仲景桂枝汤加减法。凡十有九证。但云芍药。圣惠方皆用赤芍药。孙尚方皆用白芍药。圣惠乃太宗朝命
王怀德等编集。孙兆为累朝医师。不应如此背戾，然赤白补泻。极有利害。常见仲景桂枝第四十七证云。
病发热。汗出。此为荣弱卫强。故使汗出。欲救邪风。宜桂枝汤。盖风伤卫而邪乘之。则卫强。荣虽不受邪终
非适平也。故卫强则荣弱。仲景以桂枝发其邪。以芍药助其弱。故知用白芍药也。荣既弱而不受病。乃以
赤芍药泻之。决非仲景意。至于小建中。为尺迟血弱而设也。举此皆用白芍药。而仲景亦止称芍药。可以
类推矣。
仲景论中。百一十三方。为圆者有五。理中、陷胸、抵当、麻仁、乌梅是已。理中、陷胸、抵当。
皆大弹圆。煮化而服之。与汤无异。至于麻仁治脾约证。乌梅治湿 证。皆欲必达下部。故用小圆。
其它皆欲入经络。逐邪毒。破坚癖。导瘀血燥屎之类。须凭汤剂以涤除也。余见俗医用小圆药巴豆
以下邪毒。而杀人者。不可胜数。盖巴豆止导食积。而不能去热毒。既下之后。藏气虚。而邪毒宛
然犹在。更再以大黄朴硝下之。鲜不致毙。大抵下药。欲其必中。必当一服而止也。故不可不慎欤。
仲景论表证。一则桂枝。二则麻黄。三则青龙。桂枝治中风。麻黄治伤寒。青龙治中风见寒脉。
伤寒见风脉。此三者人皆能言之。而不知用药对病之妙处。故今之医者不敢用仲景方。无足怪也。
且脉浮而缓者。中风也。故啬啬恶寒。淅淅恶风。翕翕发热。仲景以桂枝对之。脉浮紧而涩者。
伤寒也。故头痛发热。身疼腰痛。骨节疼痛。恶风。无汗而喘。仲景以麻黄对之。至于中风脉浮
紧。伤寒脉浮缓。仲景皆以青龙对之。何也。予尝深究三者。审于证候。脉息相对。用之无不应手而愈。
何以言之。风伤卫。卫、气也。寒伤荣。荣、血也。荣行脉中。卫行脉外。风伤卫。则风邪干阳气。
阳气不固。发越而为汗。是以自汗而表虚。故仲景用桂枝以发其邪。用芍药以助其血。盖中风则病在
脉之外。其病稍轻。虽同曰发汗。特解肌之药耳。故桂枝证云。令遍身 微似有汗者益佳。不可令
如水流离。病必不除。是知中风不可大发其汗。大发其汗。则反动荣血。邪乘
虚而居其中。故不除也。寒伤荣。则寒邪干阴血。而荣行脉中者也。寒邪居脉中。则非特荣受病也。邪自内
作。则并与卫气犯之。久则浸淫及骨。是以汗不出而烦冤。仲景以麻黄大发其汗。又以桂枝辛甘。而其发
散。欲捐其内外之邪。荣卫之病故尔。大抵二药皆发汗。而桂枝则发其卫之邪。麻黄并与荣卫而治之。固
有浅深也。何以验之。仲景桂枝第十九证云。病尝自汗出者。以为荣气和。荣气和者。外不谐。以卫气不共
荣气谐和故耳。荣行脉中。卫行脉外。复发其汗。荣卫和则愈。宜桂枝汤。又第四十七证云。发热汗出者。此
为荣弱卫强。故使汗出。欲救邪风。宜桂枝汤。是知中风汗出者。荣和而卫不和也。又第一卷云。寸口脉浮
而紧。浮则为风。紧则为寒。风则伤卫。寒则伤荣。荣卫俱病。骨节烦疼。当发其汗。是知伤寒浮紧者。荣卫俱
病也。麻黄汤中。并桂枝而用。此仲景之意欤。至于青龙。虽治伤寒见风脉。伤风见寒脉。然仲景云。汗出恶
风者。服之则筋惕肉 。故青龙一证尤难用。必须形证谛当。然后可行。王实止以桂枝麻黄各半汤代之。
盖慎之者也。
The modification methods of Guizhi Tang (Cinnamon Twig Decoction) in Zhang Zhongjing's *Shanghan Lun* (Treatise on Cold Pathogenic Diseases) cover nineteen syndromes. The text merely states "Shaoyao" (Paeonia Root), whereas the *Taiping Shenghui Fang* (Holy惠民 Formulas of the Taiping Era) uses all Chishao Yao (Red Paeonia Root), and Sun Zhao's formularies use all Baishao Yao (White Paeonia Root). The *Taiping Shenghui Fang* was compiled under the order of Emperor Taizong of Song by Wang Huaide and others, while Sun Zhao served as a physician to successive dynasties; it is unlikely that he would act so contrary to reason. However, there are significant differences in benefit and harm between the purgative effects of Red Paeonia and the tonifying effects of White Paeonia.
I often see the forty-seventh syndrome of Guizhi Tang in Zhang Zhongjing stating: "The patient has fever and sweating; this is due to Ying deficiency and Wei excess, causing sweating. To rescue from pathogenic wind, Guizhi Tang is appropriate." Generally, wind damages Wei Qi, and pathogens take advantage to invade, leading to Wei excess. Although Ying does not directly receive the pathogen, it is ultimately not in a balanced state. Thus, Wei excess leads to relative Ying deficiency. Zhang Zhongjing uses Guizhi to disperse the pathogen and Shaoyao to assist the deficient Ying; therefore, it can be known that Baishao Yao (White Paeonia Root) should be used. Since Ying is already deficient and unable to bear disease, using Chishao Yao (Red Paeonia Root) to purge it is certainly not Zhang Zhongjing's intention. As for Xiaojianzhong Tang (Minor Construct the Middle Decoction), it is established for cases of slow chi pulse and blood deficiency. In all these examples, Baishao Yao is used, and Zhang Zhongjing only refers to it as "Shaoyao"; this can be inferred analogously.
Among the one hundred and thirteen formulas in Zhang Zhongjing's treatise, five are prepared as pills: Lizhong Wan (Regulate the Middle Pill), Xiongxiong Wan (Chest-Penetrating Pill), Didang Wan (Eliminate Stasis Pill), Maren Wan (Hemp Seed Pill), and Wumei Wan (Mume Pill). Lizhong, Xiongxiong, and Didang pills are large, like bullet seeds, boiled until dissolved before administration, which is no different from decoctions. Maren Wan treats Pi Yue Syndrome (Spleen Confinement Syndrome), and Wumei Wan treats conditions requiring the medicine to reach the lower parts, hence small pills are used. Other formulas aim to enter the meridians, expel toxic pathogens, break up hard accumulations and masses, and guide out stasis and dry feces; these must rely on decoctions to cleanse and remove them.
I have seen folk doctors using small pills containing Euphorbiae Lathyridis Fructus (Baidu Dou, Croton Seed) to purge toxic pathogens, resulting in countless deaths. Generally, Baidu Dou only guides food stagnation but cannot eliminate heat toxins. After purging, the Zang-Fu Qi becomes deficient, yet the toxic pathogens remain. If followed by Dahuang (Rhubarb Rhizome) and Xiaomiao (Mirabilite) to purge further, death is rarely avoided. Generally, when using purgatives, one aims for precise effect, stopping after a single dose. Therefore, caution is essential.
Zhang Zhongjing discusses exterior syndromes with three main approaches: first, Guizhi Tang; second, Mahuang Tang (Ephedra Decoction); third, Qinglong Tang (Azure Dragon Decoction). Guizhi Tang treats Fengzhong (Wind Strike/Attack), Mahuang Tang treats Shanghan (Cold Damage), and Qinglong Tang treats Fengzhong presenting with Han Mai (Cold Pulse) or Shanghan presenting with Feng Mai (Wind Pulse). While everyone can recite this, few understand the subtlety of matching medication to syndrome; thus, it is no surprise that contemporary physicians dare not use Zhang Zhongjing's formulas.
For instance, a floating and moderate pulse indicates Fengzhong. Symptoms include aversion to cold, aversion to wind, and mild fever. Zhang Zhongjing prescribes Guizhi Tang. A floating, tight, and choppy pulse indicates Shanghan. Symptoms include headache, fever, body ache, lower back pain, joint pain, aversion to wind, anhidrosis, and wheezing. Zhang Zhongjing prescribes Mahuang Tang. When Fengzhong presents with a floating-tight pulse, or Shanghan presents with a floating-moderate pulse, Zhang Zhongjing prescribes Qinglong Tang. Why? I have deeply investigated these three, carefully examining syndromes and pulses relative to each other, and their application yields immediate cures.
Why is this? Wind damages Wei Qi, which is Yang Qi; Cold damages Ying Qi, which is Yin Blood. Ying circulates within the vessels, while Wei circulates outside. Wind damaging Wei means the wind pathogen interferes with Yang Qi. Yang Qi fails to consolidate, dispersing as sweat, leading to spontaneous sweating and exterior deficiency. Therefore, Zhang Zhongjing uses Guizhi to disperse the pathogen and Shaoyao to support the blood. Fengzhong implies the disease is outside the vessels, slightly milder. Although both involve sweating, Guizhi specifically releases the muscle layer. Hence, the Guizhi syndrome states: "It is best if the whole body has slight perspiration; do not let it flow like water, or the disease will not be resolved." This shows that Fengzhong should not induce heavy sweating. Heavy sweating disturbs Ying and Blood, allowing pathogens to occupy the void, so the disease remains unresolved.
Cold damaging Ying means the cold pathogen interferes with Yin Blood, which circulates within the vessels. Cold residing in the vessels affects not only Ying but also, as the pathogen arises from within, invades Wei Qi. Over time, it infiltrates the bones, causing anhidrosis and inner vexation/oppression. Zhang Zhongjing uses Mahuang to induce heavy sweating and combines it with the acrid-sweet properties of Guizhi to disperse, aiming to expel both interior and exterior pathogens because both Ying and Wei are diseased. Both drugs induce sweating, but Guizhi disperses Wei pathogens, while Mahuang treats both Ying and Wei, showing a difference in depth.
How to verify this? The nineteenth syndrome of Guizhi Tang states: "Patients who frequently sweat spontaneously are considered to have harmonious Ying Qi. If Ying is harmonious but external disharmony exists, it is because Wei Qi does not harmonize with Ying. Ying circulates inside, Wei outside. Re-inducing sweating restores harmony; Guizhi Tang is suitable." The forty-seventh syndrome states: "Fever and sweating indicate Ying weakness and Wei strength, causing sweating. To rescue from pathogenic wind, Guizhi Tang is suitable." Thus, sweating in Fengzhong indicates harmonious Ying but disharmonious Wei.
Volume One states: "Cunkou pulse floating and tight: floating indicates wind, tight indicates cold. Wind damages Wei, cold damages Ying. If both Ying and Wei are diseased, causing bone and joint pain, sweating should be induced." Thus, a floating-tight pulse in Shanghan indicates both Ying and Wei are diseased. Mahuang Tang includes Guizhi, reflecting Zhang Zhongjing's intent.
Regarding Qinglong Tang, although it treats Shanghan with wind-pulse or Fengzhong with cold-pulse, Zhang Zhongjing warns: "If the patient sweats and fears wind, administering this causes muscle twitching. Therefore, the Qinglong syndrome is particularly difficult to apply; it requires exact correspondence of form and syndrome before use." Wang Shi substitutes it with Guizhi Mahuang Ban Tang (Half-Guizhi Half-Mahuang Decoction), likely out of prudence.