发汗。或云当得汗解。或云当发汗更发汗。并发汗。宜桂枝汤者数方。是用桂枝发汗也
。复
云。无汗不得服桂枝。又曰汗家不得重发汗。又曰发汗过多者。却用桂枝甘草汤。是闭汗也
。一药二用。如何说得。仲景发汗与本草之义相通为一。答曰。本草云。桂味辛甘热无毒。
能为百药长通血脉止烦出汗者。是调血而汗自出也。仲景云。脏无他病。发热自汗者。此卫
气不和也。又云。自汗者为荣气和。荣气和则外不谐。卫气不与荣气相和谐也。荣气和则愈
。故皆用桂枝汤调和荣卫。荣卫既和。则汗。自出矣。风邪由此而解非桂枝能开腠理发出汗
也。以其固闭荣血。卫气自和。邪无容地而出矣。其实则闭汗孔也。昧者不解闭汗之意。凡见病
者。便用桂枝汤发汗。若与中风自汗者合其效桴鼓。因见其取效而病愈。则曰。此桂枝发出
汗也。遂不问伤寒无汗者。亦与桂枝汤误之甚矣。故仲景言无汗不得服桂枝。是闭汗孔也。
又云。发汗多义（手冒）心。心悸欲得按者。用桂枝甘草汤。是亦闭汗孔也。又曰汗家不得
重
发汗。若桂枝汤发汗。是重发汗也。凡桂枝条下言发字。当认作出字。是汗自然出也。非若
麻黄能开腠理而发出汗也。本草出汗二字。上文有通血脉一句。是非三焦卫气皮毛中药。是
为荣血中药也。如是则出汗二字。当认作荣卫和自然汗出。非桂开腠理而发出汗也。故后人
用
桂治虚汗。读者当逆察其意则可矣。噫神农之作于其前。仲景之述于其后。前圣后圣其揆一
也。
Diaphoresis. Some say that resolution should be achieved through sweating. Others say that one should induce sweating, and then induce sweating again. All formulas employing Guizhi Tang (Cinnamon Twig Decoction) utilize Guizhi (Cinnamon Twig) to induce diaphoresis.
It is further stated that Guizhi (Cinnamon Twig) must not be administered when there is no sweat. It is also stated that individuals who are prone to sweating must not undergo repeated forced diaphoresis. Furthermore, for those who have suffered from excessive sweating, Guizhi Gancao Tang (Cinnamon Twig and Licorice Decoction) is used. This serves to close the pores and stop sweating.
How can a single herb have two opposing functions? Zhang Zhongjing’s understanding of diaphoresis is consistent with the principles of Materia Medica.
The answer is: The Materia Medica states that Guizhi (Cinnamon Twig) has an acrid, sweet, and hot nature, and is non-toxic. It acts as the leader among herbs, unblocking the blood vessels, relieving irritability, and inducing sweat. This mechanism works by harmonizing the blood, causing sweat to emerge naturally.
Zhang Zhongjing states: When the internal organs are free from other pathologies, but fever and spontaneous sweating occur, this indicates disharmony of Wei Qi (Defensive Qi).
He also states: Spontaneous sweating occurs because Ying Qi (Nutritive Qi) is harmonious, yet the exterior remains discordant; specifically, Wei Qi (Defensive Qi) does not harmonize with Ying Qi (Nutritive Qi). If Ying Qi (Nutritive Qi) becomes harmonious, recovery ensues.
Therefore, Guizhi Tang (Cinnamon Twig Decoction) is used to harmonize Ying Qi (Nutritive Qi) and Wei Qi (Defensive Qi). Once Ying Qi (Nutritive Qi) and Wei Qi (Defensive Qi) are harmonized, sweat will emerge naturally. The Wind Pathogen is thereby resolved; it is not that Guizhi (Cinnamon Twig) opens the Cou Li (skin and hair follicles) to force out sweat.
Rather, it consolidates Ying Blood (Nutritive Blood), allowing Wei Qi (Defensive Qi) to become harmonious, leaving no room for pathogens, which are thus expelled. Its actual function is to close the sweat pores.
Ignorant practitioners fail to understand the meaning of "closing the sweat pores." Upon seeing any patient, they indiscriminately administer Guizhi Tang (Cinnamon Twig Decoction) to induce diaphoresis. If this coincides with patients suffering from Wind Strike with spontaneous sweating, the therapeutic effect is immediate and effective, like a drumstick striking a drum.
Seeing its efficacy and the subsequent cure, they conclude: "This sweat was induced by Guizhi (Cinnamon Twig)." Consequently, they fail to distinguish between Cold Damage cases without sweat and administer Guizhi Tang (Cinnamon Twig Decoction) erroneously, which is a grave mistake.
Thus, Zhang Zhongjing states that Guizhi (Cinnamon Twig) must not be taken when there is no sweat, precisely because it closes the sweat pores.
He also states: When excessive sweating leads to palpitations in the heart region, and the patient desires pressure on the chest to alleviate discomfort, Guizhi Gancao Tang (Cinnamon Twig and Licorice Decoction) is used. This too serves to close the sweat pores.
Furthermore, it is stated that individuals prone to sweating must not undergo repeated forced diaphoresis. Using Guizhi Tang (Cinnamon Twig Decoction) to induce sweating in such cases constitutes repeated forced diaphoresis.
Wherever the character "fa" (to emit/release) appears under the entry for Guizhi (Cinnamon Twig), it should be understood as "chu" (to come out), meaning sweat emerges naturally. It does not open the Cou Li (skin and hair follicles) to force out sweat, unlike Mahuang (Ephedra Herb).
In the Materia Medica, the phrase "induces sweat" is preceded by "unblocks the blood vessels." This indicates that it is not an herb acting on the San Jiao (Triple Burner), Wei Qi (Defensive Qi), or the skin and hair follicles, but rather an herb acting on Ying Blood (Nutritive Blood).
If this is the case, then the term "induces sweat" should be interpreted as sweat emerging naturally due to the harmony of Ying Qi (Nutritive Qi) and Wei Qi (Defensive Qi), not as Guizhi (Cinnamon Twig) opening the Cou Li (skin and hair follicles) to force out sweat.
Therefore, when later practitioners use Guizhi (Cinnamon Twig) to treat deficiency-type sweating, readers should interpret its intent inversely.
Alas! Shennong authored his work beforehand, and Zhang Zhongjing expounded upon it afterwards. The principles of the sages of old and the sages of later times are identical.