世间之病，人皆曰伤寒最难，而非难也，难莫难于六气之相杂而互至耳。六气者，风、
寒、暑、湿、燥、火是也。然冬月致病只三字，风、寒、火是也。春兼四字，风、寒、湿、
火是也。夏兼五字，风、寒、暑、湿、火是也。秋只四字，风、寒、燥、火是也。其有非
时之燥湿，则又天之变气也。大抵气愈杂则其治愈难，吾姑即夏间之五气而明辨之。五气既
明，则其少者不烦言而已解。假如脉浮缓，自汗头痛，发热而恶风者，伤风也；脉浮紧，无
汗头痛，发热而恶寒者，伤寒也。此随时感冒，虽在暑月，亦必有之。亦有纳凉饮冷，脏受
寒侵，遂至呕吐痛泻，脉沉迟，手足厥冷，口鼻气冷，此乃夏月中寒之候，反因避暑太过而
得之也。至于暑症，乃夏月之正病，然有伤暑、中暑、闭暑之殊。伤暑者，病之轻者也，
其症汗出、身热而口渴也；中暑者，病之重者也，其症汗大泄，昏闷不醒，蒸热齿燥，或烦心
喘喝、妄言也；闭暑者，内伏暑气，而外为风寒闭之也，其头痛身痛，发热恶寒者，风寒也
口渴烦心者，暑也。其有霍乱吐泻而转筋者，则又因暑而停食、伏饮以致之也。然停食、
伏饮，湿气也，或身重体痛，腹满胀闷，泄利无度，皆湿也。风寒暑湿，四气动而火随之，
是为五气，所谓夏兼五字者以此。然而各字分见，其为治也易，五字互见，其为治也难。假
如风暑相搏，名曰暑风，其症多发搐搦。暑湿相搏，名曰湿温，其症头痛自汗，谵语，身重
腹满，足胫寒。风热相搏，名曰风温，其症自汗身重，多眠，鼻息鼾，语言难出。湿气兼
风，名曰风湿，湿气兼寒，名曰寒湿，其症骨节烦疼，不能自转侧。复有风寒挟湿，发为刚
、柔二痉，其症口噤，身反张。更有湿热相攻，发为五痿，其症四肢痿废，不能自收持。此
皆五气相兼而互见者也。又况冬月伤寒，伏藏于筋骨之间，至夏感热气而发者，名曰热病。
天行不正之气，发作非时者，名曰疫气。更有病气相传染，沿门合境皆病者，斯为在人之疫
为害尤多。夫此热病、疫病，传之脏腑，大便不通，则燥气随之，是五气之中，复兼六气
矣。更有体虚、劳倦、注夏等病，纷纭交错于其间，若不明辨亲切，孟浪投剂，伤生非浅。
奈何医者一见发热，不问是暑、是湿，概行表散，散之不效，随用和解，解之不去，随用清
凉，凉之不效，继以补益，其中有幸全者，则引为己功，而倾危乍至，则委之天数。岂知致
病之初，认证投药，取效甚易，及其日久病深，败证悉具，虽有善者，亦莫如之何也已！予
不自揣，特着此论，先指夏间五气而发明之，庶纷纭错杂之症，不至混淆，则触目洞然，施治
如法，亦救世之一端耳。嗟乎！五气既明，多者已辨，则三气、四气之杂至者，不难辨矣。
况伤寒一症，表里可分，传中可别，上、中、下三焦可凭，而又何难乎？我故曰∶伤寒非难
而难于六气之相杂而互至也。
世间的疾病，人们都说伤寒最难治，其实并不难；真正难的是六气相互混杂、交替侵袭。所谓六气，就是风、寒、暑、湿、燥、火。然而冬季致病的原因只有三个字：风、寒、火。春季兼有四个字：风、寒、湿、火。夏季兼有五个字：风、寒、暑、湿、火。秋季只有四个字：风、寒、燥、火。如果有非时节的燥或湿，那是天气的异常变化。大致来说，气机越混杂，治疗就越困难。我暂且以夏季的五种气来加以明确辨析。五种气既然明了，那么较少混杂的情况就不必多言也能理解。
假如脉象浮缓，自汗出，头痛，发热且怕风，这是伤风（风邪袭表）；脉象浮紧，无汗，头痛，发热且怕冷，这是伤寒（寒邪袭表）。这些是随季节变化的感冒，即使在暑月也必然存在。也有因为乘凉饮冷，脏腑受寒邪侵袭，导致呕吐、腹痛泄泻，脉象沉迟，手足厥冷，口鼻气息寒冷，这是夏季中寒的表现，反而是因为避暑过度而得的病。至于暑症，是夏季的正病，但有伤暑、中暑、闭暑的区别。伤暑，是病情较轻的，症状是出汗、身热且口渴；中暑，是病情较重的，症状是大汗淋漓，神志昏闷不醒，体内蒸热牙齿干燥，或者心烦气喘、胡言乱语；闭暑，是体内伏藏暑气，而外部被风寒闭塞所致，其头痛身痛、发热恶寒的症状属于风寒，口渴心烦的症状属于暑邪。如果有霍乱吐泻并伴有转筋（肌肉痉挛），则是因暑天饮食停滞、水饮内伏导致的。然而饮食停滞和水饮内伏，属于湿气；如果身体沉重疼痛，腹部胀满闷塞，泄泻无度，也都属于湿邪。风、寒、暑、湿四气发动，火气随之而来，这就构成了五气，这就是所说的“夏季兼有五字”的原因。
然而，各气单独出现时，治疗比较容易；五气互相夹杂出现时，治疗就比较困难。假如风与暑相搏结，名叫暑风，其症状多发抽搐。暑与湿相搏结，名叫湿温，其症状是头痛自汗，说胡话，身体沉重，腹部胀满，小腿发冷。风与热相搏结，名叫风温，其症状是自汗身体沉重，嗜睡，呼吸鼾声，语言难以说出。湿气兼夹风邪，名叫风湿；湿气兼夹寒邪，名叫寒湿，其症状是骨节烦痛，不能自行翻身转动。又有风寒挟带湿气，引发刚痉和柔痉两种病症，其症状是牙关紧闭，身体向后反张。更有湿热相互攻冲，引发五种痿证，其症状是四肢痿废，不能自主收持。这些都是五气相兼而同时出现的病症。
况且冬季感受伤寒，邪气潜伏在筋骨之间，到了夏季感受热气而发作的，名叫热病。天时不正之气，在非时节发作的，名叫疫气。更有病气相互传染，沿着门户、整个区域都发病的，这就是由人引起的疫病，危害尤其严重。这种热病、疫病，传入脏腑，导致大便不通，那么燥气就随之而来，这是在五气之中，又兼杂了第六气（燥）。更有体质虚弱、劳倦过度、注夏（季节性倦怠）等疾病，纷繁交错在其中，如果不仔细辨别，鲁莽用药，伤害生命非常深重。
可惜医生们一见发热，不问是暑邪还是湿邪，一概使用发散解表的方法，发散无效后，随即使用和解的方法，和解不去除病邪，随即使用清凉的方法，清凉无效后，继之以补益。其中有侥幸痊愈的，就归功于自己；一旦病情危重，就推卸给天命。哪里知道致病之初，正确辨证投药，取效非常容易；等到日久病深，败证全部具备，即使有高明的人，也无能为力了！我自不量力，特意撰写这篇论述，先指出夏季的五种气加以阐明，希望那些纷繁错杂的病症不至于混淆，从而能够触目了然，施治合乎法度，这也是救世的一个方面罢了。唉！五种气既然明了，较多的已能辨别，那么三种、四种气混杂而至的情况，不难辨别了。何况伤寒一症，表里可以区分，传变与直中可以辨别，上、中、下三焦可以凭据，又有什么难的？所以我说道：伤寒并不难，难的是六气相互混杂、交替侵袭啊。
Diseases in the world are often said by people to be most difficult when they are Cold Damage (Shanghan, 伤寒), but this is not actually difficult. The greatest difficulty lies in the intermingling and mutual arrival of the Six Qi (Six Pathogenic Factors: Wind, Cold, Summer-heat, Dampness, Dryness, Fire). The Six Qi refer to Wind (Feng), Cold (Han), Summer-heat (Shu), Dampness (Shi), Dryness (Zao), and Fire (Huo). However, in winter, the pathogenic factors involve only three characters: Wind, Cold, and Fire. In spring, there are four: Wind, Cold, Dampness, and Fire. In summer, there are five: Wind, Cold, Summer-heat, Dampness, and Fire. In autumn, there are four: Wind, Cold, Dryness, and Fire. If there is Dryness or Dampness out of season, these are abnormal changes of heavenly Qi. Generally speaking, the more mixed the Qi, the more difficult the treatment. I will briefly clarify the Five Qi of summer to illustrate this point. Once the Five Qi are clear, the cases involving fewer factors can be understood without further explanation.
For instance, if the pulse is floating and slow, with spontaneous sweating, headache, fever, and aversion to wind, this is Wind Injury (Shangfeng, 伤风). If the pulse is floating and tight, with no sweating, headache, fever, and aversion to cold, this is Cold Damage (Shanghan, 伤寒). These are seasonal common colds, which inevitably occur even in the summer months. There are also cases where one seeks coolness and drinks cold substances, causing the internal organs to be invaded by Cold, leading to vomiting, abdominal pain, and diarrhea. The pulse is deep and slow, the hands and feet are cold, and the breath from the mouth and nose is cold. This is a presentation of Cold Strike (Zhonghan, 中寒) in summer, ironically caused by excessive avoidance of heat. As for Summer-heat Syndrome (Shuzheng, 暑症), it is the proper disease of summer, but it differs into Mild Summer-heat Injury (Shangshu, 伤暑), Severe Summer-heat Stroke (Zhongshu, 中暑), and Closed Summer-heat (Bishu, 闭暑). Mild Summer-heat Injury is the lighter condition, characterized by sweating, body heat, and thirst. Severe Summer-heat Stroke is the heavier condition, characterized by profuse sweating, unconsciousness and confusion, internal steaming heat, dry teeth, or irritability, panting, and delirious speech. Closed Summer-heat involves latent Summer-heat Qi internally, blocked externally by Wind and Cold. The symptoms of headache, body pain, fever, and aversion to cold belong to Wind and Cold; the symptoms of thirst and irritability belong to Summer-heat. If there is Cholera-like vomiting and diarrhea accompanied by muscle cramps (Zhuanjin, 转筋), this is caused by food stagnation and retained fluids due to Summer-heat. However, food stagnation and retained fluids constitute Dampness. Symptoms such as heavy body and pain, abdominal fullness and oppression, and uncontrolled diarrhea all belong to Dampness. When Wind, Cold, Summer-heat, and Dampness move, Fire follows them, constituting the Five Qi. This is what is meant by "summer involves five characters."
However, when each factor appears separately, treatment is easy; when all five factors intermingle, treatment is difficult. For example, when Wind and Summer-heat struggle together, it is named Summer-heat Wind (Shufeng, 暑风), characterized by frequent convulsions. When Summer-heat and Dampness struggle together, it is named Damp-Warmth (Shiwēn, 湿温), characterized by headache, spontaneous sweating, delirium, heavy body, abdominal fullness, and cold calves. When Wind and Heat struggle together, it is named Wind-Warmth (Fengwēn, 风温), characterized by spontaneous sweating, heavy body, excessive sleepiness, snoring respiration, and difficulty speaking. When Dampness combines with Wind, it is named Wind-Dampness (Fengshi, 风湿); when Dampness combines with Cold, it is named Cold-Dampness (Hanshi, 寒湿), characterized by painful joints and inability to turn over independently. Furthermore, Wind-Cold combined with Dampness can manifest as Gang Spasm (Gangjing, 刚痉) and Rou Spasm (Roujing, 柔痉), characterized by locked jaw and opisthotonos (body arched backward). Additionally, Damp-Heat attacking each other can cause the Five Wasting-Thirst syndromes (Wuwei, 五痿), characterized by flaccid paralysis of the four limbs and inability to grasp or hold objects. All these are cases where the Five Qi combine and appear simultaneously.
Moreover, Cold Damage contracted in winter may lie latent between the sinews and bones, and erupt in summer upon exposure to hot Qi; this is named Hot Disease (Rebing, 热病). Abnormal Qi of heaven that erupts out of season is named Epidemic Qi (Yiqi, 疫气). Even more so, diseases transmitted by pathogenic Qi, spreading through households and entire regions, are human-induced epidemics, which cause even greater harm. When these Hot Diseases and Epidemics transmit to the Zang-Fu organs and cause constipation, Dryness Qi follows, meaning that within the Five Qi, the Sixth Qi (Dryness) is additionally involved. Furthermore, conditions such as deficiency constitution, fatigue, and Xia Fatigue (Zhuxia, 注夏 - seasonal lethargy) are intricately interwoven among them. If one does not distinguish them carefully and prescribes medications rashously, the harm to life is profound.
Alas! Physicians, upon seeing fever, do not ask whether it is Summer-heat or Dampness, but generally apply dispersing and releasing methods. If dispersion fails, they switch to harmonizing methods. If harmonization fails, they switch to cooling methods. If cooling fails, they resort to tonification. Those who luckily recover attribute it to their own merit, while those who suddenly face danger blame it on fate. They do not realize that at the beginning of the disease, correct syndrome differentiation and medication yield quick results. But once the disease has lasted long and become deep, with all signs of collapse present, even skilled physicians cannot help. I, presumptuously, have written this treatise to first elucidate the Five Qi of summer, hoping that complex and mixed syndromes will not be confused, allowing for clear vision and appropriate treatment, which is one way to save the world. Sigh! Once the Five Qi are clear and the more complex ones distinguished, distinguishing the mixture of Three or Four Qi is not difficult. Moreover, regarding Cold Damage, exterior and interior can be distinguished, transmission versus direct attack can be differentiated, and the Upper, Middle, and Lower Jiao (Sanjiao, 三焦) can be assessed. What then is difficult? Therefore, I say: Cold Damage itself is not difficult; the difficulty lies in the intermingling and mutual arrival of the Six Qi.