includes methods that combine tonification. Harmonizing consists of only one approach.
Some say: For transmitted cold, there is no tonification method; heat qi, upon receiving tonification, will flourish again, and subsequent purging would further distress the condition. Only cases of empty irritability, interior cold, and Yin patterns are excluded from this rule. Those who grasp the mean establish laws hitting the vital points; those who are excessive act like crude craftsmen advancing aggressively; those who fall short act like average craftsmen proceeding slowly and mildly. In treating Taiyang disease with sweating and purging methods, stop after one dose if the illness responds; do not finish the entire prescription, which differs from treating miscellaneous diseases. Taiyang disease involves only sweating, vomiting, and purging symptoms; if applied correctly, what transmission could occur? It entirely depends on the physician's precise and prudent handling.
There is also a temporary tonification method. Whenever the Cun, Guan, and Chi pulses are slow and weak, indicating blood deficiency, regardless of whether it is an initial Wind-Cold syndrome or a miscellaneous disease, sweating, vomiting, and purging are contraindicated. One should first use Xiaojianzhong Tang (Minor Construct the Middle Decoction) or Huangqi Jianzhong Tang (Astragalus Decoction to Minor Construct the Middle) to rescue the condition. If the pulse resembles its usual robust state, Xiaochaihu Tang (Minor Bupleurum Decoction) may also be applicable. Wait until the pulse is no longer slow before applying other treatments. When the diagnosis of Taiyang disease is undetermined, and it is unknown whether Wind-Dampness, labor injury, phlegm, or food stagnation are concurrent, presenting as similar yet different, careful differentiation is essential. Therefore, ignorance warrants abstaining from treatment. As Ban Gu stated: "Not treating a disease can earn the rating of an average physician." If a single herb causes error, how can regret suffice?
There are conditions where vomiting is contraindicated: Cold fluid retention above the diaphragm causing dry heaving indicates Shaoyin disease; cold limbs indicate Stomach deficiency; a faint pulse indicates lower deficiency. Erroneous vomiting leads to internal irritability, damaging Yuan Qi, potentially leading to untreatable states. Conversely, if vomiting is indicated but warming is used instead, toxic factors stagnate in the Stomach, resulting in mania and other symptoms.
Shen Jin'ao notes: Lou's warming method and Li's tonification method must be precise, prudent, detailed, and accurate. Only if the disease belongs to the Three Yin meridians and truly requires warming, and if indeed the pulse is weak at onset, indicating potential for tonification, should these methods be followed. Otherwise, erroneous warming or tonification causes significant harm. Thus, they are specifically highlighted for readers to contemplate deeply, avoiding simplistic application as fixed formulas.