《内经》曰∶人之伤于寒也，则为病热。又曰∶热病者，伤寒之类也。此之言热病，乃冬令严寒，人
触冒之，感而即病之谓，而非夏时暑病为热病之比。夏时热病，今夏至后，天令暑热炎蒸之邪，感伤于
人，与冬时伤寒之热病，大不侔也。冬寒之热病，自表而入，夏暑之热病，自内而发。病不同时，故治
法亦异。辛温发表与寒凉清解，有不可同日语矣。自王叔和序《伤寒论》而曰∶中而即病，名曰伤寒，不
即病者，寒毒藏于肌肤，至春变为温病，夏至变为暑病。暑病者，热极重于温也。斯言出，而后世医者，
俱以春时之温病，由冬伤之寒而变；夏月之暑病，亦由冬伤之寒而变。是温病、热病，皆因冬时受寒，而
至春、夏以变焉者也。其言不大谬乎？经云∶冬伤于寒，春必病温者，盖以冬时不藏精，触冒寒邪，则春
时必有温病之症，非以春时之温病，必自冬寒而变也。又云∶夏至后病热为暑。此本天令大热之气，即
时感受而成，岂有寒毒藏于肌肤之中，至春不发，历过春三月，伏藏至夏至后，而又变为热，有是理乎？叔
和又云∶三月、四月，其时阳气尚微，为寒所折，病热则轻；五月、六月，阳气已盛，为寒所折，病热则
重。夫三月、四月、五月、六月之寒，此暴时之寒气也，与冬令严寒伏藏之寒不同。既曰春变为温，夏变
为热，由冬时之寒传变而来，又云阳气已盛，为寒所折，则其变病为温、为热，其冬令之寒乎？抑时行之
寒乎？立言为矛盾矣。夫风寒伤人，未发病已前，不能预知其客于某经络、某脏腑，及其发病已后，而后
能审其为何因何感也。若谓冬时受寒，而必逆决为春之必变为温病也，夏之必变为热病也，则凿而不
可稽矣。大约冬伤于寒而即病者，曰伤寒；冬不藏精而春病者，曰温病；夏伤于暑而病热者，曰热病。此
三证本各以其时受病，而非寒变为温、变为热之谓也。
《黄帝内经》说：人受寒邪侵袭，就会发生热病。又说：热病，属于伤寒的类别。这里所说的热病，是指冬季严寒之时，人们触犯冒犯寒邪，感邪后立即发病的情况，而不是将夏季的暑病等同于热病。夏季的热病，是指出夏至之后，自然界暑热蒸腾的邪气，感伤人体所致，这与冬季因伤寒引起的热病，有着巨大的差别。冬季寒冷引起的热病，病邪从体表侵入；夏季暑热引起的热病，病邪从体内发出来。发病季节不同，所以治疗方法也不同。辛温解表法与寒凉清解法，是完全不可相提并论的。
自从王叔和为《伤寒论》作序后说道：感寒邪后立即发病的，名叫伤寒；没有立即发病的，寒毒潜伏在肌肤之中，到了春季就变为温病，到了夏至就变为暑病。暑病，其热势极重，比温病更严重。这种说法出现后，后世的医生们都认为，春季的温病是由冬季感受寒邪演变而来；夏季的暑病，也是由冬季感受寒邪演变而来。于是认为温病、热病，都是因为冬季受了寒邪，直到春、夏两季才发生变化而产生的。这种说法难道不是大错特错吗？
《内经》说：“冬季感受寒邪，春季必定发生温病”，这大概是因为冬季肾精不藏，又触犯冒犯寒邪，那么到了春季必然会出现温病的症状，并不是说春季的温病一定是由冬季的寒邪演变而来的。又说：“夏至之后发生的发热病症称为暑病”。这本来是自然界大热之气，即时感受而形成的，怎么会有寒毒潜伏在肌肤之中，到了春季不发作，经过整个春季三个月，潜伏到夏至之后，又转变为热病，有这样的道理吗？
王叔和又说：“三月、四月的时候，阳气还微弱，被寒气遏制，发病时热势较轻；五月、六月的时候，阳气已经旺盛，被寒气遏制，发病时热势较重。”三、四、五、六月的寒气，这是当时暴发的寒气，与冬季严寒潜伏收藏的寒气是不同的。既然说是春季变为温病，夏季变为热病，是由冬季的寒邪传变而来，又说阳气旺盛时被寒气遏制，那么由此产生的温病、热病，究竟是源于冬季的寒邪呢，还是源于当时流行的寒邪呢？他的言论自相矛盾了。
风寒伤害人体，在未发病之前，不能预先知道它客居于哪条经络、哪个脏腑，等到发病之后，才能审察它是由于什么原因、什么邪气感伤的。如果说冬季感受寒邪，就必然能逆推断定春季一定变为温病，夏季一定变为热病，那就牵强附会且无法考证了。
大致来说，冬季感受寒邪而立即发病的，叫作伤寒；冬季肾精不藏而在春季发病的，叫作温病；夏季感受暑邪而发病热的，叫作热病。这三种证候本来都是各自在其相应的季节感受病邪而发生的，并不是指寒邪转变为温病、转变为热病的意思。
The *Huangdi Neijing* (Yellow Emperor's Inner Canon) states: "When humans are injured by cold, they develop a heat disease." It also states: "Heat diseases belong to the category of Shanghan (Cold Damage)." The heat disease mentioned here refers to contracting the pathogen immediately upon exposure to severe cold during the winter season, and is not comparable to summerheat diseases occurring in summer. Summerheat diseases arise after the Summer Solstice, when the pathogenic factor of steaming summerheat from the natural environment injures the human body; this is vastly different from the heat disease caused by Cold Damage in winter. Heat diseases caused by winter cold enter from the exterior, whereas heat diseases caused by summer heat originate from within. Since the onset times differ, the treatment methods must also differ. Acrid-warm exterior-releasing methods and cold-cool clearing-and-resolving methods are incomparable.
Since Wang Shuhe wrote the preface to the *Shanghan Lun* (Treatise on Cold Damage), stating: "Those who contract cold and fall ill immediately are named Shanghan; those who do not fall ill immediately harbor the cold toxin in their skin and muscles, which transforms into Wenbing (Warm Diseases) in spring and Shubing (Summerheat Diseases) at the Summer Solstice. Shubing is extremely hot and more severe than Wenbing." With this statement emerging, physicians of later generations all believed that springtime Wenbing arises from winter cold injury, and summertime Shubing also arises from winter cold injury. Thus, it was held that both Wenbing and Rebing (Heat Diseases) result from winter cold exposure, transforming only in spring and summer. Is this statement not greatly erroneous?
The Classic says: "If one is injured by cold in winter, one will surely suffer from Wenbing in spring." This implies that if one fails to store essence during winter and is exposed to cold pathogens, one will inevitably exhibit symptoms of Wenbing in spring; it does not mean that springtime Wenbing necessarily transforms from winter cold. Furthermore, it states: "Heat occurring after the Summer Solstice is called Shu (Summerheat)." This originates from the intense heat qi of the natural environment, contracted immediately upon exposure. How could there be a logic where cold toxin hides in the skin and muscles, does not manifest in spring, lies dormant through the three months of spring, and then transforms into heat after the Summer Solstice? Such reasoning is untenable.
Wang Shuhe further stated: "In the third and fourth lunar months, yang qi is still weak; restrained by cold, the resulting heat illness is mild. In the fifth and sixth lunar months, yang qi is abundant; restrained by cold, the resulting heat illness is severe." The cold in the third, fourth, fifth, and sixth months is sudden seasonal cold, distinct from the severe cold stored away in winter. If it is said that spring transforms into Wenbing and summer transforms into heat due to the transmission of winter cold, yet it is also said that abundant yang qi is restrained by cold, then regarding the transformation into Wenbing or heat, does it stem from winter cold or from seasonal epidemic cold? His statements are contradictory.
When wind-cold injures the human body, before the disease manifests, one cannot predict which meridian or zang-fu organ the pathogen resides in; only after manifestation can one ascertain the cause and nature of the contraction. To claim that winter cold exposure necessitates the prediction that spring will definitely transform into Wenbing and summer into heat is rigid and unverifiable.
Generally speaking, cold damage contracted in winter with immediate onset is called Shanghan; illness arising in spring due to failure to store essence in winter is called Wenbing; heat illness contracted from summerheat in summer is called Rebing. These three conditions each arise from pathogenic factors contracted in their respective seasons, and do not refer to cold transforming into Wenbing or heat.