古吴 叶桂天士 述 后学 吴金寿子音 校
伤寒之病，不外六经，欲明六经，当知其要。要者何。定其名，分其经，审其症，察其脉，识阴阳，明表里，度
虚实，之标本者，是也。定其名者，是定其正伤寒、或感冒、与风温、温毒之类也。分其经者，是分其阳经、
阴经、直中之类。审其症者，是审其阳症、阴症、表症、里症、虚症、实症、寒症、热症之原。察其脉者，是察其
有力、无力、及浮、沈、迟、数、弦、滑之类也。识阴阳者，谓识其阳病、阴病、阳虚、阴虚之候。名表里者，是明其
在表、在里、或在半表半里之间。度虚实者，是度其表虚、里虚、表实、里实之病耳。知标本者，欲知其一
经之中，而有标病、本病之类也。诚能若是，可谓知其要矣。既知其要，则仲景三百九十七法，一百一
十三方，不出握中矣。何患症之不明，病之难愈哉。经曰、知其要者，一言而终，不知其要，流散无穷。又
曰、知其要者，万举万当，不知其要，则支离破碎。犹涉海而问津，故曰伤寒要书。
足太阳膀胱经，乃诸阳之首，故多传变受病者为先，其脉起于目内皆，从头下后项，连风府，行身之
背，终于左足外踝，故头项痛，腰脊强。发热恶寒，尺寸俱浮者，太阳经受病也。若头痛发热，汗出恶风
是风伤?气，乃表虚，宜解肌，桂枝汤主之。若头痛发热，无汗恶寒，是寒伤营血，乃表实，宜发散，麻黄
汤主之。头痛、发热、恶寒者，此太阳表症，标病也。不拘日数多少，便宜发散。若发热烦渴，小便不利者，
此太阳本府受病也，宜利小便，五苓散主之。若小便利者，不可再利，利之则引热入里，而为热结膀
胱、其人如狂等症。又不可下，下之则表邪乘虚入里，而为痞满结胸、协热下痢等症。故曰太阳经症
切不可下，下之则表邪乘虚内陷，而传变不可胜数。又不可利小便，利之则引邪入里，其害不浅。又
曰、有汗不可服麻黄汤，无汗不可服桂枝汤。又曰、有汗不可再汗，汗多不可利小便也。
伤寒病，不外乎六经（六条主要经络及其所属脏腑的病理变化），想要明白六经，应当掌握其要点。要点是什么？确定病名，区分经络，审查症状，诊察脉象，识别阴阳，明确表里，度量虚实，知晓标本，就是这样。确定病名，是确定属于正伤寒、还是感冒、以及风温、温毒之类的疾病。区分经络，是区分阳经、阴经、以及直中（病邪直接侵入脏腑）之类。审查症状，是审查阳证、阴证、表证、里证、虚证、实证、寒证、热证的根源。诊察脉象，是诊察脉象有力、无力，以及浮、沉、迟、数、弦、滑等类型。识别阴阳，是指识别阳病、阴病、阳虚、阴虚的征候。明辨表里，是明确病位在表、在里、或在半表半里之间。度量虚实，是度量表虚、里虚、表实、里实的病情罢了。知晓标本，是想了解在一经之中，有标病、本病之类的区别。如果能做到这些，可以说是掌握了要领。既然掌握了要领，那么张仲景的三百九十七种治法，一百一十三首方剂，就不出掌握之中了。还担心什么症状不明白，病情难治愈呢？经文说：知道要领的人，一句话就能终结（道理），不知道要领，就会流散无穷。又说：知道要领的人，万举万当（每次行动都恰当），不知道要领，就会支离破碎。就像渡海却不知渡口在哪里，所以称这本书为《伤寒要书》。
足太阳膀胱经，是诸阳经之首，所以多传变受病的往往以此为始。它的脉气起于目内眦，从头下行至后项，连接风府穴，行于背部，终于左足外踝，所以出现头项痛、腰脊强直。发热恶寒，寸关尺三部脉象都浮的，是足太阳膀胱经受病。如果头痛发热，汗出恶风，这是风邪伤卫气，属于表虚，宜用解肌法，以桂枝汤为主治。如果头痛发热，无汗恶寒，这是寒邪伤营血，属于表实，宜用发散法，以麻黄汤为主治。头痛、发热、恶寒，这是太阳表证，属于标病。不论患病天数多少，都应当及时发散。如果发热烦渴，小便不利，这是太阳的本腑（膀胱）受病，宜利小便，以五苓散为主治。如果小便利，不可再利小便，利之则引热入里，导致热结膀胱、其人如狂等症状。又不可用下法，下之则表邪乘虚入里，导致痞满、结胸、协热下痢等症状。所以说太阳经证切不可用下法，下之则表邪乘虚内陷，传变不可胜数。又不可利小便，利之则引邪入里，危害不浅。又说：有汗不可服麻黄汤，无汗不可服桂枝汤。又说：有汗不可再发汗，汗多不可利小便。
Narrated by Ye Gui (Courtesy Name: Tianshi) of Guwu, and collated by Wu Jinshou (Courtesy Name: Ziyin), a junior scholar.
The disease of Shanghan (Cold Damage) does not go beyond the Six Channels (the six major meridians and their associated organ systems). To understand the Six Channels, one must grasp their essentials. What are these essentials? They are: determining the disease name, differentiating the meridians, examining the symptoms, inspecting the pulse, recognizing Yin and Yang, clarifying exterior and interior, assessing deficiency and excess, and knowing the root and branch. Determining the disease name refers to distinguishing between Zheng Shanghan (True Cold Damage), Ganmao (Common Cold), Fengwen (Wind-Warmth), Wendu (Warm-Toxin), and similar conditions. Differentiating the meridians involves distinguishing between Yang meridians, Yin meridians, and direct invasion (Zhizhong, where pathogenic factors directly invade the zang-fu organs). Examining symptoms entails analyzing the origins of Yang syndromes, Yin syndromes, Exterior syndromes, Interior syndromes, Deficiency syndromes, Excess syndromes, Cold syndromes, and Heat syndromes. Inspecting the pulse involves observing whether the pulse is forceful or forceless, and identifying types such as Floating (Fu), Deep (Chen), Slow (Chi), Rapid (Shu), Wiry (Xian), and Slippery (Hua). Recognizing Yin and Yang means identifying the manifestations of Yang diseases, Yin diseases, Yang deficiency, and Yin deficiency. Clarifying exterior and interior means understanding whether the pathology is located in the Exterior, Interior, or at the Half-Exterior Half-Interior level. Assessing deficiency and excess involves evaluating Exterior deficiency, Interior deficiency, Exterior excess, and Interior excess conditions. Knowing the root and branch refers to understanding within a single channel the distinctions between Branch diseases (Biao, often acute or superficial manifestations) and Root diseases (Ben, often chronic or internal origins). If one can achieve this, it can be said that one has grasped the essentials. Once the essentials are grasped, Zhang Zhongjing’s 397 treatment methods and 113 prescriptions will be well within one's control. How could there be worry about unclear symptoms or incurable diseases? The Classic states: "He who knows the essentials, finishes with one word; he who does not know the essentials, wanders endlessly." It also states: "He who knows the essentials, succeeds in every attempt; he who does not know the essentials, becomes fragmented and confused." This is like crossing a sea without knowing the ferry crossing. Therefore, it is called the *Essential Book of Shanghan*.
The Foot-Taiyang Bladder Meridian is the head of all Yang meridians; thus, it is often the first to undergo transmission and contract disease. Its pulse originates from the inner canthus of the eye, descends from the head to the nape of the neck, connects to the Fengfu point (GV16), runs along the back of the body, and terminates at the lateral malleolus of the left foot. Consequently, it presents with headache and stiffness of the neck and lower back. Fever with aversion to cold, accompanied by a Floating pulse in all three positions (Cun, Guan, Chi), indicates disease of the Foot-Taiyang Bladder Meridian. If there is headache, fever, sweating, and aversion to wind, this is Wind injuring the Wei-Qi (Defensive Qi), representing an Exterior Deficiency syndrome. It is suitable for the method of resolving the muscle layer (Jieji), primarily treated with Guizhi Tang (Cinnamon Twig Decoction). If there is headache, fever, absence of sweating, and aversion to cold, this is Cold injuring the Ying-Blood (Nutritive Blood), representing an Exterior Excess syndrome. It is suitable for the method of dispersing and diffusing (Fasan), primarily treated with Mahuang Tang (Ephedra Decoction). Headache, fever, and aversion to cold constitute a Taiyang Exterior Syndrome, which is a Branch disease. Regardless of the number of days since onset, it should be promptly dispersed. If there is fever, irritability, thirst, and difficulty urinating, this is disease of the Root Organ (Bladder) of Taiyang. It is suitable for promoting urination, primarily treated with Wuling San (Five-Ingredient Powder with Poria). If urination is normal, do not promote urination again; doing so draws heat into the Interior, leading to Heat Binding in the Bladder and symptoms such as mania-like behavior. Furthermore, purgation (Xia) must not be used; if used, the Exterior pathogen enters the Interior due to deficiency, leading to fullness and obstruction, Chest Bind (Xiexiong), and dysentery with concurrent heat. Therefore, it is stated that Taiyang Channel syndromes must absolutely not be treated with purgation. Purgation causes the Exterior pathogen to sink inward due to deficiency, resulting in countless variations of transmission. Promoting urination is also contraindicated, as it draws the pathogen into the Interior, causing significant harm. It is also stated: Those with sweating must not take Mahuang Tang; those without sweating must not take Guizhi Tang. It is further stated: Those with sweating must not induce sweating again; those with excessive sweating must not promote urination.