《经》言∶寒伤形，寒伤皮毛，寒伤血。然寒主闭藏，而腠理 密，阳气怫郁，不能通畅，怫然内作，故身热燥而
无汗。故《经》曰∶人之伤于寒也，则为热病。又曰∶夫热病，皆伤寒之类也。《内经》既直言热病者，言一身为病之
热气也。以至仲景直言伤寒者，言外伤之寒邪也。以分风寒暑湿之所伤，主疗不同，故只言伤寒，而不通言热病也。其
寒邪为害至大，故一切内外所伤，俱为受寒之热病者，通谓之伤寒也。一名大病者，皆以为害之大也。又春曰温病，夏
曰热病，秋曰湿病，冬曰伤寒。伤寒者，是随四时天气，春温，夏热，秋湿，冬寒为名，以明四时病之微甚，及主疗消
息稍有不等，大而言之则一也。非为外伤及内病有此异耳。或云冬伏寒邪于肌肤骨肉之间，至于春变为温病，夏变为热
病，秋变为湿病，冬变病为正伤寒病者；及名冒其寒，而内生怫热，热微而不即病者；以至将来阳热变动，或又感之而
成热病；非谓伏其寒气，而反变寒为热也。《经》曰∶“冬伤于寒，春必病温”，亦其义也。亦有一时冒寒而便为热病者，
或感四时不正乖戾之气；或随气运兴衰变动；或内外诸邪所伤；或因他病变成；或因他人传染。皆能成之，但以分门随
证治之耳。《经》言此六经传受，乃外伤于寒，而为热病之大略，主疗之要法也。（《伤寒六经传受》）
The *Classic* states: Cold damages the form, cold damages the skin and hair follicles (mao-fu), and cold damages the blood. However, cold governs closure and storage, causing the interstices (cou-li) to be dense, leading to the stagnation of Yang Qi, which cannot flow smoothly. This stagnation arises internally, resulting in fever, dryness, and anhidrosis. Therefore, the *Classic* says: When humans are injured by cold, it becomes a heat disease (Re Bing). It also states: All heat diseases belong to the category of Cold Damage (Shang Han). Since the *Nei Jing* directly refers to "heat disease," it denotes the pathological heat qi affecting the entire body. As for Zhang Zhongjing's direct reference to "Cold Damage," it denotes the external pathogenic cold evil. This distinction is made because wind, cold, summer-heat, and dampness cause different injuries requiring different treatments; thus, only "Cold Damage" is mentioned, not the general term "heat disease." The harm caused by cold evil is significant; therefore, all injuries from internal and external sources that result in heat conditions due to cold exposure are collectively referred to as "Cold Damage." Another name for it is "Major Disease" (Da Bing), indicating its severe harm. Furthermore, diseases occurring in spring are called Warm Diseases (Wen Bing), those in summer are called Heat Diseases (Re Bing), those in autumn are called Damp Diseases (Shi Bing), and those in winter are called Cold Damage (Shang Han). "Cold Damage" is named according to the seasonal weather patterns—spring warmth, summer heat, autumn dampness, winter cold—to clarify the severity of diseases in the four seasons and the slight variations in treatment principles. Broadly speaking, they are one and the same. It does not imply a difference between external injuries and internal diseases. Some argue that cold evil latent in the skin, muscles, bones, and flesh during winter transforms into Warm Disease in spring, Heat Disease in summer, Damp Disease in autumn, and proper Cold Damage in winter. Others mention contracting cold, generating internal stagnated heat, where the heat is mild and does not immediately manifest as disease, or where future Yang heat changes occur, or additional infections lead to heat disease. This does not mean the latent cold qi transforms into heat. The *Classic* says: "If injured by cold in winter, Warm Disease will inevitably occur in spring," which aligns with this principle. There are also cases where immediate contraction of cold leads to heat disease, or contraction of abnormal and perverse Qi of the four seasons, or changes driven by the rise and fall of Qi dynamics, or injuries from various internal and external evils, or transformation from other diseases, or transmission from others. All can result in disease, but they are treated according to their categories and specific manifestations. The *Classic*'s discussion on the transmission through the Six Channels (Liu Jing) outlines the general pattern of external cold injury leading to heat disease and serves as the essential method for treatment. (*Transmission of Cold Damage through the Six Channels*)