按∶《伤寒论》曰∶太阳病，头痛，发热，恶寒，体痛，呕逆，脉阴阳俱紧，无汗而喘者，名
为伤寒，麻黄汤主之。曰∶太阳病，头痛，发热，汗出，恶风，脉缓者，名为中风，桂枝汤主之。
此以无汗脉紧者为伤寒，故用麻黄汤；有汗脉缓者为中风，故用桂枝汤，是其辨也。又《论》曰∶
桂枝本为解肌，若其人脉浮紧，发热汗不出者，不可与也，常须识此，勿令误也。然何以又曰∶太
阳病外证未解，脉浮弱者，当以汗解，宜桂枝汤。阳明病，日晡所发热，脉虚浮者，宜发汗，发汗
宜桂枝汤，是岂桂枝为止汗者耶？但麻黄汤无芍药，而用麻黄，桂枝汤无麻黄，而用芍药，盖桂枝
性散，芍药性敛，以芍药从桂枝，则桂枝不峻，以桂枝从芍药，则芍药不寒。然以芍药之懦，终不
胜桂枝之勇，且芍药能滋调营气，适足为桂枝取汗之助，故桂枝汤亦是散剂，但麻黄汤峻，
而桂枝汤缓耳。故凡寒邪深固者，恐服桂枝不能解表，则反以助热，所以脉紧无汗者，宜麻黄不宜
桂枝；若脉浮缓有汗，或浮弱者，以其风邪尚浅，宜桂枝不宜麻黄也。此麻黄汤为发表之第一，而
桂枝汤则解表之次者也。今时医不能察此，但闻汗不出者，不可与桂枝，便谓桂枝能止汗，误亦甚
矣，而不知止汗在芍药，不在桂枝也。但桂枝性温，能强卫气，如《内经》曰∶阴气有余，为多汗
身寒。仲景曰∶极寒反汗出者，此亡阳而汗也，助阳乃可以止汗，则正宜用桂枝矣。又《伤寒论》
以太阳病无汗脉紧者为伤寒，汗出脉缓者为中风，此风寒之辨也。然大青龙汤证治曰∶太阳中风，
脉浮紧，发热恶寒，身疼痛，不汗出而烦躁者，大青龙汤主之。是岂非太阳中风亦有脉紧无汗者耶
？可见风之与寒，本不相远，但风邪浅而寒邪深耳，浅属阳而深属阴耳。且近见外感寒邪者，率
皆伤寒发热脉紧无汗等证，至于中风一证，谓其脉缓有汗，而复发热者，其病本不多见，即有之，
亦必外因者少，而内因者多也。倘学人以风寒二字，及麻黄桂枝二汤，必欲分其阴阳同异，而执以
为辞，则失之远矣。本门前卷有风寒辨，宜并察之。
按语：《伤寒论》中说：太阳病（太阳经受邪所致的病证），出现头痛、发热、恶寒（怕冷）、身体疼痛、呕吐气逆，脉象寸关尺三部都紧，无汗且气喘的，称为伤寒，用麻黄汤主治。又说：太阳病，出现头痛、发热、出汗、怕风，脉象缓弱的，称为中风，用桂枝汤主治。这里是以无汗、脉紧作为伤寒的特征，所以用麻黄汤；以有汗、脉缓作为中风的特征，所以用桂枝汤，这就是两者的区别。
另外，《伤寒论》还说：桂枝原本是用来解除肌表的邪气，如果病人脉象浮紧，发热但不出汗，就不能给服用桂枝汤，必须时刻记住这一点，不要弄错了。然而为什么又说：太阳病表证未解，脉象浮而弱的，应当用发汗法治疗，适宜用桂枝汤。阳明病（阳明经受邪所致的病证），在下午申时左右发热，脉象虚浮的，适宜发汗，发汗适宜用桂枝汤。这难道说明桂枝是止汗的吗？
只是麻黄汤中没有芍药，而用了麻黄；桂枝汤中没有麻黄，而用了芍药。大概是因为桂枝性味发散，芍药性味收敛。用芍药配合桂枝，则桂枝的药力就不猛烈；用桂枝配合芍药，则芍药的寒性就不明显。但是凭借芍药的柔弱，终究不能胜过桂枝的勇猛，而且芍药能滋养调和营气（行于脉中的精气），恰好足以帮助桂枝发出汗来，所以桂枝汤也是发散剂，只是麻黄汤药力峻猛，而桂枝汤药力缓和罢了。
因此，凡是寒邪深重固结的，恐怕服用桂枝汤不能解除表邪，反而助长热邪，所以脉紧无汗的，适宜用麻黄而不适宜用桂枝；如果脉浮缓有汗，或者脉浮弱的，因为风邪尚浅，适宜用桂枝而不适宜用麻黄。所以麻黄汤是发表（解除表邪）的第一选择，而桂枝汤则是解表的次选。
现在的医生不能明察这一点，只听到“汗不出者，不可与桂枝”，就认为桂枝能止汗，错误也太大了，却不知道止汗在于芍药，不在于桂枝。只是桂枝性温，能增强卫气（护卫肌表的气）。如《内经》所说：阴气有余，会导致多汗且身体寒冷。张仲景说：极寒反而出汗的，这是亡阳（阳气衰竭）导致的汗出，扶助阳气才可以止汗，那么正适宜使用桂枝了。
另外，《伤寒论》以太阳病无汗、脉紧为伤寒，汗出、脉缓为中风，这是风寒的区别。但是大青龙汤的证治中说：太阳中风，脉象浮紧，发热恶寒，身体疼痛，无汗且烦躁的，用大青龙汤主治。这难道不是太阳中风也有脉紧无汗的情况吗？可见风和寒，本来相距不远，只是风邪浅而寒邪深罢了，浅属于阳而深属于阴罢了。
况且近来见到外感寒邪的人，大多都是伤寒发热、脉紧、无汗等证候，至于中风这一证，说是脉缓有汗，又复发热，这种病其实并不常见，即使有，也必定是外因少，而内因多。如果学者对“风寒”二字，以及麻黄汤和桂枝汤这两方，一定要区分它们的阴阳同异，并固执地以此争辩，那就差得太远了。本卷前面有风寒辨，应该一并考察。
Note: The *Treatise on Cold Pathogenic Diseases* (*Shanghan Lun*) states: In Taiyang disease (a syndrome caused by pathogenic factors affecting the Taiyang meridian), characterized by headache, fever, aversion to cold, body pain, vomiting and qi rebellion, with pulse tightness in all three positions (cun, guan, chi), absence of sweating, and wheezing, it is named Cold Damage (*Shanghan*), and Ma Huang Tang (Ephedra Decoction) is the primary treatment. It also states: In Taiyang disease, characterized by headache, fever, sweating, aversion to wind, and a slow pulse, it is named Wind Strike (*Zhongfeng*), and Gui Zhi Tang (Cinnamon Twig Decoction) is the primary treatment. This distinguishes Cold Damage by the absence of sweating and tight pulse, thus requiring Ma Huang Tang; and Wind Strike by the presence of sweating and slow pulse, thus requiring Gui Zhi Tang. This is the distinction between them.
Furthermore, the *Treatise* states: Gui Zhi Tang is originally intended to resolve the muscle layer; if the patient has a floating-tight pulse, fever, but no sweating, it must not be administered. One must always keep this in mind to avoid error. However, why does it also state: When the exterior syndrome of Taiyang disease has not resolved and the pulse is floating and weak, sweating should be induced, and Gui Zhi Tang is appropriate? And when Yangming disease (a syndrome caused by pathogenic factors affecting the Yangming meridian) presents with fever around the Shen hour (3-5 PM) and a deficient-floating pulse, sweating should be induced, and Gui Zhi Tang is appropriate for inducing sweat. Does this imply that Gui Zhi stops sweating?
The difference lies in the composition: Ma Huang Tang lacks Shao Yao (Paeoniae Radix Alba) but uses Ma Huang (Ephedrae Herba); Gui Zhi Tang lacks Ma Huang but uses Shao Yao. Generally, Gui Zhi has a dispersing nature, while Shao Yao has an astringent nature. When Shao Yao accompanies Gui Zhi, Gui Zhi’s action becomes less harsh; when Gui Zhi accompanies Shao Yao, Shao Yao’s cold nature is mitigated. However, Shao Yao’s mildness cannot ultimately overcome Gui Zhi’s vigor. Moreover, Shao Yao nourishes and harmonizes Ying Qi (nutritive qi circulating within the vessels), which sufficiently assists Gui Zhi in inducing sweating. Therefore, Gui Zhi Tang is also a dispersing formula, but whereas Ma Huang Tang is potent and harsh, Gui Zhi Tang is gentle and slow.
Thus, for deep-seated and stubborn cold pathogens, one fears that using Gui Zhi Tang will fail to release the exterior and instead exacerbate heat. Therefore, cases with a tight pulse and no sweating are suitable for Ma Huang Tang rather than Gui Zhi Tang. Conversely, cases with a floating-slow pulse and sweating, or a floating-weak pulse, indicate shallow wind pathogens, making Gui Zhi Tang suitable rather than Ma Huang Tang. Hence, Ma Huang Tang is the premier formula for releasing the exterior, while Gui Zhi Tang is secondary.
Contemporary physicians often fail to discern this nuance. Upon hearing "those without sweating should not receive Gui Zhi," they erroneously conclude that Gui Zhi stops sweating. This is a significant mistake. They do not realize that the sweating-stopping effect resides in Shao Yao, not Gui Zhi. Gui Zhi is warm in nature and strengthens Wei Qi (defensive qi). As stated in the *Neijing*: Excess Yin leads to profuse sweating and cold sensations. Zhang Zhongjing stated: Sweating occurring despite extreme cold indicates Yang Collapse (loss of Yang qi); tonifying Yang can stop sweating, in which case Gui Zhi is indeed appropriate.
Additionally, the *Treatise* distinguishes Cold Damage (no sweat, tight pulse) from Wind Strike (sweat, slow pulse) based on wind versus cold. However, the indications for Da Qing Long Tang (Major Blue Green Dragon Decoction) state: In Wind Strike, with a floating-tight pulse, fever, aversion to cold, body pain, no sweating, and irritability, Da Qing Long Tang is indicated. Does this not show that Wind Strike can also present with a tight pulse and no sweating? This demonstrates that wind and cold are fundamentally close; wind is shallow while cold is deep. Shallow conditions belong to Yang, while deep conditions belong to Yin.
Moreover, recently observed cases of external cold invasion predominantly present as Cold Damage with fever, tight pulse, and no sweating. Cases of Wind Strike, characterized by slow pulse, sweating, and recurrent fever, are rarely seen. If they do occur, they are likely due more to internal causes than external ones. If scholars insist on distinguishing the yin-yang similarities and differences between "wind/cold" and the formulas "Ma Huang Tang/Gui Zhi Tang" to use as rigid arguments, they would be far off the mark. Refer to the preceding section on the differentiation of wind and cold for further examination.