寒邪伤人阳气，郁而成热，皮肤闭而成实，麻黄轻以去实，辛以发阳气，温以散寒气。
杏仁佐麻黄通肺气，使腠理开泄，王好古谓其为治卫实之药者是也。然泄而不收、升而不降，桂
枝、甘草虽以佐之，实监制之耳！东垣云∶麻黄汤是阳经卫药也，开腠理使阳气申泄，此药
为卫实也。
大青龙治风寒外壅，而闭热于经者；小青龙治风寒外壅，而伏饮于内者。夫热郁于经，
而不
用石膏，汗为热隔，宁有能发之者乎？饮伏于内，而不用姜、夏，邪与饮抟，宁有能散之者
乎？其芍药、五味，不特靖逆气而安肺气，抑且制麻、桂、姜、辛之势，使不相 而相就，
以成内外协济之功也。
伤寒脉浮，医以火迫劫之亡阳，必惊狂、起卧不安者，桂枝去芍药加蜀漆龙骨牡蛎救逆
汤主
之。按此所谓阳者，乃心之阳，盖即神也。火气通于心，神被迫而不收，与发汗亡阳者不同
。发汗者，动其肾，则厥逆、筋惕肉 ，故当用四逆；被火者，伤其心，则惊狂、起卧不安
，故当用龙、牡。其去芍药，加蜀漆者，盖欲甘辛急复心阳，而不须酸味更益营气也。与发
汗后，其人叉手自冒心、心下悸欲得按者，用桂枝甘草汤同。蜀漆即常山苗，味辛，能去胸
中邪结气。此症火气内逼心包，故须以逐邪而安正耳！
Cold pathogenic factors invade the human body, damaging Yang Qi (Yang energy), causing it to stagnate and transform into heat. The skin and pores become closed, leading to an excess syndrome. Ephedrae Herba (Mahuang, 麻黄) is light in nature to dispel excess; its pungent flavor disperses Yang Qi; its warm property scatters cold pathogens.
Prunus Armeniaca Seed (Xingren, 杏仁) assists Ephedrae Herba in unblocking Lung Qi, allowing the pores to open and release. Wang Haogu described it as a medicine for treating excess in the Wei (Defensive) level, which is accurate. However, if there is only dispersion without retention, and only ascending without descending, although Cinnamon Twig (Guizhi, 桂枝) and Licorice Root (Gancao, 甘草) serve as assistants, they essentially act as regulators and controllers! Li Dongyuan stated: Mahuang Tang (Ephedra Decoction) is a Wei-level medicine for the Yang meridians; it opens the pores to allow Yang Qi to be ventilated and released, addressing excess in the Wei level.
Da Qing Long Tang (Major Blue-Green Dragon Decoction) treats exterior constraint by wind-cold with heat trapped within the meridians; Xiao Qing Long Tang (Minor Blue-Green Dragon Decoction) treats exterior constraint by wind-cold with retained fluid-phlegm inside. If heat is stagnant in the meridians but Gypsum (Shigao, 石膏) is not used, how can sweat be released when it is blocked by heat? If fluid-phlegm is retained internally but Dried Ginger (Ganjiang, 干姜) and Pinellia Tuber (Banxia, 半夏) are not used, how can the pathogen and fluid-phlegm be dispersed when they knot together? Schisandra Fruit (Wuweizi, 五味子) and Peony Root (Shaoyao, 芍药) not only calm rebellious Qi and stabilize Lung Qi, but also restrain the vigorous effects of Ephedrae Herba, Cinnamon Twig, Dried Ginger, and Asarum Root (Xixin, 细辛), preventing conflict and promoting synergy, thereby achieving cooperative effects inside and outside.
In Shanghan (Cold Damage) with a floating pulse, if a physician uses fire therapy to force sweating, resulting in the loss of Yang, symptoms such as fright, mania, restlessness, and inability to lie still will inevitably occur. This should be treated with Guizhi Qu Shaoyao Jia Shuqi Longgu Muli Jiuniu Tang (Cinnamon Twig Decoction without Peony plus Dichroa Root, Dragon Bone, and Oyster Shell to Rescue from Deviation). Note: The "Yang" mentioned here refers to Heart Yang, which is essentially Shen (Spirit/Mind). Fire pathogenic factors communicate with the Heart; when Shen is forced by fire and cannot consolidate, it differs from Yang loss due to excessive sweating. Excessive sweating disturbs Kidney Yang, leading to cold extremities and muscle twitching, thus requiring Sini Tang (Frigid Extremities Decoction). Injury by fire damages Heart Yang, leading to fright, mania, and restlessness, thus requiring Dragon Bone (Longgu, 龙骨) and Oyster Shell (Muli, 牡蛎). Removing Peony and adding Dichroa Root aims to use sweet and pungent flavors to rapidly restore Heart Yang, avoiding sour flavors that would further nourish Ying (Nutritive) Qi. This parallels the case after sweating where the patient crosses their hands over the heart, experiences palpitations under the epigastrium, and desires pressure, treated with Guizhi Gancao Tang (Cinnamon Twig and Licorice Decoction). Shuqi is the young shoot of Dichroa Febrifuga Radix (Changshan, 常山); it is pungent and can remove pathological qi accumulation in the chest. In this condition, fire forces inwardly into the Pericardium, so one must use herbs that expel pathogens to stabilize healthy Qi.