经曰∶冬伤于寒。谓交立冬之后，寒气伤人。其能固密者，何伤之有？一有不谨，则寒遂伤于寒水之经，
即病寒热无汗，脉来浮紧，名曰伤寒是也。一交春令，便不可以伤寒名之。然冬令受寒，有浅深之别焉，深
者为中，浅者为冒。盖中寒者，寒邪直中于三阴之里，故有吐泻腹痛，急宜热剂祛寒。冒寒者，寒邪冒于躯
壳之外，则有寒热身疼，不难一汗而愈。伤寒、中寒、冒寒，略述其概。犹有冬温之证，不可不详。冬温者，
冬应寒而反温，非其时而有其气，人感之而即病者是也。宜用辛凉之法，慎勿误用麻、桂、青龙，若误用之，
必变证百出矣。此四者，乃冬时即病之新感也，倘受微寒微温之气，当时未发，必待来春而发者，便是伏气
之病，须别诸温而治之。
或问曰∶曾见东垣之书，已有冬伤于寒，春必病温等论。先生拾前人之唾余，竟以为独开生面之创，欺人
乎？抑亦自欺之甚也？答曰∶子言过矣！丰亦见《此事难知》之内，有论四篇，所云都是五行生克有余不足，
所胜所不胜之理，其义难明，诚难知之书也。丰今分论八篇，以为时证提纲，其理透彻，阅
者易知，明出冬伤于寒之新感，所见何证；冬伤于寒，春必病温之伏气，所见何证；一一详明，了如指掌。
与东垣之论，意思悬殊，何尝拾其唾余，以为己出耶！此犹应试，共一题目，而文本
实不雷同，奚敢欺人复自欺耳！然乎否乎？
《黄帝内经》中说：“冬季感受寒邪。”指的是在立冬节气之后，寒气侵袭人体。如果人体正气固密，有什么可伤害的呢？一旦稍有疏忽不慎，寒气就会侵犯属水的经脉（即足少阴肾经等），立即出现寒热交替、无汗的症状，脉象浮紧，这就叫做伤寒。
一到春季，就不能再称之为伤寒了。然而，冬季受寒有深浅的区别：深者为“中寒”，浅者为“冒寒”。所谓中寒，是指寒邪直接侵入三阴经的脏腑内部，因此会出现呕吐、腹泻、腹痛等症状，急需使用温热药物来祛除寒邪。所谓冒寒，是指寒邪侵袭体表躯壳之外，会出现恶寒发热、身体疼痛，不难通过发汗的方法治愈。以上简要阐述了伤寒、中寒、冒寒的大概情况。此外还有冬温这一证候，不可不详细论述。冬温，是指冬季本该寒冷却反而温暖，非其时而有其气，人感受这种气候而立即发病的情况。应当使用辛凉解表的方法治疗，千万不要误用麻黄汤、桂枝汤或大青龙汤，如果误用这些方剂，必然会导致各种变证出现。
这四种情况（伤寒、中寒、冒寒、冬温），属于冬季当时感邪随即发病的新感病。倘若感受轻微的寒邪或温邪，当时没有发作，必须等到来年春天才发作的，就是伏气温病，需要按照不同的温病类型进行治疗。
有人问道：“我曾见过李东垣的著作中，已有‘冬伤于寒，春必病温’等论述。先生您拾取前人的余唾，竟然认为是独辟蹊径的创新，这是欺骗别人呢，还是自欺欺人呢？”我回答说：“你这话错了！我也见过《此事难知》这本书，里面有四篇论述，所说的都是五行生克有余不足、所胜所不胜的道理，含义难以明白，确实是一本难懂的书。我现在分论八篇，作为时令病证的提纲，道理透彻，读者容易理解，明确区分出冬伤于寒的新感病所见何证；以及冬伤于寒、春必病温的伏气病所见何证，一一详细阐明，如同看手掌一样清楚。这与李东垣的论述，意思截然不同，何曾拾取他的余唾当作自己的成果呢！这就像参加科举考试，共用一个题目，但文章实质并不雷同，怎敢说是欺骗别人又欺骗自己呢！你说得对吗？”
The *Classic of Internal Medicine* states: "In winter, one is injured by cold." This refers to the invasion of cold pathogenic factors into the human body after the solar term of Start of Winter. If the body's righteous qi is solid and dense, what harm can there be? However, if one is even slightly negligent, the cold will injure the meridians associated with water (i.e., the Foot Shaoyin Kidney meridian), immediately presenting with alternating chills and fever, absence of sweating, and a floating and tight pulse; this is named Cold Damage (Shanghan).
Once spring arrives, it can no longer be termed Cold Damage. Nevertheless, contracting cold in winter has distinctions of depth: deep contraction is called "Zhong Han" (Mid-Cold), while shallow contraction is called "Mao Han" (Covered-Cold). Zhong Han occurs when cold pathogens directly invade the interior of the Three Yin meridians (Taiyin, Shaoyin, Jueyin), thus manifesting as vomiting, diarrhea, and abdominal pain; it urgently requires hot-natured decoctions to dispel cold. Mao Han occurs when cold pathogens cover the exterior of the body shell, manifesting as aversion to cold, fever, and body ache, which is not difficult to cure through diaphoresis (sweating). The above briefly outlines the general concepts of Cold Damage, Mid-Cold, and Covered-Cold. Additionally, there is the syndrome of Winter-Warmth (Dong Wen), which must be detailed. Winter-Warmth refers to a situation where winter should be cold but is instead warm; non-seasonal qi prevails, and upon exposure, illness ensues immediately. One should employ acrid-cool methods; strictly avoid misusing Mahuang Tang (Ephedra Decoction), Guizhi Tang (Cinnamon Twig Decoction), or Da Qinglong Tang (Major Green Dragon Decoction). Misuse will inevitably lead to myriad transformation syndromes.
These four conditions represent new acquisitions contracted during winter that manifest immediately. Conversely, if one contracts slight cold or warmth, which does not manifest at the time but waits until the following spring to erupt, this constitutes a latent Qi disease (Fu Qi Bing), which must be treated according to various categories of Warm Diseases.
A questioner asked: "I have seen in Dongyuan’s [Li Dongyuan] works discussions such as 'Winter injury by cold leads to warmth diseases in spring.' Have you merely picked up the dregs of predecessors' spittle, yet claiming it as an innovative breakthrough? Are you deceiving others, or are you severely deceiving yourself?" I replied: "Your words are excessive! I too have seen the book *Ci Shi Nan Zhi* (Difficulties of This Matter), which contains four treatises discussing the principles of excess and deficiency in the generation and restriction cycles of the Five Elements, and the relationships of being overcome and overcoming. Their meanings are obscure, making it indeed a difficult book to understand. I now divide the discussion into eight chapters to serve as an outline for seasonal syndromes. The logic is thorough, making it easy for readers to comprehend. I clearly distinguish the syndromes presented by new acquisition from winter cold injury; and the syndromes presented by latent qi from winter cold injury leading to spring warmth disease, detailing them one by one with clarity like seeing the palm of one's hand. This differs significantly in meaning from Dongyuan’s discussion. How could I possibly pick up his dregs and claim them as my own? It is akin to taking an examination with the same topic, yet the essays are substantially different. How dare I claim to deceive others and myself? Is this not so?"