伤寒初起，先发热而后恶寒；疫症初起，先恶寒
而后发热，一两日后，但热而不恶寒。此寒热同而先后异也。有似太阳、阳明者，然太阳、阳明，头痛不
至如破，而疫则头痛如劈，沉不能举。伤寒无汗，而疫则下体无汗，上身有汗，惟头汗更盛。头为诸阳之
首，火性炎上，毒火盘踞于内，五液受其煎熬，热气上腾，如笼上熏蒸之露，故头汗独多。此又痛虽同，
而汗独异也。有似少阳呕者，有似太阴自利者。少阳而呕，胁必痛，耳必聋；疫症之呕，胁不痛，耳不
聋，因内有伏毒，邪火干胃，毒瓦斯上冲，频频而作。太阴自利者，腹必满；疫症自利者，腹不满。大肠为传
送之官，热注大肠，有下恶垢者，有旁流清水者，有日及数十度者。此又症异而病同也。种种分别是疫，
奈何犹执伤寒治哉？
仲景论冬至后为正伤寒，可见非冬至后，不过以类推其治耳！其言伤寒重在“冬至后”三字。世人论
仲景书，究心七十二症，至于“冬至后”三字，全不体贴，是以无论春、夏、秋、冬，俱以伤寒治之。要
之四时之气，寒特一耳。以冬月因寒受病，故曰伤
寒。至春而夏，由温而热，亦曰伤寒，不知寒从何伤？予每论热疫不是伤寒，伤寒不发斑疹。有人问
曰∶子言热疫不是伤寒，固已！至云伤寒不发斑疹，古人何以谓伤寒热未入胃，下之太早，热乘虚入胃，
故发斑；热已入胃，不即下之，热不得泄，亦发斑。斯何谓也？曰∶此古人立言之误也。即“热”之一字
以证其非，热与寒相反而不相并者。既云伤寒，何以有热入胃？又曰热已入胃，何以谓之伤寒？即用白虎、
三黄、化斑、解毒等汤，俱从热治，未作寒医，何今人不悟古人之误，而因以自误而误人也？至论大者为
斑，小者为疹，赤者胃热极，五死一生，紫黑者胃烂，九死一生，予断生死，则又不在斑之大、小、紫、黑，
总以其形之松浮、紧束为凭耳。如斑一出，松活浮于皮面，红如朱点纸，黑如墨涂肤，此毒之松活外现
者，虽紫黑成片可生；一出虽小如粟，紧束有根，如履底透针，如矢贯的，此毒之有根锢结者，纵不紫黑
亦死，苟能细心审量，神明于松浮紧束之间，决生死于临症之顷，始信予言之不谬也。
伤寒病初起时，先出现发热，随后才出现恶寒；疫病初起时，先出现恶寒，随后才出现发热，一两天后，只发热而不恶寒。这是寒热症状相同但出现的先后顺序不同。有的表现类似太阳病（太阳经受邪所致的病证）和阳明病（阳明经受邪所致的病证），然而太阳病、阳明病的头痛不至于像被劈开一样剧烈，而疫病则头痛如劈，沉重得无法抬起头部。伤寒病无汗，而疫病则是下半身无汗，上半身有汗，尤其是头部出汗更盛。头是诸阳经汇聚之首，火性炎上，毒火盘踞在体内，五脏之液受其煎熬，热气向上蒸腾，如同笼子上方熏蒸出的露水，所以只有头部出汗特别多。这又是疼痛症状虽然相同，但出汗情况唯独不同的地方。有的表现类似少阳病（少阳经受邪所致的病证）的呕吐，有的表现类似太阴病（太阴脾经受邪所致的病证）的自发性腹泻。少阳病呕吐时，胁部必定疼痛，耳朵必定耳聋；疫病的呕吐，胁部不痛，耳朵不聋，这是因为体内有潜伏的毒邪，邪火侵犯胃腑，毒气上冲，频频发作。太阴病自发性腹泻时，腹部必定胀满；疫病的自发性腹泻，腹部不胀满。大肠是传导排泄的器官，热邪注入大肠，有的排出恶臭污垢，有的旁流清水，有的一天几十次。这又是症状不同但病变部位相同的地方。种种区别都在于此是疫病，为什么还要固执地用治疗伤寒的方法来治疗呢？
张仲景论述冬至后发生的为正伤寒，可见如果不是冬至后发生的，不过是可以类推其治疗方法罢了！他所说的伤寒重在“冬至后”这三个字。世人讨论张仲景的著作，用心研究七十二种病症，至于“冬至后”这三个字，完全不加体会，因此无论春、夏、秋、冬，都用治疗伤寒的方法来处理。总之四季的气候，寒冷只是其中一种。因为冬季因寒冷而致病，所以叫伤寒。到了春季和夏季，由温到热，也叫做伤寒，却不知道寒是从哪里受的伤？我常论述热疫不是伤寒，伤寒不会发斑疹。有人问我说：你说热疫不是伤寒，这已经明白了！至于说伤寒不发斑疹，古人为什么说伤寒热邪未进入胃腑，如果过早使用下法，热邪乘虚进入胃腑，所以发斑；热邪已经进入胃腑，如果不立即使用下法，热邪不得宣泄，也会发斑。这是什么意思呢？我说：这是古人立论的错误。就拿“热”这个字来证明它不是伤寒，热与寒是相反且不相容的。既然说是伤寒，怎么会有热邪进入胃腑？又说热邪已经进入胃腑，为什么还叫伤寒？即使使用白虎汤（清气分实热的代表方剂）、三黄汤（清热泻火的方剂）、化斑汤（清热凉血解毒的方剂）、解毒汤等方剂，都是从热证治疗，没有当作寒证医治，为什么现在的人不能领悟古人的错误，反而因此自己误人又误导他人呢？至于论述大的是斑，小的是疹，红色的表示胃热极盛，十死一生，紫黑色的表示胃烂，九死一生，我判断生死，则又不在于斑的大小、颜色紫黑与否，总是以形态是松浮还是紧束为依据。如果斑一出，松软活泼浮于皮面，红得像朱砂点纸，黑得像墨涂肤，这是毒邪松软活泼外现的表现，即使紫黑成片也可以生还；一出虽小如粟米，紧束有根，像鞋底穿透针，像箭射中靶心，这是毒邪有根锢结的表现，即使不紫黑也会死亡，如果能细心审察衡量，在松浮紧束之间运用神明般的判断力，在临症之时决断生死，才会相信我的话是不谬误的。
At the onset of Shanghan (Cold Damage), fever appears first, followed by aversion to cold; at the onset of Yi (Epidemic Disease), aversion to cold appears first, followed by fever. After one or two days, there is only fever without aversion to cold. This indicates that while the symptoms of fever and aversion to cold are the same, their sequence of appearance differs. Some cases resemble Taiyang disease (disease pattern caused by pathogenic factors invading the Taiyang channel) and Yangming disease (disease pattern caused by pathogenic factors invading the Yangming channel); however, in Taiyang and Yangming diseases, headache does not feel as severe as being split open, whereas in Yi disease, the headache feels like splitting, and the head is so heavy it cannot be lifted. Shanghan presents with no sweating, whereas Yi presents with no sweating on the lower body but sweating on the upper body, with sweating on the head being particularly profuse. The head is the meeting point of all Yang channels; fire has a nature of flaming upward. When toxic heat stagnates internally, it boils the fluids of the five zang organs, causing hot qi to rise upward, similar to dew condensing from steaming under a cover. Thus, sweating is concentrated solely on the head. This further illustrates that although the pain is similar, the sweating pattern is uniquely different. Some cases resemble Shaoyang disease (disease pattern caused by pathogenic factors invading the Shaoyang channel) with vomiting, and some resemble Taiyin disease (disease pattern caused by pathogenic factors invading the Taiyin channel) with spontaneous diarrhea. In Shaoyang vomiting, the hypochondrium must be painful, and the ears must be deaf; in Yi vomiting, the hypochondrium is not painful, and the ears are not deaf, because latent toxins within the body cause evil fire to harass the Stomach, with toxic vapors rushing upward, causing frequent episodes. In Taiyin spontaneous diarrhea, the abdomen must be full; in Yi spontaneous diarrhea, the abdomen is not full. The Large Intestine is the official responsible for transmission and excretion. When heat pours into the Large Intestine, some patients pass foul-smelling feces, some have clear liquid flowing out alongside normal stool, and some defecate dozens of times a day. This again shows that while the symptoms differ, the underlying pathology is the same. Such distinctions clarify that this is Yi disease; why persist in treating it using methods for Shanghan?
Zhang Zhongjing discussed that Zheng Shanghan (True Cold Damage) occurs after the Winter Solstice. This implies that if it does not occur after the Winter Solstice, its treatment can only be inferred by analogy. His emphasis on Shanghan lies in the three characters "after the Winter Solstice." Scholars discussing Zhang Zhongjing's works focus intently on the seventy-two syndromes but completely neglect the significance of "after the Winter Solstice." Consequently, regardless of whether it is Spring, Summer, Autumn, or Winter, they treat all conditions as Shanghan. In essence, among the Qi of the four seasons, cold is merely one type. Because illness contracted in winter is due to cold, it is called Shanghan. However, when it becomes warm in spring and hot in summer, it is still incorrectly termed Shanghan, ignoring where the cold injury originated. I often argue that Re Yi (Heat Epidemic) is not Shanghan, and Shanghan does not manifest with macules and papules. Someone asked me: "You state that Re Yi is not Shanghan, which I understand. But you say Shanghan does not develop macules and papules. Why did the ancients say that if heat in Shanghan has not yet entered the Stomach, premature purgation allows heat to enter the empty Stomach, causing macules; and if heat has already entered the Stomach but purgation is delayed, preventing heat release, macules also appear? What does this mean?" I replied: "This is an error in the ancients' reasoning. Take the character 'heat' itself to prove it is not Shanghan; heat and cold are opposites and do not coexist. If it is Shanghan, how can heat enter the Stomach? If heat has entered the Stomach, why is it still called Shanghan? Even when using formulas such as Baihu Tang (White Tiger Decoction), Sanhuang Tang (Three Yellows Decoction), Huaban Tang (Macule-Transforming Decoction), and Jiedu Tang (Detoxification Decoction), all treatments address heat, never cold. Why do modern practitioners fail to realize the ancients' error, thereby misleading themselves and others? Regarding the distinction between macules and papules: large lesions are macules, small ones are papules. Red color indicates extreme Stomach heat, with a prognosis of ten deaths to one survival; purple-black color indicates rotting of the Stomach, with nine deaths to one survival. However, my judgment of life and death does not depend on the size or purple-black color of the lesions, but solely on whether their morphology is loose and floating or tight and bound. If macules appear loose, lively, and floating on the skin surface, red like cinnabar dots on paper or black like ink on skin, this indicates toxic heat manifesting loosely outwardly; even if purple-black and confluent, survival is possible. If lesions appear small like millet grains but are tight, bound, and rooted, like a needle penetrating the sole of a shoe or an arrow hitting the target, this indicates toxic heat deeply rooted and knotted; even if not purple-black, death is inevitable. If one can carefully examine and weigh these signs, applying divine discernment between loose-floating and tight-bound states, and deciding life and death at the moment of clinical presentation, one will believe my words are not erroneous."