[General Rules]

There are many who have compiled books on Shanghan (Cold Damage). Those who only revere Zhang Zhongjing's *Shanghan Lun* while ignoring the supplementary treatments of later sages commit the error of excessive antiquarianism, as seen in books like *Leizheng Huoren Shu* (Classified Symptoms and the Living Person's Book); those who merely cater to popular convenience, mixing elegant and vulgar contents indistinguishably, thereby confusing readers about what truly belongs to Zhang Zhongjing, fall into the errors of mediocre practitioners, as seen in books like *Suoyan Yunsuo*. Only Mr. Lou Quanshan's *Gangmu* lists the primary diseases of the Six Channels at the forefront, followed by combined diseases, concurrent diseases, and various deteriorated conditions resulting from sweating, vomiting, or purging therapies; subsequently, it covers variations caused by seasonal pathogens, concluding with diseases specific to women and infants. Within each item, Zhang Zhongjing's methods are listed in detail, followed by supplementary methods from later sages. This approach encompasses the strengths of a hundred schools without confusion, and its logical structure is unsurpassed. The chapter arrangement of this book largely follows this work.

Wang Shuhe, in compiling Zhang Zhongjing's *Shanghan Lun*, established chapters for the Three Yang and Three Yin channels. His rule for the Three Yang chapters was: any condition Zhang Zhongjing termed "Taiyang Disease" was placed in the Taiyang chapter; "Yangming Disease" in the Yangming chapter; and "Shaoyang Disease" in the Shaoyang chapter. The Three Yin chapters followed the same logic, categorizing diseases under their respective names: Taoyin, Shaoyin, and Jueyin. However, if Zhang Zhongjing did not use these channel names but instead described a specific disease or formula within mixed chapters, conditions belonging to Yang syndromes—such as fever, chest binding (Jie Xiong), epigastric fullness/stuffiness (Pi Qi), blood stasis (Xu Xue), and nasal bleeding (Nü Xue)—were grouped into the Taiyang chapter. Conditions belonging to Yin syndromes—such as cold extremities (Jue Ni), diarrhea (Xia Li), and vomiting (Ou Tu)—were grouped into the Jueyin chapter. Exceptions included conditions like dry feces, hard stool, inability to defecate, and difficult defecation, which were uniquely placed in the Yangming chapter because they belong to Yangming Stomach Excess (Wei Shi) and do not fit Taiyang or Jueyin. This is because Taiyang is the head of the Three Yang; all Yangming and Shaoyin diseases typically transmit from Taiyang, so uncategorized Yang conditions were placed there. Conversely, Jueyin is the tail of the Three Yin; all Taoyin and Shaoyin diseases eventually transmit to Jueyin, so uncategorized Yin conditions were placed there. Later scholars failed to understand this principle, mistakenly assuming that uncategorized conditions in the Taiyang chapter belonged to Taiyang disease, thus distorting the true nature of Taiyang pathology, and similarly misinterpreting Jueyin chapter conditions, greatly deviating from Zhang Zhongjing's methodology. In this book, regarding the classification of symptoms by channel, we largely retain Wang Shuhe's original arrangement, but learners should strive to comprehend the underlying logic clearly.

Zhang Zhongjing established diagnostic criteria: whenever he stated "Taiyang Disease," he referred to floating pulse (Mai Fu), stiffness and pain in the head and neck (Tou Xiang Qiang Tong), and aversion to cold (E Han). "Yangming Disease" referred to Stomach Excess (Wei Jia Shi). "Shaoyang Disease" referred to bitter taste in the mouth (Kou Ku), dry throat (Yan Gan), and vertigo/blurred vision (Mu Xuan). "Taoyin Disease" referred to abdominal fullness (Fu Man), intermittent pain (Shi Tong), vomiting, and diarrhea (Tu Li). "Shaoyin Disease" referred to faint and thin pulse (Mai Wei Xi) and a desire to sleep (Dan Yu Mei). "Jueyin Disease" referred to qi rushing upward striking the heart (Qi Shang Zhuang Xin), heart pain (Xin Zhong Teng Re), and vomiting roundworms (Tu Hui). Since Shaoyin Disease manifests in various ways, Zhang Zhongjing did not repeat "faint pulse and desire to sleep" for every clause but used the term "Shaoyin Disease" as an abbreviation. For instance, when he wrote "Shaoyin Disease with reversed fever and deep pulse, use Mahuang Fuzi Xixin Tang," it implies a patient presenting with faint/deep pulse and desire to sleep, who additionally exhibits fever. Similarly, "Shaoyin Disease developing after two or three days, with restlessness and inability to sleep, use Huanglian Ejiao Tang" applies to patients who initially had Shaoyin signs but developed restlessness and insomnia. Later scholars misunderstood this, failing to recognize the core Shaoyin syndrome covered by the term, and indiscriminately using Mahuang Fuzi Xixin Tang for any fever with deep pulse, or Huanglian Ejiao Tang for any restlessness, a grave deviation from Zhang Zhongjing's method.

Among commentators on Zhang Zhongjing's works, Cheng Wuji is the most detailed. Although his line-by-line explanations occasionally contain contradictions, these are minor flaws in an otherwise invaluable treasure. Later scholars such as Zhao Sizhen, Zhang Jianshan, and others made significant contributions, serving as loyal followers to Cheng's work. I have extensively quoted them to allow students to gain clear insight, occasionally adding my own humble observations. Where the text is self-explanatory, I have omitted redundant annotations. Abbreviations used: Zhao refers to Sizhen; Zhang to Jianshan; Huang to Zhongli; "Huo" to Zhu Gong's *Huoren Shu* (Living Person's Book); Pang to Anshi; Xu to Shuwei Xueshi; "Ben" to Xu Shuwei's *Benshi Fang*; Han to He; Sun to Zhao; Jie to Jiegu Zhang Yuansu; Yun to Yunqizi, son of Jiegu; Yuan to Li Dongyuan; Dan to Zhu Danxi; Hai to Wang Haizang; Wang to Lü; Luo to Tianyi; Dai to Yuanli; Lou to Quanshan; Wu to Shou; Tao to Hua. Texts not attributed to these surnames, except for the initial diagnostic statements, are direct quotes from Zhang Zhongjing.

Zhang Zhongjing's prescriptions often used units like jin (catty), sheng (peck), he, and mei. Due to differences in ancient and modern weights and measures, direct application is difficult. Official texts like *Ju Fang* and *Gangmu* reduced dosages significantly (e.g., five qian per dose), making them too small. Scholars like Tao Hua and Wu Shou altered ancient formulas to suit contemporary practices, introducing further errors. This book retains Zhang Zhongjing's original dosage units, advising practitioners to adjust based on patient condition and season. Ancient formulas should be applied flexibly, not just Zhang's. Chen Wuyue's use of coin specifications to estimate measurements is practical; I cite his views here for reference.

Regarding length: Fen, Cun, Chi, Zhang, and Yin were originally defined by grain sizes. Modern rulers vary: Zhou chi (8 cun), Jing chi (16 cun), Huai chi (12 cun), Yue chi (12.5 cun). We use the smaller standard. Tang Kaiyuan Tongbao coins (diameter 8 fen) provide a reference. Regarding volume: He, Sheng, Dou, and Hu were based on the Huangzhong pitch pipe. One He weighed 24 zhu. Song dynasty standards varied; one Song sheng equaled five Han sheng. Regarding weight: Zhu, Liang, Jin, Jun, and Shi were also based on the Huangzhong pipe. One Liang was 24 Zhu. Han coins ("Ban Liang") and Tang coins ("Kaiyuan Tongbao") differ in weight. Historical records suggest Han Liang was heavier than Tang Liang. *Qianjin Yaofang* and *Bencao* equate ancient 3 Liang to modern 1 Liang. Calculating exact conversions is complex. For example, Ban Xia (Pinellia Rhizome) 1 Sheng equals 5 Liang, but which Sheng and Liang? This is crucial for compounding. Han coins evolved; Wuzhu coins were standardized. It is believed Han 1 Liang equaled two Ban Liang coins (10 Zhu). Tang 1 Liang equaled 24 Zhu. Comparing coin weights helps estimate: 16 Wuzhu coins equal 10 Kaiyuan coins in weight. Ancient herbal decoctions used large amounts of herbs (30+ Liang) and water (6-7 Sheng), boiled down to 2-3 Sheng. Applying ancient weights directly to modern practice may result in overdose or underdose. Wu Shou suggests: 24 Zhu = 1 Liang; 1 Liang = 4 Fen; 6 Zhu = 1 Fen (approx. 2.5 Qian). 1 Qian = 4 Zi; 1 Zi = 2.5 Li. Practitioners must adapt to individual constitution, season, and location. For example, Daxiexiong Tang uses 6 Liang of Dahuang; today, 6 Qian may suffice for mild cases, less for weak patients. Mangxiao (Mirabilite) 1 Sheng might be 2-3 Qian today. Gansui (Kansui Root) 2 Liang might be 1 Fen today. Rigidity leads to death; flexibility saves lives.

The *Neijing* states: "Wind, rain, cold, and heat cannot harm alone unless deficiency exists." Zhu Danxi argued that most Shanghan cases stem from internal injury (Neishang) and require tonifying Yuan Qi. Consequently, some physicians, lacking full understanding of Zhang Zhongjing's methods, mistakenly treated Shanghan as pure deficiency and used tonic therapies, or conversely, used harsh sweating/purging on deficient patients, leading to death. This is akin to murder. Although I include later tonic methods, I emphasize that clinical judgment requires deep study and caution. Protect Yuan Qi; avoid reckless sweating or purging.

Tu Peng in *Sishi Zhiyao* advises distinguishing Yin and Yang through pulse, form, respiration, and voice. Before administering strong formulas like Dachengqi Tang, test with Xiao Chengqi Tang first. Before Da Chaihu Tang, test with Xiao Chaihu Tang. For Yin syndromes requiring Sini Tang, test with Lizhong Tang or Zhenwu Tang first. This cautious approach is wisdom. However, medicine determines life and death instantly; "testing" carries risks. Zhang Rui, a Song dynasty master, treated a Shanghan case with extreme heat. He prepared Chengqi Tang but hesitated repeatedly. The patient suddenly shook, covered himself with blankets, sweated profusely, and recovered spontaneously. Had he taken the medicine, he would have died. Thus, while Tu Peng's caution is not Zhang Zhongjing's original intent, it serves as a warning against rash action by mediocre doctors.