书曰∶无汗宜桂枝汤者，是用桂枝以发汗也。复曰∶无汗不得服桂枝。又曰∶发汗
过多者，却用桂枝甘草汤，是用桂枝以闭汗也。其一药二用者何说？盖桂为百药长，善
通血脉，故用以止烦出汗者，非桂能开腠理而发出汗也，以其调荣血，则卫气自和，邪
无容地遂自汗出而解矣。汗多用桂枝者，亦非桂枝能闭腠理而止汗也，以其调和荣卫，
则邪从汗出，邪去而汗自止矣。昧者不解其止汗发汗之意。凡见病者，便用桂枝，殊不
知，如遇太阳伤风自汗者，及中风自汗者，固获奇效，倘系太阳伤寒无汗，而骨髓无寒
者，而亦用之，为害岂浅浅乎？故仲景曰∶无汗不得服桂枝；又曰∶桂枝下咽，阳盛则毙者此耳。
麻黄得桂枝，则能发汗，芍药得桂枝，则能止汗，黄 得白术则止虚汗，防风得羌
活则治诸风，苍术得羌活则止身痛。柴胡得黄芩治热，附子得干姜治寒，羌活得川芎则
止头疼，川穹得天麻则止头眩，干葛得天花粉则止消渴，石膏得知母则止渴，香薷得扁
豆则消暑，黄芩得连翘则消毒，桑皮得苏子则止喘，杏仁得五昧则止嗽，丁香得柿蒂、
干姜则止呃，干姜得半夏则止呕，半夏得姜汁则回痰，贝母得栝蒌则开结痰，桔梗得升
麻开提血气，枳实得黄连则消心下痞，枳壳得桔梗能使胸中宽，知母、黄柏得山栀则降
火，豆豉得山栀则治懊 ，辰砂得酸枣则安神，白术得黄芩则安胎，陈皮得白术则补
脾，人参得五昧、麦冬则生肾水，苍术得香
附开郁结，浓朴得腹皮开膨胀，草果得山楂消肉积，神曲得麦芽能消食，乌梅得干葛则
消酒，砂仁得枳壳则宽中，木香得姜汁则散气，乌药得香附则顺气，芍药得甘草治腹痛
因虚，吴茱萸得良姜止腹痛因寒，乳香得没药大止诸痛，芥子得青皮治胁痛，黄 得大
附子则补阳，知母、黄柏得当归则补阴，当归得生地则生血，藕汁磨京墨则止血，红花
得当归则活血，归尾得桃仁则破血，大黄得芒硝则润下，皂荚得麝香则通窍，诃子得肉
果则止泻，木香得槟榔治后重，泽泻得猪芩则能利水，泽泻得白术则能收湿，此用药相
得之大端也。
The *Neijing* (Inner Canon) states: "For conditions without sweating, Guizhi Tang (Cinnamon Twig Decoction) is appropriate," which utilizes Guizhi (Cinnamon Twig) to induce sweating. It further states: "Guizhi should not be taken for conditions without sweating." It also says: "For patients who have sweated excessively, Guizhi Gancao Tang (Cinnamon Twig and Licorice Decoction) is used," which utilizes Guizhi to stop sweating. What is the rationale behind one herb having two different uses? Guizhi is regarded as the "chief of all herbs" and excels at unblocking blood vessels. Therefore, when used to relieve restlessness and induce sweating, it is not because Guizhi directly opens the *couli* (pores/skin interstices) to force sweat out, but because it harmonizes Ying Blood (nutritive blood circulating within the vessels), thereby allowing Wei Qi (defensive qi circulating outside the vessels) to become harmonious. With no place for pathogenic factors to reside, the body naturally sweats, leading to recovery. When Guizhi is used after excessive sweating, it is not because Guizhi directly closes the *couli* to stop sweating, but because it harmonizes Ying and Wei, allowing pathogens to exit with the sweat; once the pathogens are eliminated, sweating ceases naturally. Ignorant practitioners fail to understand this dual function of stopping and inducing sweating. They indiscriminately apply Guizhi to every patient. Unaware that while it yields miraculous results for Taiyang Wind Strike (Wind-Strike Syndrome of the Taiyang Channel) with spontaneous sweating, or Zhongfeng (Wind Stroke/Attack) with spontaneous sweating, its use in Taiyang Cold Damage (Cold-Damage Syndrome of the Taiyang Channel) without sweating—where there is no cold in the bone marrow—is extremely harmful. Thus, Zhang Zhongjing stated: "Do not take Guizhi for conditions without sweating"; and again, "If Guizhi Tang is ingested by a person with Yang Excess, death will ensue." This refers to such cases.
Mahuang (Ephedrae Herba) combined with Guizhi induces sweating; Shaoyao (Paeoniae Radix) combined with Guizhi stops sweating; Renshen (Ginseng Radix) combined with Baizhu (Atractylodis Macrocephalae Rhizoma) stops deficiency sweating; Fangfeng (Saposhnikoviae Radix) combined with Qianghuo (Notopterygii Rhizoma et Radix) treats various wind pathogens; Cangzhu (Atractylodis Rhizoma) combined with Qianghuo alleviates body pain. Chaihu (Bupleuri Radix) combined with Huangqin (Scutellariae Radix) treats heat syndromes; Fuzi (Aconiti Lateralis Radix Praeparata) combined with Ganjiang (Zingiberis Rhizoma) treats cold syndromes; Qianghuo combined with Chuanxiong (Ligustici Chuanxiong Rhizoma) relieves headache; Chuanxiong combined with Tianma (Gastrodiae Rhizoma) relieves dizziness; Gegen (Puerariae Lobatae Radix) combined with Tianhuafen (Trichosanthis Radix) relieves Xiao Ke (Wasting-Thirst); Shigao (Gypsum Fibrosum) combined with Zhimu (Anemarrhenae Rhizoma) relieves thirst; Xiangru (Elsholtziae Herba) combined with Bian Dou (Dolichoris Semen) dispels summerheat; Huangqin combined with Lianqiao (Forsythiae Fructus) clears toxicity; Sangbai Pi (Mori Cortex) combined with Suzi (Perillae Fructus) relieves wheezing; Xingren (Armeniacae Semen Amarum) combined with Wuweizi (Schisandrae Fructus) relieves cough; Dingxiang (Caryophylli Flos) combined with Shidi (Kaki Calyx) and Ganjiang relieves hiccups; Ganjiang combined with Banxia (Pinelliae Rhizoma) relieves vomiting; Banxia combined with Jiangzhi (Zingiberis Juice) resolves phlegm; Beimu (Fritillariae Bulbus) combined with Gualou (Trichosanthis Fructus) resolves congealed phlegm; Jiegeng (Platycodonis Radix) combined with Shengma (Cimicifugae Rhizoma) lifts Qi and Blood; Zhishi (Aurantii Fructus Immaturus) combined with Huanglian (Coptidis Rhizoma) eliminates epigastric fullness; Zhike (Aurantii Fructus) combined with Jiegeng broadens the chest; Zhimu and Huangbai (Phellodendri Cortex) combined with Zhizi (Gardeniae Fructus) descends fire; Douchi (Sojae Semen Preparatum) combined with Zhizi treats Ao Nu (restlessness and vexation); Chen Sha (Cinnabar) combined with Suanzaoren (Ziziphi Spinosae Semen) calms the spirit; Baizhu combined with Huangqin stabilizes pregnancy; Chenpi (Citri Reticulatae Pericarpium) combined with Baizhu tonifies the Spleen; Renshen combined with Wuweizi and Maidong (Ophiopogonis Radix) generates Kidney Water; Cangzhu combined with Xiangfu (Cyperi Rhizoma) opens depression; Houpo (Magnoliae Officinalis Cortex) combined with Fupi (Tangerine Peel/Atractylodis Fruit) reduces distension; Caoguo (Tsaoko Fructus) combined with Shanzha (Crataegi Fructus) resolves meat stagnation; Shenqu (Massa Medicata Fermentata) combined with Maiya (Hordei Fructus Germinatus) aids digestion; Wumei (Mume Fructus) combined with Gegen resolves alcohol intoxication; Sharen (Amomi Fructus) combined with Zhike regulates the Middle Jiao; Muxiang (Aucklandiae Radix) combined with Jiangzhi disperses Qi; Wuyao (Linderae Radix) combined with Xiangfu smooths Qi; Shaoyao combined with Gancao (Glycyrrhizae Radix et Rhizoma) treats abdominal pain due to deficiency; Wuzhuyu (Evodiae Fructus) combined with Liangjiang (Alpiniae Officinarum Rhizoma) treats abdominal pain due to cold; Ruxiang (Olibanum) combined with Moyao (Myrrha) greatly alleviates various pains; Jiezi (Sinapis Semen) combined with Qingpi (Citri Reticulatae Pericarpium Viride) treats hypochondriac pain; Huangqi (Astragali Radix) combined with Da Fuzi tonifies Yang; Zhimu and Huangbai combined with Danggui (Angelicae Sinensis Radix) tonifies Yin; Danggui combined with Shengdi (Rehmanniae Radix) generates Blood; Ou Zhi (Nelumbinis Rhizomatis Jus) mixed with Jing Mo (Ink Stick) stops bleeding; Honghua (Carthami Flos) combined with Danggui invigorates Blood; Guiwei (Angelicae Sinensis Radix Caudex) combined with Taoren (Persicae Semen) breaks up Blood stasis; Dahuang (Rhei Radix et Rhizoma) combined with Mangxiao (Natrii Sulfas) moistens and purges; Zaojiao (Gleditsiae Spina) combined with Shexiang (Moschus) opens orifices; Hezi (Terminaliae Fructus) combined with Rouguo (Myristicae Semen) stops diarrhea; Muxiang combined with Binglang (Arecae Semen) treats tenesmus; Zexie (Alismatis Rhizoma) combined with Zhuling (Polyporus) promotes urination; Zexie combined with Baizhu absorbs dampness. These are the major principles of synergistic herbal compatibility.