汉长沙着《伤寒论》，以治风、寒、暑、湿、燥、火六气之邪，非仅为寒邪而设。然则其书名伤寒何
也？盖缘十二经脉，惟足太阳在表，为寒水之经，凡六淫之邪为病者，皆必先伤于寒水之经，故曰伤寒。
今人都以寒水之寒字，误为寒热之寒，若此则伤寒之书，专治寒邪，而风、暑、燥、湿、火，了不干涉矣。
殊不思长沙首列桂枝汤以治风，明明指人统治六气，而非仅治一寒邪之意，于此已露一斑。若果专治寒邪，
理当列麻黄汤、附子汤、四逆、理中等汤为先，而不列桂枝汤为首也。况又有白虎汤以治暑，五苓散以治湿，
炙甘草汤以治燥，大小承气以治火，此显明六气统治之书，而今以为专治寒邪，则误甚矣。时贤又谓伤寒论六
经，温热论三焦，此两句书，更为印定眼目。不知邪气袭人，皆由表而入于里，惟温疫之气，秽浊之气，乃论
三焦可也。以其气从口鼻而入，先扰于上，次传中下，除此而外，则风、寒、暑、湿、燥、火，无不尽从表
入。况李 谓“太阳行身之表，外邪皆得伤之”。其伤寒之书，能统治六气者，可无疑矣。凡学治时病者，
必须读仲景《伤寒论》，参读时贤之书，考古酌今，则胸中自有风、寒、暑、湿、燥、火之界限。若不
读仲景之本，而专读时贤之书，真所谓舍本求末矣。
汉代长沙太守张仲景撰写《伤寒论》，旨在治疗风、寒、暑、湿、燥、火这六气之邪，并非仅仅为了治疗寒邪而设立。那么，为什么这本书命名为《伤寒论》呢？大概是因为在十二经脉中，只有足太阳膀胱经位于体表，属于寒水之经，凡是六淫（风、寒、暑、湿、燥、火六种外感病邪）致病，都必定先损伤寒水之经（即足太阳经），所以称之为“伤寒”。
如今的人都将“寒水”的“寒”字，错误地理解为“寒热”的“寒”，如果这样理解，那么《伤寒论》就专门治疗寒邪，而与风、暑、燥、湿、火完全无关了。殊不知张仲景首先列出桂枝汤来治疗风邪，这明明是指出了该书能统摄治疗六气，而非仅治疗单一寒邪的意思，从这里已经可以看出端倪。如果真的只治疗寒邪，按理应当将麻黄汤、附子汤、四逆汤、理中汤等列为首选，而不是将桂枝汤列为首方。况且书中还有白虎汤用来治疗暑邪，五苓散用来治疗湿邪，炙甘草汤用来治疗燥邪，大承气汤和小承气汤用来治疗火邪，这明显是一部能够统摄治疗六气的著作，而今人却认为它专门治疗寒邪，那就错得厉害了。
当时的名医又提出《伤寒论》讲六经，《温热论》讲三焦，这两句话更是束缚了人们的思想。不知道邪气侵袭人体，都是从表进入里，只有温疫之气、秽浊之气，才适合用三焦辨证来论述。因为这些邪气从口鼻而入，先扰乱上焦，然后传变至中焦和下焦。除此之外，风、寒、暑、湿、燥、火，无不都是从体表侵入。况且李时珍曾说：“太阳经行于身体之表，外邪都能伤害它。”由此可知，他的《伤寒论》一书，确实能够统摄治疗六气，这是毫无疑问的。
凡是学习诊治时令疾病的人，必须研读张仲景的《伤寒论》，并参考当时名医的著作，考证古代、斟酌现代，那么心中自然就有风、寒、暑、湿、燥、火的界限。如果不读张仲景的根本经典，而专门阅读当时名医的著作，真可以说是舍弃根本而追求末节了。
In the Han Dynasty, Zhang Zhongjing, the Grand Administrator of Changsha, authored *Shanghan Lun* (Treatise on Cold Damage Diseases) to treat pathogens of the six qi (Six Climatic Factors: Wind, Cold, Summer-heat, Dampness, Dryness, and Fire), not merely for the purpose of treating Cold pathogen. Then why is the book named *Shanghan Lun*? It is because among the twelve meridians, only the Foot-Taiyang Bladder Meridian is located at the exterior and belongs to the Water-Cold meridian. Whenever diseases are caused by the six excesses (Liuyin, the six climatic factors acting as pathogens), they invariably first injure the Water-Cold meridian; hence it is called "Shanghan" (Cold Damage).
Modern people mistakenly interpret the character "Han" (Cold) in "Water-Cold" as referring to "Cold-Heat" differentiation. If this interpretation were correct, then *Shanghan Lun* would exclusively treat Cold pathogen, having no relevance to Wind, Summer-heat, Dryness, Dampness, or Fire. Little do they realize that Zhang Zhongjing listed Guizhi Tang (Cinnamon Twig Decoction) first to treat Wind, clearly indicating that the book governs the treatment of all six qi, rather than just a single Cold pathogen. This is evident from the very beginning. If it truly treated only Cold pathogen, logic would dictate listing Mahuang Tang (Ephedra Decoction), Fuzi Tang (Aconite Decoction), Sini Tang (Frigid Extremities Decoction), and Lizhong Tang (Regulate the Middle Decoction) as primary formulas, rather than placing Guizhi Tang first. Moreover, the text includes Baihu Tang (White Tiger Decoction) to treat Summer-heat, Wuling San (Five-Ling Powder) to treat Dampness, Zhigancao Tang (Honey-Fried Licorice Decoction) to treat Dryness, and Dachengqi Tang (Major Order the Qi Decoction) and Xiaochengqi Tang (Minor Order the Qi Decoction) to treat Fire. This explicitly demonstrates that it is a book governing the treatment of the six qi. To regard it now as exclusively treating Cold pathogen is a significant error.
Contemporary scholars further assert that *Shanghan Lun* discusses the Six Meridians (Liu Jing), while *Wenre Lun* (Treatise on Warm Heat) discusses the Triple Burner (San Jiao). These two statements have further confined scholarly perspective. One should understand that pathogens invading the human body enter from the exterior into the interior. Only the Qi of Warm Epidemics (Wenyi) and turbid/filthy Qi are appropriately discussed via the Triple Burner differentiation, as these pathogens enter through the mouth and nose, first disturbing the Upper Burner, then transmitting to the Middle and Lower Burners. Apart from these, Wind, Cold, Summer-heat, Dampness, Dryness, and Fire all enter from the exterior. Furthermore, Li Shizhen stated, "The Taiyang meridian runs along the exterior of the body, and external pathogens can all injure it." Thus, there is no doubt that his *Shanghan Lun* can govern the treatment of the six qi.
Those who study and treat seasonal diseases must read Zhang Zhongjing's *Shanghan Lun* and reference the works of contemporary experts. By examining ancient texts and considering modern practices, one will naturally discern the boundaries between Wind, Cold, Summer-heat, Dampness, Dryness, and Fire. If one does not read Zhang Zhongjing's foundational classic but instead specializes only in the works of contemporary experts, it is truly described as abandoning the root to pursue the branches.