论曰∶有汗不得服麻黄，无汗不得服桂枝。切忌不得误。若寒证见风脉，风证见寒脉，
却以麻黄桂枝各半汤。古人治伤风，热多寒少，恶风，脉浮紧，无汗，用青龙汤，盖先伤风
而后伤寒，风证尚在，而寒脉已行，故有是备也。若先伤寒而后伤风，寒多热少，不烦躁，
微厥，脉当浮缓弱而自汗，即伤寒见风脉；但青龙紧暴，不若各半汤平和无悔吝也。诸经皆
仿此。
夫伤寒，始自太阳，逆传阳明，至于厥阴而止。六经既别，治法不同，太阳属膀胱，非
发汗则不愈，必用麻黄者，以麻黄生于中牟，雪积五尺，有麻黄处，雪则不聚，盖此药能通
内阳气，却外寒也。阳明属胃，非通泄则不愈，必用大黄、芒硝以利之。少阳属胆，无出入
道，柴胡与半夏能利能汗，佐以子芩，非此不解。太阴属脾，中州土也，性恶寒湿，非干姜
、白术，不能温燥。少阴属肾，性畏寒燥，非附子则不能温。厥阴属肝，藏血养筋，非温平
之药，不能润养。此经常之道也。后学不知伦类，妄意进饵，遂致错乱，诸证蜂起，夭伤人
命，可不究辨。且三阳病，汗下和解，人心知之；至太阴脾经，温燥不行，亦当温利自阳明
出，如温脾丸用大黄者是也。少阴肾经，虽用附子，复使麻黄，则知少阴亦自太阳出。厥阴
用桂，自少阳出明矣。及其二阳郁闭，皆当自阳明出。故三阴皆有下证，如少阴口燥咽干，
下利清水；太阴腹满时痛；厥阴舌卷囊缩，皆当下之。学人宜审详，不可率易投也。
论述说：有汗出的患者不得服用麻黄，无汗出的患者不得服用桂枝。这一点务必切忌，不可误用。如果寒证出现了风证的脉象，或者风证出现了寒证的脉象，则使用麻黄桂枝各半汤。古人治疗伤风病，表现为热多寒少、怕风、脉浮紧、无汗，使用大青龙汤，这是因为先受了风邪而后又受了寒邪，风证的症状还在，但寒证的脉象已经出现，所以有这样的备用方剂。如果是先受寒邪而后受风邪，寒多热少，不烦躁，四肢微冷，脉象应当是浮缓弱且自汗出，这就是伤寒病出现了风证的脉象；但是大青龙汤药性峻猛急暴，不如麻黄桂枝各半汤平和且没有后患。其他经络的病症都可以仿照这个原则处理。
伤寒病，起始于太阳经，逆向传变至阳明经，直到厥阴经才停止。六经既然区别开来，治疗方法也就不同。太阳经属于膀胱，如果不发汗就不能痊愈，必须使用麻黄的，是因为麻黄生长在中牟地区，积雪五尺厚，在有麻黄生长的地方，雪就不会积聚，大概是因为这种药物能够通达体内的阳气，抵御体外的寒邪。阳明经属于胃，如果不通泄就不能痊愈，必须使用大黄、芒硝来利导通便。少阳经属于胆，没有直接的出入通道，柴胡与半夏既能利窍又能发汗，辅以黄芩，不用这些药就不能解除病邪。太阴经属于脾，是中州的土脏，性质厌恶寒湿，不用干姜、白术，就不能温燥祛湿。少阴经属于肾，性质畏惧寒燥，不用附子就不能温补。厥阴经属于肝，主藏血和滋养筋脉，不用温和平缓的药物，就不能滋润养护。这是常规的治疗法则。后世学者不知道其中的伦理类别，随意妄进药物，导致病情错乱，各种症状蜂拥而起，残害人命，怎能不深入研究辨别呢？况且三阳病，通过发汗、攻下或和解的方法治疗，人们心里都明白；到了太阴脾经，如果温燥法不行，也应当从阳明经途径进行温利，比如温脾丸中使用大黄就是这样的例子。少阴肾经，虽然使用附子，却又配合麻黄，就知道少阴经的病也是从太阳经传出的。厥阴经使用桂枝，是从少阳经传出的，这已经很明白了。等到二阳（指阳明与太阳，或泛指阳经）郁闭不通，都应当从阳明经的途径解决。所以三阴经都有可以使用下法的证候，比如少阴经的口燥咽干、下利清水；太阴经的腹部胀满、时而疼痛；厥阴经的舌头卷缩、睾丸上缩，都应当使用下法。学习者应该仔细审察，不可草率轻易投药。
It is stated: Patients with sweating should not take Mahuang (Ephedrae Herba), and those without sweating should not take Guizhi (Cinnamon Twig). This must be strictly observed to avoid error. If a Cold syndrome presents with a Wind pulse, or a Wind syndrome presents with a Cold pulse, then Mahuang Guizhi Ban Tang (Half-Mahuang Half-Guizhi Decoction) should be used. In ancient times, for treating Shangfeng (Wind Injury) characterized by more heat than cold, aversion to wind, floating-tight pulse, and absence of sweating, Qinglong Tang (Azure Dragon Decoction) was employed. This is because the patient was first injured by Wind and subsequently by Cold; the Wind symptoms persist while the Cold pulse has appeared, hence the provision of such a formula as a backup. Conversely, if injured by Cold first and then by Wind, presenting with more cold than heat, no irritability, slight coldness in the extremities, and a floating-slow-weak pulse with spontaneous sweating, this indicates a Taiyang Cold syndrome manifesting a Wind pulse. However, Qinglong Tang is harsh and rapid in action, whereas Mahuang Guizhi Ban Tang is milder and carries no regret or adverse consequences. The principles for other meridians follow this pattern.
Shanghan (Cold Damage) begins in the Taiyang meridian, transmits inversely to the Yangming meridian, and stops at the Jueyin meridian. Since the Six Meridians are distinct, their treatment methods differ. The Taiyang belongs to the Bladder; it cannot be cured without inducing sweating. Mahuang must be used because Mahuang grows in Zhongmu, where snow accumulates five chi deep; however, where Mahuang grows, snow does not accumulate. This is likely because the herb can unblock internal Yang Qi and repel external Cold. The Yangming belongs to the Stomach; it cannot be cured without purging and draining. Dahuang (Rhei Radix et Rhizoma) and Mangxiao (Natrii Sulfas) must be used to facilitate drainage. The Shaoyang belongs to the Gallbladder, which has no direct exit or entry pathway. Chaihu (Bupleuri Radix) and Banxia (Pinelliae Tuber) can open orifices and induce sweating; when assisted by Zixin Huangqin (Scutellariae Radix), the pathogen cannot be resolved without them. The Taiyin belongs to the Spleen, the Earth organ of the Central Region, whose nature dislikes Cold and Dampness. Without Ganjiang (Zingiberis Rhizoma) and Baizhu (Atractylodis Macrocephalae Rhizoma), warmth and dryness cannot be achieved. The Shaoyin belongs to the Kidney, whose nature fears Cold and Dryness. Without Fuzi (Aconiti Lateralis Radix Praeparata), warming cannot be accomplished. The Jueyin belongs to the Liver, which stores Blood and nourishes sinews; without warm and neutral herbs, moistening and nourishing cannot occur. These are the standard principles. Later learners, ignorant of these categories, prescribe drugs arbitrarily, leading to chaotic conditions where various symptoms arise, harming lives. How can one fail to investigate and distinguish carefully? Regarding the Three Yang diseases, sweating, purging, and harmonizing methods are well understood. When it comes to the Taiyin Spleen meridian, if warming and drying methods fail, one should still employ warming and draining via the Yangming pathway, as seen in Wenpi Wan (Warm the Spleen Pill) which uses Dahuang. For the Shaoyin Kidney meridian, although Fuzi is used, the addition of Mahuang indicates that Shaoyin disease also originates from Taiyang. The use of Guizhi in Jueyin clearly indicates transmission from Shaoyang. When the Two Yangs are constrained and closed, they should all be addressed via the Yangming pathway. Therefore, all Three Yin meridians have indications for purgation: Shaoyin with dry mouth and throat, and diarrhea of clear water; Taiyin with abdominal fullness and intermittent pain; Jueyin with tongue retraction and testicular contraction—all require purgation. Students must examine these details carefully and must not administer drugs rashly.