论曰风寒暑湿，饮食劳倦，皆能为病。是谓五邪。冬伤于寒者。春必病温。春伤于风者，
夏必飧泄，夏伤于暑者，秋必 疟，秋伤于湿者。冬必咳嗽。是乃四时之气也。然五邪所中
虽不同，本皆外邪，大率同类，唯冬时严寒，其毒厉尤甚，人或中之，病在冬时，则正名伤
寒。若邪毒藏于肌肤，至春之时，乘温而发者，为温病。若留连日久，至夏之时，乘盛暑而
发者，为暑病。所谓先夏至日为病温，后夏至日为病暑是也，其病传之次，先客于太阳。其
病令人头项痛，腰脊强，其脉尺寸皆浮，太阳不已。传于阳明，其病体热目疼鼻干，不得卧，
其脉尺寸皆大。阳明不已，传于少阳，其病胸胁痛而耳聋，其脉尺寸皆弦。少阳不已，太阴
受之，其病腹满体重，其脉尺寸俱微。太阴不已，少阴受之，其病口燥舌干而渴，或背微恶
寒。其脉尺寸俱沉，少阴不已，厥阴受之，其病烦满舌卷囊缩。其脉尺寸俱缓，病之所传，
不过三阳三阴而已，其未满三日者。邪在阳经未入于里，其病在表，宜汗之而愈，若经四日
者，邪入阴经，其病在里。宜下之而愈，特其大略尔，盖有一日而传至数经者，亦有数日而
尚在太阳者，阳病虽宜发汗。阳明之病，反宜下之，阴病虽宜下之，少阴之病，或宜温之。
由人之禀受虚盛，其传有迟速，又有不传经者，当审其脉证，凡此六经受病。五邪脉证各不
同，伤风者必恶风，其脉浮缓，伤寒者必恶寒，其脉浮紧，以至伤暑脉虚。伤湿脉濡，人迎
紧盛为伤寒，气口紧盛为伤食，诊得五邪，知其本也。诊得六经，知其标也，有病虽在表而
不可汗者，或在里而不可下者，或若汗之太多，则津液燥竭。遂致亡阳。下之太早，则邪气
动膈，乃成结胸，清浊相干，则变为霍乱，毒热内瘀。则变为瘀血。又或为发黄者。湿热相
蒸也。或为发斑者，阳毒太盛也，阳盛之人，得之于热。乃为阳毒，阴盛之人，得之于寒，
乃为阴毒，虫动则为狐惑，坏病之甚。则为百合，若劳复阴阳易之类，虽瘥后犹宜节慎，变
态多端，不可备举。当以类求之，皆以适当为良，唯二感之病，表里皆受邪为难治，其他或
阴证似阳。阳证似阴，或阴盛隔阳，阳盛隔阴者，在诊病者，以意详之。
论述说：风、寒、暑、湿以及饮食不节和劳倦过度，都能导致疾病。这被称为“五邪”。冬季感受寒邪的，到了春季必定发生温病；春季感受风邪的，到了夏季必定发生完谷不化的泄泻（飧泄）；夏季感受暑邪的，到了秋季必定发生疟疾；秋季感受湿邪的，到了冬季必定发生咳嗽。这是四季气候变化的规律。然而，虽然五邪侵袭人体的途径不同，但本质上都是外感邪气，大体属于同类。只有冬季的严寒，其毒性猛烈尤为严重，人如果中了这种邪气，在冬季发病，就正名为“伤寒”。
如果邪毒潜伏在肌肤之间，到了春季，趁着气温回暖而发作的，称为温病；如果邪气停留时间较长，到了夏季，趁着酷暑而发作的，称为暑病。这就是所谓“夏至日之前发生的病叫温病，夏至日之后发生的病叫暑病”的意思。
疾病的传变次序，首先客居于太阳经。其病症表现为头痛、项强、腰脊僵硬，脉象寸关尺三部皆浮。如果太阳经的病未愈，就会传入阳明经。其病症表现为身体发热、眼睛疼痛、鼻干、无法安卧，脉象寸关尺三部皆大。如果阳明经的病未愈，就会传入少阳经。其病症表现为胸胁部疼痛且耳聋，脉象寸关尺三部皆弦。如果少阳经的病未愈，太阴经受之，其病症表现为腹部胀满、身体沉重，脉象寸关尺三部皆微细。如果太阴经的病未愈，少阴经受之，其病症表现为口燥、舌干而渴，或者背部微微恶寒，脉象寸关尺三部皆沉。如果少阴经的病未愈，厥阴经受之，其病症表现为心烦腹满、舌体卷缩、阴囊收缩，脉象寸关尺三部皆缓。
疾病所传的经络，不过是在三阳经和三阴经之间循环而已。病程未满三日的，邪气还在阳经，未进入体内，病位在表，适宜用发汗法治疗即可痊愈；如果经过四日，邪气进入阴经，病位在里，适宜用攻下法治疗即可痊愈。这只是大概的情况罢了。实际上，也有一天之内就传变到好几条经脉的，也有经过数日邪气还停留在太阳经的。阳经的病虽然适宜发汗，但阳明经的病反而适宜攻下；阴经的病虽然适宜攻下，但少阴经的病，有时适宜用温补法。这是因为人的体质禀赋有虚弱的也有强盛的，所以传变有快有慢。还有不发生传经的情况，应当仔细审查脉象和证候。
凡是这六经受病，五邪的脉象和证候各不相同。伤风的必定怕风，脉象浮而缓；伤寒的必定怕冷，脉象浮而紧；至于伤暑则脉象虚，伤湿则脉象濡软。人迎脉（颈动脉）紧盛为伤寒，气口脉（桡动脉）紧盛为伤食。诊察出五邪，就能知道疾病的本源；诊察出六经，就能知道疾病的标象。有的病虽然在表却不可发汗，有的在里却不可攻下。如果发汗太多，就会导致津液枯竭，进而造成亡阳；如果攻下太早，就会使邪气扰动膈膜，形成结胸证；清浊之气相互干扰，就会变成霍乱；毒热内郁，就会变成瘀血；又或者是发黄，这是由于湿热相蒸所致；又或者是发斑，这是由于阳毒太盛所致。阳气旺盛的人，感受热邪，就成为阳毒；阴气旺盛的人，感受寒邪，就成为阴毒。虫动不安则为狐惑病，病情恶化严重的则为百合病。如果是劳复、阴阳易之类的情况，即使病愈后仍然需要节制谨慎。病变形态多种多样，无法一一列举。应当按类别寻求对应的方法，都以恰当为宜。只有两感病（表里同时受邪），因为表里都受到邪气侵袭，所以难以治疗。其他如阴证似阳、阳证似阴，或者阴盛格阳、阳盛格阴的情况，则需要由诊治疾病的医生用心详细辨别。
It is stated that wind, cold, summerheat, dampness, improper diet, and overexertion can all cause diseases. These are referred to as the "Five Pathogens" (Wu Xie). If one is injured by cold in winter, one will inevitably suffer from warm disease (Wen Bing) in spring; if one is injured by wind in spring, one will inevitably suffer from undigested food diarrhea (Sun Xie) in summer; if one is injured by summerheat in summer, one will inevitably suffer from malaria (Nue) in autumn; if one is injured by dampness in autumn, one will inevitably suffer from cough in winter. This reflects the qi of the four seasons. However, although the five pathogens invade differently, they are essentially all external pathogens and generally belong to the same category. Only the severe cold of winter has a particularly virulent toxicity. If a person contracts this pathogen and falls ill during winter, it is formally named Cold Damage (Shang Han).
If the pathogenic toxin hides in the skin and muscles and erupts in spring due to rising temperatures, it is called Warm Disease (Wen Bing). If the pathogen lingers for a long time and erupts in summer due to intense heat, it is called Summerheat Disease (Shu Bing). This corresponds to the saying: "Diseases occurring before the Summer Solstice are called Warm Diseases; those occurring after the Summer Solstice are called Summerheat Diseases."
The sequence of disease transmission first affects the Taiyang Channel (Taiyang Jing). The symptoms include headache, stiffness of the neck and back, and rigidity of the waist and spine, with the pulse at the cun, guan, and chi positions on both wrists being floating (Fu). If the Taiyang channel disease does not resolve, it transmits to the Yangming Channel (Yangming Jing). The symptoms include body heat, eye pain, dry nose, and inability to sleep, with the pulse at the cun, guan, and chi positions being large (Da). If the Yangming channel disease does not resolve, it transmits to the Shaoyang Channel (Shaoyang Jing). The symptoms include pain in the chest and hypochondrium and deafness, with the pulse at the cun, guan, and chi positions being wiry (Xian). If the Shaoyang channel disease does not resolve, the Taiyin Channel (Taiyin Jing) receives it. The symptoms include abdominal fullness and heaviness of the body, with the pulse at the cun, guan, and chi positions being faint (Wei). If the Taiyin channel disease does not resolve, the Shaoyin Channel (Shaoyin Jing) receives it. The symptoms include dry mouth, dry tongue, thirst, or slight aversion to cold on the back, with the pulse at the cun, guan, and chi positions being deep (Chen). If the Shaoyin channel disease does not resolve, the Jueyin Channel (Jueyin Jing) receives it. The symptoms include vexation and fullness, curled tongue, and retraction of the scrotum, with the pulse at the cun, guan, and chi positions being slow (Huan).
The transmission of disease involves only the three yang channels and the three yin channels. If the illness has lasted less than three days, the pathogen is still in the yang channels and has not entered the interior; the disease is in the exterior, and sweating therapy should be used to achieve recovery. If four days have passed, the pathogen has entered the yin channels; the disease is in the interior, and purgative therapy should be used to achieve recovery. This is merely a general rule. In fact, there are cases where the pathogen transmits to several channels in one day, and cases where the pathogen remains in the Taiyang channel for several days. Although yang channel diseases generally require sweating, Yangming channel diseases may instead require purgation; although yin channel diseases generally require purgation, Shaoyin channel diseases may sometimes require warming therapy. This is because people's constitutional endowment varies between deficiency and strength, leading to variations in the speed of transmission. There are also cases where no channel transmission occurs, so one must carefully examine the pulse and symptoms.
For diseases affecting these six channels, the pulses and symptoms of the five pathogens differ. Wind injury invariably presents with aversion to wind and a floating, moderate pulse; cold injury invariably presents with aversion to cold and a floating, tight pulse; summerheat injury presents with a deficient pulse; dampness injury presents with a soggy pulse. A tight and vigorous Renying pulse (carotid artery) indicates cold injury; a tight and vigorous Qikou pulse (radial artery) indicates food stagnation. Diagnosing the five pathogens reveals the root of the disease; diagnosing the six channels reveals the branch manifestations. Some diseases located in the exterior cannot be treated with sweating; some located in the interior cannot be treated with purgation. Excessive sweating leads to dryness and depletion of body fluids, resulting in collapse of yang (Wang Yang). Premature purgation causes the pathogen to disturb the diaphragm, forming a knot-chest syndrome (Jie Xiong). Interference between clear and turbid qi transforms into cholera-like disorder (Huo Luan). Internal stasis of toxic heat transforms into blood stasis (Yu Xue). Jaundice (Huang) may occur due to steaming of damp-heat. Macules (Ban) may appear due to excessive yang toxicity (Yang Du). Individuals with strong yang constitution contracting heat become victims of yang toxicity; individuals with strong yin constitution contracting cold become victims of yin toxicity (Yin Du). Restless worms indicate Huo Huo disease; severely deteriorated conditions indicate Bai He disease. Conditions such as relapse due to exertion (Lao Fu) or sexual transmission post-recovery (Yin Yang Yi) require strict moderation even after recovery. The variations are manifold and cannot be exhaustively listed. One should seek appropriate treatments based on categories, aiming for appropriateness. Only Liang Gan diseases (simultaneous exterior and interior contraction) are difficult to treat because both exterior and interior are affected. Other scenarios, such as yin symptoms resembling yang, yang symptoms resembling yin, yin excess repelling yang, or yang excess repelling yin, require careful discernment by the practitioner.