四序流行，春生夏长，秋收冬藏。故春为风木，秋为燥金，冬为寒水，各司其令。惟夏则暑热湿三气迭乘，合
操其柄，此盖大化循环之运，不期然而然，而亦不得不然也。所谓不期然而然者，何也？天一生水，贞下起
元，由水生木，由木生火，至是而天气下降，地气上腾，大生广生，百物蕃阜，此所谓不期然而然者也。所谓
不得不然者何也？夏为火令，秋为金令，由夏入秋，乃火下起金，不惟不能相生，而反相克，秋令不几于或
息乎！全赖地气上腾，长夏土旺，由火生土，借土生金，此又大化斡旋之妙用，四序方得流行，生克方不颠
倒，所谓不得不然者此也。但暑热之气自上而下，湿气自下而上，人在其中，无时无处不受其熏蒸燔灼，
致病已非一端，又况起居不慎，饮食不节，其受病尚可问乎！《金匮》有痉湿 之训，后贤推而广之，立方
愈多，醇驳互见。盖伤寒有痉病，时邪亦有痉病，而时邪之痉，与伤寒之痉，又复不同。三气之痉，只须究其
致病之由，或由风热，或由暑热，或由湿热，见症治症，直截了当。若牵涉伤寒之痉，较量比例，虽繁称博引，
更令人滋惑矣。且三气为病，非有沉寒痼冷，如冬月伤寒之比，若拘执太阳篇中之痉病，动辄麻黄、桂枝，
何异抱薪救火乎！兹特举症于前，列方于后，以便检阅。
四季气候依次更替流行，春天主生发，夏天主生长，秋天主收敛，冬天主闭藏。因此，春季对应风木之气，秋季对应燥金之气，冬季对应寒水之气，各自掌管其时令的气候特征。只有夏季，暑、热、湿三种邪气交替侵袭，共同主导着这一时期的气候特点，这大概是天地大化循环运行的规律，并非刻意如此却自然如此，同时也是不得不如此的必然结果。
所谓“并非刻意如此却自然如此”，是指什么呢？天一生水，冬至一阳生（贞下起元），由水生木，由木生火，到了夏季，天气下降，地气上升，万物广泛生长，百物繁盛富足，这就是所谓的“不期然而然”。
所谓“不得不如此”又是指什么呢？夏季属火令，秋季属金令，从夏季进入秋季，是火气下行而金气兴起，这不仅不能相生，反而形成相克的关系，那么秋令岂不是快要消亡了吗！全靠地气上升，长夏时节土气旺盛，由火生土，借土生金，这是天地大化运转的奇妙作用，四季才能依次流行，五行生克才不会颠倒混乱，这就是所谓的“不得不然”。
但是，暑热之气从上往下弥漫，湿气从下往上蒸腾，人处在其中，无时无刻不在受到这种熏蒸和灼烧，致病原因已不止一端，更何况如果起居不慎、饮食不节制，那受到的病邪伤害又怎能问得清楚呢！《金匮要略》中有对痉病和湿病的训诫，后世的贤者将其推广扩大，制定的方剂越来越多，其中精华与糟粕混杂可见。
伤寒会有痉病，时行邪气也会有痉病，而时行邪气引起的痉病，与伤寒引起的痉病，又是完全不同的。对于这三种邪气（暑、热、湿）引起的痉病，只需探究其致病的原因，或是由于风热，或是由于暑热，或是由于湿热，针对出现的症状进行治疗，直截了当即可。如果牵涉到伤寒的痉病，进行类比比较，虽然频繁引用经典，只会让人更加困惑。
况且这三种邪气致病，并没有像冬季伤寒那样严重的沉寒痼冷之症，如果拘泥于《伤寒论·太阳篇》中的痉病理论，动不动就使用麻黄汤、桂枝汤，这与抱着柴草去救火有什么区别呢！现在特别在前面列举症状，在后面列出方剂，以便查阅。
The four seasons circulate in sequence: spring generates, summer grows, autumn harvests, and winter stores. Therefore, spring corresponds to Wind-Wood, autumn to Dryness-Metal, and winter to Cold-Water, each governing its respective seasonal command. Only in summer do the three qi of Summerheat (Shu), Heat (Re), and Dampness (Shi) alternate in their invasion, jointly controlling the climate. This is due to the cycle of the Great Transformation, occurring naturally without intent, yet inevitably so.
What is meant by "occurring naturally without intent"? Heaven generates Water first; as Winter ends, the primal Yang arises. From Water comes Wood, from Wood comes Fire. By this stage, Heavenly Qi descends and Earthly Qi ascends, allowing for extensive generation and proliferation, with all things flourishing abundantly. This is what is meant by "occurring naturally without intent."
What is meant by "inevitably so"? Summer is governed by the Fire Command, and Autumn by the Metal Command. Transitioning from Summer to Autumn involves Fire descending and Metal rising. This not only fails to generate but instead creates a restraining relationship. Would not the Autumn Command nearly cease to exist? It relies entirely on the ascent of Earthly Qi and the prosperity of Earth during Late Summer. From Fire comes Earth, and through Earth, Metal is generated. This is the subtle function of the Great Transformation's rotation, allowing the four seasons to circulate in order and preventing the reversal of generating and restraining cycles. This is what is meant by "inevitably so."
However, the qi of Summerheat and Heat descends from above, while Dampness rises from below. Humans situated within this environment are subjected to steaming and scorching at all times and places. The causes of disease are manifold. Furthermore, if one is careless in daily life and irregular in diet, how severe can the resulting illness be? *Jin Gui Yao Lue* (Essential Prescriptions of the Golden Cabinet) contains teachings on Spasm (Jing) and Dampness (Shi). Later scholars expanded upon these, creating numerous prescriptions, among which both effective and ineffective ones are intermingled.
Cold Damage (Shanghan) may involve Spasm, and pathogenic factors of the time (Shi Xie) may also involve Spasm. However, Spasm caused by Shi Xie differs fundamentally from that caused by Shanghan. For spasms caused by the three qi (Summerheat, Heat, Dampness), one need only investigate the etiology—whether due to Wind-Heat, Summerheat-Heat, or Dampness-Heat—and treat the symptoms directly. If one conflates these with Spasm from Shanghan and attempts to draw analogies, frequent citation of classics will only lead to greater confusion.
Moreover, diseases caused by these three qi do not involve the deep cold and entrenched chill comparable to Winter Shanghan. To rigidly adhere to the theory of Spasm in the Taiyang Chapter of *Shanghan Lun*, and routinely employ Mahuang Tang (Ephedra Decoction) or Guizhi Tang (Cinnamon Twig Decoction), is akin to adding fuel to the fire. Here, symptoms are listed first, followed by prescriptions, for ease of reference.