本草有曰。轻可去实。即麻黄葛根之属是也。实为寒邪在表。皮腠坚实。荣卫胜。津
液内固之表实。非腹满便难之内实也。圣济经曰。汗不出而腠密。邪气胜而中蕴。
轻剂所以扬之。即麻黄葛根之轻剂耳。麻黄味甘苦。用以为君者。以麻黄为轻剂。
而专主发散。是以为君也。桂枝为臣者。以风邪在表又缓。而肤理疏者。则必以桂
枝解其肌。是用桂枝为臣。寒邪在经。表实而腠密者。则非桂枝所能独散。必专麻
黄以发汗。是当麻黄为主。故麻黄为君。而桂枝所以为臣也。内经曰。寒淫于内。治
以甘热。佐以辛苦者。是兹类欤。甘草味甘平。杏仁味甘苦温。用以为佐使者。内经
曰。肝苦急。急食甘以缓之。肝者荣之主也。伤寒荣胜卫固。血脉不利。是专味甘之
物以缓之。故以甘草杏仁为之佐使。且桂枝汤主中风。风则伤卫。风邪并于卫。则
卫实而荣弱。仲景所谓汗出恶风者。此为荣弱卫强者是矣。故桂枝汤佐以芍药。
用和荣也。麻黄汤主伤寒。寒则伤荣。寒邪并于荣。则荣实而卫虚。内经所谓气之
所并为血虚。血之所并为气虚者是矣。故麻黄佐以杏仁。用利气也。若是之论。实
处方之妙理。制剂之渊微。该通君子。熟明察之。乃见功焉。
麻黄（君三两去节） 桂枝（臣二两去皮） 甘草（佐使二两炙） 杏仁（佐使七十枚去皮尖）
上四味。以水九升。先煮麻黄。减二升。去上沫。内诸药。煮取二升半。去渣。温服八
合。缓取微汗。并不须啜粥。余如桂枝法将息。
The Materia Medica states: "Light and dispersing agents can eliminate exterior excess," referring to herbs such as Ephedrae Herba (Mahuang, 麻黄) and Puerariae Radix (Gegen, 葛根). The term "excess" here refers to an exterior excess condition caused by cold pathogenic factors invading the exterior, resulting in solid and dense skin and interstices, with vigorous Ying (Nutritive) and Wei (Defensive) qi, and internal retention of body fluids. This is distinct from interior excess characterized by abdominal fullness and difficult defecation. The *Shengji Jing* (Holy Relief Classic) states: "When sweat does not occur and the interstices are dense, and pathogenic factors are vigorous and internally constrained, light and ascending agents are used to disperse them." This refers precisely to the light agents like Mahuang and Gegen.
Ephedrae Herba (Mahuang, 麻黄) has a sweet and bitter taste. It is employed as the Sovereign herb because it belongs to the category of light agents and specializes in dispersing and releasing the exterior; hence, it serves as the Sovereign. Cinnamon Twig (Guizhi, 桂枝) serves as the Minister herb. When wind pathogenic factors are on the exterior and the condition is relatively mild, or when the muscle texture is loose, one must use Guizhi to resolve the muscle layer; thus, it is designated as the Minister. However, when cold pathogenic factors invade the meridians, presenting with exterior excess and dense interstices, Guizhi alone cannot disperse the pathogen. One must rely specifically on Mahuang to induce sweating. In such cases, Mahuang takes precedence. Therefore, Mahuang is the Sovereign, and Guizhi is the Minister. The *Neijing* (Inner Canon) states: "When cold invades excessively within, treat it with sweet and hot substances, assisted by acrid and bitter ones." This likely applies to this scenario.
Licorice Root (Gancao, 甘草) has a sweet and neutral taste, and Apricot Seed (Xingren, 杏仁) has a sweet, bitter, and warm taste. They are used as Assistant and Envoy herbs. The *Neijing* states: "When the Liver suffers from tension/spasm, eat sweet foods to relax it." The Liver is the master of Ying blood. In Shaoyin disease (referring to Cold Damage affecting Ying), if Ying qi is vigorous and Wei qi is fixed, leading to poor circulation of blood vessels, one should exclusively use sweet-tasting substances to relax the tension. Therefore, Gancao and Xingren are used as Assistants and Envoys.
Furthermore, Guizhi Tang (Cinnamon Twig Decoction) treats Wind Strike syndrome. Wind pathogenic factors tend to injure Wei qi. When wind pathogenic factors merge with Wei, Wei becomes excessive while Ying becomes deficient. Zhang Zhongjing's description of "sweating and aversion to wind" refers to this state of deficient Ying and excessive Wei. Hence, in Guizhi Tang, Paeonia Root (Shaoyao, 芍药) is added as an assistant to harmonize Ying qi. Mahuang Tang (Ephedra Decoction) treats Cold Damage syndrome. Cold pathogenic factors tend to injure Ying qi. When cold pathogenic factors merge with Ying, Ying becomes excessive while Wei becomes deficient. This corresponds to the *Neijing*'s statement: "Where Qi merges, Blood becomes deficient; where Blood merges, Qi becomes deficient." Therefore, in Mahuang Tang, Xingren is added as an assistant to promote the movement of Qi. Such discussions reveal the profound principles of prescription formulation and the subtle nuances of decoction preparation. Only those who are thorough and discerning can fully understand and achieve therapeutic success upon careful examination.
Ephedrae Herba (Mahuang, 麻黄) [Sovereign, 3 liang, nodes removed]
Cinnamon Twig (Guizhi, 桂枝) [Minister, 2 liang, bark removed]
Prepared Licorice Root (Zhi Gancao, 炙甘草) [Assistant/Envoy, 2 liang, honey-fried]
Apricot Seed (Xingren, 杏仁) [Assistant/Envoy, 70 seeds, skin and tips removed]
Take the above four ingredients. Add nine sheng of water. First, boil Mahuang until the volume reduces by two sheng. Remove the foam that rises to the surface. Then add the remaining herbs. Boil until two and a half sheng of liquid remains. Strain out the dregs. Take eight he of the decoction warm. Aim for a slight perspiration. There is no need to drink porridge to assist sweating. Rest and care instructions follow those of Guizhi Tang.