伤寒一证。古称大病。而太阳一经。其头绪之繁多。方法之庞杂。又甚于他经。是以辨之非易。然非不可辨
也。盖太阳之经。其原出之病。与正治之法。不过二十余条而已。其他则皆权变法、斡旋法、救逆法、类病法
也。假使治伤寒者。审其脉之或缓或急。辨其证之有汗无汗。则从而汗之解之。如桂枝、麻黄等法则邪却
而病解矣。其或合阳明。或合少阳。或兼三阳者。则从而解之清之。如葛根、黄芩、白虎等法。亦
邪分而病解矣。此为正治之法。顾人气体有虚实之殊。脏腑有阴阳之异。或素有痰饮痞气。以及咽燥淋疮汗衄之疾。
或适当房室金刃产后亡血之余。是虽同为伤寒之候。不得竟从麻桂之法矣。于是乎有小建中、炙甘草、
大小青龙及桂枝二麻黄一等汤也。是为权变之法。而用桂枝、麻黄等法。又不能必其无过与不及之弊。
或汗出不彻。而邪不外散。则有传变他经。及发黄蓄血之病。或汗出过多。而并伤阳气。则
有振振擗地。肉 筋惕等证。于是乎有可更发汗、更药发汗。及真武、四逆等法也。是为斡
旋之法。且也医学久芜。方法罕熟。或当汗而反下。或既下而复汗。以及温针、艾灼、水 。
种种混施。以致结胸痞满。挟热下利。或烦躁不得眠。或内烦饥不欲食。或惊狂不安。或肉上
粟起。于是乎有大小陷胸、诸泻心汤、文蛤散等方也。此为救逆之法。至于天之邪气。共有六淫。
太阳受邪。亦非一种。是以伤寒之外。又有风温、温病、风湿、中湿、湿温、中 、霍乱等证。
其形与伤寒相似。其治与伤寒不同。于是乎有桂附、术附、麻黄、白术、瓜蒂、人参、白虎
等方。此为伤寒类病法也。夫振裘者必挈其领。整纲者必提其纲。不知出此。而徒事区别。纵极
清楚。亦何适于用哉。兹略引大端于前。分列纲目于后。而仲景之方与法。罔不备举。然后太
阳一经。千头万绪。总归一贯。比于百八轮珠。个个在手矣。六经仿此。详见各篇。
The syndrome of Shanghan (Cold Damage) was called a major disease in ancient times. Among the meridians, the Taiyang (Greater Yang) meridian is characterized by its numerous complexities and complicated treatment methods, surpassing other meridians. Therefore, distinguishing it is not easy. However, it is not indistinguishable.
Generally speaking, the primary pathological manifestations and standard treatment principles of the Taiyang meridian amount to no more than twenty-plus clauses. The rest are all adaptive methods (Quan Bian Fa), mediating methods (Wo Xuan Fa), rescue methods for adverse reactions (Jiu Ni Fa), and differential diagnosis methods for similar diseases (Lei Bing Fa).
If a practitioner treating Shanghan examines whether the pulse is slow or rapid, and distinguishes whether there is sweating or not, they can then apply diaphoretic and resolving methods. By using formulas such as Guizhi Tang (Cinnamon Twig Decoction) and Mahuang Tang (Ephedra Decoction), the pathogenic factor is expelled and the disease resolves.
In cases where the disease combines with the Yangming (Yang Brightness) meridian, or the Shaoyang (Lesser Yang) meridian, or involves all three Yang meridians simultaneously, one should employ methods to resolve the exterior and clear internal heat. Formulas like Gegen Tang (Puerariae Decoction), Huangqin Tang (Scutellariae Decoction), and Baihu Tang (White Tiger Decoction) also lead to the dispersion of pathogens and resolution of the disease. These constitute the standard treatment methods (Zheng Zhi Zhi Fa).
However, human constitutions vary in deficiency and excess, and zang-fu organs differ in yin and yang. Some patients may have pre-existing conditions such as phlegm-fluid retention, epigastric fullness (Pi Qi), dry throat, stranguria, sores, spontaneous sweating, or epistaxis. Others may be in a debilitated state due to sexual exhaustion, trauma from metal or blades, or postpartum blood loss. Although these present as Shanghan syndromes, one cannot simply adhere to the methods of Mahuang Tang or Guizhi Tang. Thus, formulas such as Xiaojianzhong Tang (Minor Construct the Middle Decoction), Zhigancao Tang (Honey-Processed Licorice Decoction), Daqinglong Tang (Major Green Dragon Decoction), Xiaoqinglong Tang (Minor Green Dragon Decoction), and Guizhi Er Mahuang Yi Tang (Guizhi-Two-Mahuang-One Decoction) are employed. This represents the adaptive method (Quan Bian Zhi Fa).
Nevertheless, when using Guizhi Tang or Mahuang Tang, one cannot guarantee the absence of errors due to excess or insufficiency. If sweating is incomplete and the pathogen does not disperse outward, the disease may transmit to other meridians, leading to jaundice or blood stasis accumulation. If sweating is excessive, damaging the yang qi, symptoms such as tremors, falling prone, muscle twitching, and tendon spasms may occur. Consequently, methods to induce further sweating or use specific medicinals for sweating, along with Zhenwu Tang (True Warrior Decoction) and Sini Tang (Four Reversal Decoction), are utilized. This is the mediating method (Wo Xuan Zhi Fa).
Moreover, medical practice has long been neglected, and treatment methods are rarely mastered. Practitioners might mistakenly use purgatives instead of diaphoretics when appropriate, or apply diaphoretics after purgation. They might also indiscriminately combine warm needle therapy, moxibustion, and water therapies. This leads to complications such as chest binding (Jie Xiong), epigastric fullness, diarrhea with heat, irritability and insomnia, inner irritability with hunger but lack of appetite, fright and mania, or cutaneous gooseflesh. In response, formulas like Daxiexiong Tang (Major Xiexia Decoction), Xiaoxiexiong Tang (Minor Xiexia Decoction), various Xiexin Tangs (Xiexin Decoctions), and Wen Ge San (Clam Shell Powder) are prescribed. This constitutes the rescue method for adverse reactions (Jiu Ni Zhi Fa).
Regarding pathogenic factors from heaven, there are six types of exogenous evils (Six Yin: Wind, Cold, Summerheat, Dampness, Dryness, Fire). The Taiyang meridian is susceptible to more than just cold. Besides Shanghan, there are syndromes such as Fengwen (Wind-Warmth), Wenbing (Warm Disease), Fengshi (Wind-Dampness), Zhongshi (Dampness Strike), Shiwen (Damp-Warmth), Zhongshu (Heat Stroke), and Huoluan (Cholera-like disorder). Their clinical presentations resemble Shanghan, but their treatments differ. Thus, formulas containing Guizhi and Fuzi, Shu Fu Tang (Atractylodes and Aconite Decoction), Mahuang Baizhu Tang (Ephedra and Atractylodes Decoction), Gouti San (Melon Seed Powder), Renshen Tang (Ginseng Decoction), and Baihu Tang (White Tiger Decoction) are used. This is the method for differentiating similar diseases (Shanghan Lei Bing Fa).
To shake a fur coat, one must grasp the collar; to organize a net, one must lift the main rope. Without grasping this key principle, merely engaging in trivial distinctions, even if extremely clear, would be of little practical use. Here, the main outlines are briefly presented first, followed by detailed categorization. The formulas and methods of Zhang Zhongjing are comprehensively listed. Thus, the myriad complexities of the Taiyang meridian are unified into a coherent system, akin to holding every bead of a hundred-and-eight-bead rosary in hand. The same logic applies to the Six Meridians, as detailed in subsequent chapters.