内经论伤寒。而反发热者有三义。有当时即发者。曰人伤于寒。则为病热也。有过时发热者。曰冬伤于寒。春必病
温也。有随时易名者。曰凡病伤寒而成湿者。先夏至日为病温。后夏至日为病暑也。夫病温病暑。当时即病者不必论。
凡病伤寒而成者。其病虽由于冬时之伤寒。而根实种于其人之郁火。内经曰。藏于精者。春不病温。此明冬伤于寒。春
必病温之源。先夏至日为温病。后夏至日为暑病。申明冬不藏精。春必病温之故。夫人伤于寒。则为病热其恒耳。此
至春夏而病者。以其人肾阳有余。好行淫欲。不避寒冷。虽外伤于寒。而阳气足以御之。但知身着寒。而不为寒所病。
然表寒虽不内侵。而虚阳亦不得外散。仍下陷入阴中。故身不知热。而亦不发热。所云阳病者。上行极而下也。冬时行
收藏之令。阳不遽发。寒愈久。则阳愈匿。阳日盛。则阴日虚。若寒日多。而蓄热浅。则阴火应春气而病温。若寒日多
而郁热深。则阴火应夏气而病暑。此阴消阳长。从内而达于外也。叔和不知此义。谓寒毒藏于肌肤。至春变为温病。至
夏变为暑病。夫寒伤于表。得热则散。何以能藏。设无热以御之。必深入腑脏。何以只藏于肌肤。且能藏者不能变。何
以时换其所藏乎。不知原其人之自伤。而但咎其时之外伤。只知伤寒之因。不究热伤其本。妄拟寒毒之能变热。不知内
陷之阳邪。发见其本来面目也。又谓辛苦之人。春夏多温热病者。皆因冬时触寒所致。而非时行之气。不知辛苦之人。
动摇筋骨。凡动则为阳。往往触寒即散。或因饥寒而病者有之。或因劳倦而发热者有之。故春夏之时。辛苦之人。因虚
而感时行之气者不少矣。若夫春夏之湿热。由冬时触寒所致者。偏在饱暖淫欲之人。不知持满醉以入房。以竭其精。以
耗其真。阳强不能密。精失守而阴虚。故移祸至于春夏也。内经论温之脉症治法甚详。学人多不得要领。仲景独挈发
热而渴。不恶寒者为提纲。悉温病之底蕴。合内经冬不藏精之旨矣。热论以口燥舌干而渴属少阴。少阴者封蛰之本。
精之处也。少阴之表。名曰太阳。太阳根起于至阴。名曰阴中之阳。故太阳病。当恶寒。此发热而恶寒者。是阳中无阴
矣。而即见少阴之渴。太阳之根本悉露矣。于此见逆冬气。则少阴不藏。肾气独沉。孤阳无时而发为温病也。温病症治。
散见六经。请类推之。如伤寒发热不渴。服汤已渴者。是伤寒温病之关也。寒去而热罢。即伤寒欲解症。寒去而热不解。
是温病发见矣。如服桂枝汤。大汗出后。大烦渴不解。脉洪大者。即是温势猖狂。用白虎加人参预保元气于清火之时。
是凡病伤寒而成温者之正治法也。因所伤之寒邪随大汗而解。所成之温邪随大汗而发。焉得无虚。设不加参。则热邪从
白虎而解。安保寒邪不从白虎而来乎。是伤者当补。治病必求其本耳。如服柴胡渴已。渴者属阳明者也。以法治之。夫
柴
胡汤有参甘姜枣。皆生津之品。服已反渴。是服寒之剂。不足以解温邪。少阳相火直走阳明也。是当白虎加人参法。若
柴胡加人参之法。非其治矣。夫相火寄甲乙之间。故肝胆为发温之源。腹胃为市。故阳明为成温之薮。阳明始虽恶寒。
二日自止。即不恶寒。而反恶热。此亦病伤寒而成温之一征也。若夫温热不因伤寒而致者。只须扶阴折阳。不必补中益
气矣。且温邪有浅深。治法有轻重。如阳明病。脉浮发热。渴欲饮水。小便不利者。猪苓汤主之。瘀热在里不得越。身体发黄。渴欲饮水。小便不利者。茵陈汤主之。少阴病。得之二三日。口燥咽干者。大承气汤急下之。厥阴病下利欲饮水者。白头翁汤主之。此仲景治温之大略也。夫温与暑。偶感天气而病者轻。因不藏精者。为自伤其病重。若再感方土之异气。此三气相合而成温疫也。温热利害。只在一人。温疫移害。祸延邻里。今人不分温热温疫。浑名温病。令人恶闻而讳言之。因于辞之害义矣。吴又可温疫论。程效倩热病注。俱有至理可传。愚不复赘。余义详见方论。
《内经》论述伤寒，其中提到反而出现发热的情况，有三种含义。一种是发病当时就发热的，说：“人感受寒邪，就会变成热病。”另一种是过一段时间才发热的，说：“冬天感受寒邪，春天必定发生温病。”还有一种是随着季节变化而改名的，说：“凡是患伤寒而演变为湿病的，夏至之前发生的称为温病，夏至之后发生的称为暑病。”对于发病当时就患温病或暑病的情况，这里就不多讨论了。
凡是患伤寒而演变而成的疾病，虽然病因源于冬天的伤寒，但根本其实在于人体内部的郁火。《内经》说：“精气内藏不泄的人，春天就不会得温病。”这明确指出了“冬伤于寒，春必病温”的根源。夏至前发生的叫温病，夏至后发生的叫暑病，这是为了阐明因为冬天没有藏精，所以春天必然生病的原因。
人感受寒邪，通常就会变成热病，这是一般规律。但到了春夏季节才发病的，是因为此人肾阳有余，喜好行房事，不注意避寒。虽然外部受到寒邪侵袭，但体内的阳气足以抵御它，只是觉得身体寒冷，而不被寒邪所伤害。然而，表层的寒邪虽然不能内侵，体内的虚阳也无法向外发散，仍然下陷陷入阴分中。所以身体感觉不到热，也不发热。这就是所说的“阳病者，上行极而下也”。冬季施行收藏的命令，阳气不会突然发动。寒邪停留越久，阳气就越隐蔽；阳气日益旺盛，阴气就日益虚弱。如果受寒日子多，但蓄积的热浅，那么阴火顺应春天的气息而引发温病；如果受寒日子多，且郁结的热深，那么阴火顺应夏天的气息而引发暑病。这是阴气消退、阳气增长，从内部通达于外部的表现。
王叔和不懂得这个道理，认为寒毒潜伏在肌肤中，到了春天变成温病，到了夏天变成暑病。寒邪伤害体表，遇到热就会消散，怎么能潜伏下来呢？假设没有热来抵御它，寒邪必定深入脏腑，怎么能只潜伏在肌肤中呢？况且能潜伏的东西不能改变性质，为什么随着时间推移会改变它所潜伏的性质呢？他不知道这是人体自身的损伤，却只责怪外界时气的伤害；只知道伤寒的成因，不探究热邪损伤根本的问题，胡乱猜测寒毒能转变为热，却不知道这是内陷的阳邪显露了其本来面目。
他又说，辛苦劳作的人在春夏季节多患温热病，都是因为冬天触犯了寒邪所致，而不是因为时行之气。他不知道辛苦劳作的人，筋骨经常运动，凡运动就属阳，往往触犯寒邪后寒邪就散去了。有的因为饥寒而生病，有的因为劳累疲倦而发热。所以在春夏季节，辛苦劳作的人，因为体虚而感染时行之气的情况也不少。至于春夏的湿热，如果是由于冬天触犯寒邪所致，那多见于饱食、安逸、淫欲过度的人。这些人不知道保持精力充盈，醉酒后行房，以耗竭精气，消耗真元，导致阳气强盛但不能固密，精气失守而阴虚，所以灾祸转移到了春夏季节。
《内经》详细论述了温病的脉象、症状和治法，但学习的人往往不得要领。张仲景唯独提出“发热而渴，不恶寒”作为提纲，揭示了温病的底细，符合《内经》关于冬天不藏精的理论。《热论》将口燥舌干而渴归属于少阴经。少阴是经脉封藏的根本，也是精气所在之处。少阴的表经叫做太阳。太阳经根起于至阴穴，被称为阴中之阳。所以太阳病应当恶寒。这里发热而且恶寒，说明阳中有阴不足（即阳中无阴），并且立即出现了少阴经的口渴症状，太阳经的根本问题完全暴露出来了。从这里可以看出，违背了冬季养藏之气，就会导致少阴不藏，肾气独沉，孤阳无处发泄而化为温病。
温病的症状和治疗分散记载在六经之中，请以此类推。例如，伤寒发热但不口渴，服药后感到口渴的，这是伤寒与温病的转折点。如果寒去热退，就是伤寒将要解除的症状；如果寒去但热不退，就是温病发作了。例如服用桂枝汤后，大汗出，大烦渴不解，脉象洪大的，这就是温邪势头猖狂，使用白虎加人参汤在清火的同时预先保护元气，这是凡是患伤寒而演变为温病的正确治法。因为所伤的寒邪随着大汗而解除，所形成的温邪随着大汗而发作，怎么会不虚损呢？如果不加入人参，虽然热邪可以通过白虎汤解除，怎么保证寒邪不会通过白虎汤而来呢？受伤的地方应当补益，治病必须寻求根本。
例如服用小柴胡汤后，口渴已经停止又出现口渴的，这属于阳明经病变。按照法治之。小柴胡汤中含有人参、甘草、生姜、大枣，都是生津液的药物，服用后反而口渴，说明服用寒凉性质的药物不足以解除温邪，少阳相火直接走向阳明经。这时应当采用白虎加人参汤的方法。如果使用柴胡加人参汤的方法，就不合适了。相火寄居在甲乙之间（肝胆），所以肝胆是引发温病的源头；脾胃为市，所以阳明经是形成温病的汇聚地。阳明病开始虽然恶寒，第二天自然停止，即使不恶寒，反而怕热，这也是患伤寒而演变为温病的征象之一。
至于温热病不是由伤寒引起的，只需要扶持阴液、折损阳热，不需要补中益气了。而且温邪有深浅之分，治法有轻重之别。例如阳明病，脉浮发热，想喝水，小便不利的，用猪苓汤主治。瘀热在体内不能发散，身体发黄，想喝水，小便不利的，用茵陈汤主治。少阴病，得病两三天，口燥咽干的，用大承气汤急下治疗。厥阴病下利想喝水的，用白头翁汤主治。这是张仲景治疗温病的大致原则。
温病和暑病，偶然感受天气而生病的较轻；因为不藏精导致的，是自伤其病较重。如果再感受当地不同的异气，这三种气结合就形成了温疫。温热病的危害只限于一个人，温疫的传播危害则祸延邻里。现在的人不分温热和温疫，一概称为温病，让人厌恶听到并忌讳谈论，这是因为言辞的危害损害了义理。吴又可的《温疫论》、程效倩的《热病注》，都有值得流传的真知灼见，我不再赘述。其余的意义详见方论部分。
The *Neijing* (Inner Canon) discusses cold damage, mentioning three meanings for cases where fever occurs instead. One is immediate onset: "When a person is injured by cold, it becomes a disease of heat." Another is delayed onset: "If injured by cold in winter, one will surely suffer from warm disease in spring." The third involves changing names with the seasons: "For those who contract cold damage and develop dampness, if it occurs before the Summer Solstice, it is called warm disease; if after the Summer Solstice, it is called summerheat disease." Cases of warm or summerheat disease occurring immediately upon infection are not discussed here.
For diseases evolving from cold damage, although the cause originates from winter cold, the root actually lies in the person's internal stagnant fire. The *Neijing* states: "Those who store essence [Jing] will not suffer from warm disease in spring." This clarifies the source of "injured by cold in winter, causing warm disease in spring." Warm disease refers to onset before the Summer Solstice, and summerheat disease to onset after it, explaining why failure to store essence in winter leads to illness in spring.
Generally, injury by cold results in heat disease. However, illnesses manifesting in spring and summer occur because the individual has excess Kidney Yang, engages in sexual activity excessively, and fails to avoid cold. Although externally injured by cold, the internal Yang is sufficient to resist it; thus, they feel cold but are not harmed by the cold pathogen. Yet, since the exterior cold cannot penetrate inward, the deficient Yang cannot disperse outward and sinks into the Yin. Consequently, there is no sensation of heat and no fever. This is described as "Yang diseases, when rising to the extreme, descend." In winter, the command of storage prevails, and Yang does not suddenly emerge. The longer the cold persists, the more hidden the Yang becomes; as Yang increases daily, Yin decreases daily. If cold exposure is prolonged but accumulated heat is shallow, the Yin fire responds to Spring Qi and causes warm disease. If cold exposure is prolonged and deep stagnation of heat exists, the Yin fire responds to Summer Qi and causes summerheat disease. This represents the decline of Yin and growth of Yang, extending from the interior to the exterior.
Wang Shuhe misunderstood this principle, claiming that cold toxin hides in the skin and muscles, transforming into warm disease in spring and summerheat disease in summer. Cold injuring the exterior should dissipate with heat; how can it hide? Without heat to resist it, cold would deeply invade the Zang-Fu organs, not just remain in the skin and muscles. Moreover, what hides cannot change its nature; why does it transform over time? He failed to recognize self-injury, blaming only external seasonal factors. He knew the cause of cold damage but ignored the root injury caused by heat. He wrongly speculated that cold toxin transforms into heat, failing to realize that the internally sinking Yang pathogen reveals its true nature.
He also stated that hardworking people often suffer warm-heat diseases in spring and summer due to winter cold exposure, rather than epidemic Qi. He did not understand that hardworking individuals move their bones and sinews; movement generates Yang, so cold encountered during activity usually disperses. Some fall ill due to hunger and cold, others due to fatigue and fever. Thus, in spring and summer, many hardworking people contract epidemic Qi due to deficiency. Regarding damp-heat in spring and summer caused by winter cold, this applies mainly to those who are well-fed, sedentary, and indulgent. They fail to preserve fullness, engage in intercourse while drunk, depleting essence and exhausting true Yuan Qi. Their Yang becomes strong but unconsolidated, leading to loss of essence and Yin deficiency, with disasters manifesting in spring and summer.
The *Neijing* details the pulse, symptoms, and treatments for warm diseases, yet students often miss the key points. Zhang Zhongjing uniquely extracted "fever with thirst and aversion to cold absent" as the guiding principle, revealing the essence of warm disease and aligning with the *Neijing*'s teaching on failing to store essence in winter. The *Treatise on Cold Damage* attributes dry mouth and tongue with thirst to the Shaoyin channel. Shaoyin is the root of sealing and storing, the residence of essence. Its exterior counterpart is Taiyang. Taiyang originates at Yongquan (KI1), known as Yang within Yin. Therefore, Taiyang disease typically presents with aversion to cold. Fever with aversion to cold here indicates a lack of Yin within Yang (Yang without Yin), accompanied by Shaoyin-type thirst, exposing the fundamental disorder of Taiyang. This shows that violating winter storage leads to Shaoyin failing to store, Kidney Qi sinking alone, and isolated Yang erupting as warm disease.
Symptoms and treatments of warm diseases are scattered across the Six Channels; please infer accordingly. For instance, cold damage with fever but no thirst, followed by thirst after medication, marks the transition between cold damage and warm disease. If cold leaves and heat subsides, it is the resolution of cold damage. If cold leaves but heat persists, warm disease has manifested. For example, after taking Guizhi Tang (Cinnamon Twig Decoction), profuse sweating leads to severe restlessness, unrelenting thirst, and a flooding pulse. This indicates rampant warm pathogens. Using Baihu Jia Renshen Tang (White Tiger Plus Ginseng Decoction) protects primordial Qi while clearing fire, which is the correct treatment for cold damage evolving into warm disease. The cold pathogen resolves with sweat, but the generated warm pathogen emerges with sweat, causing deficiency. Without Ginseng, although heat clears via White Tiger, how can we ensure cold does not enter? Injury requires tonification; treating disease must address the root.
If, after taking Chaihu Tang (Bupleurum Decoction), thirst ceases then returns, it belongs to the Yangming channel. Treat accordingly. Chaihu Tang contains Renshen (Ginseng Root), Gancao (Licorice Root), Shengjiang (Fresh Ginger), and Dazao (Jujube Fruit), all generating fluids. Returning thirst after taking this cold-natured formula indicates insufficient power to resolve warm pathogens, as Shaoyang Ministerial Fire moves directly to Yangming. Baihu Jia Renshen Tang is indicated; using Chaihu Jia Renshen Tang is inappropriate. Ministerial Fire resides between Jia and Yi (Liver/Gallbladder), making Liver and Gallbladder the source of warm disease. Spleen and Stomach are the market, making Yangming the gathering place of warm disease. Yangming disease may initially have aversion to cold, which stops by day two. Even without aversion to cold, aversion to heat appears, another sign of cold damage evolving into warm disease.
For warm-heat diseases not caused by cold damage, merely support Yin and subdue Yang; middle-tonifying and Qi-supplementing methods are unnecessary. Warm pathogens vary in depth, requiring graded treatments. For Yangming disease with floating pulse, fever, thirst for water, and difficult urination, Zhu Ling Tang (Polyporus Decoction) is primary. For stasis-heat trapped inside causing jaundice, thirst for water, and difficult urination, Yinchen Tang (Artemisia Capillaris Decoction) is primary. For Shaoyin disease presenting with dry mouth and throat within two to three days, Dachengqi Tang (Major Order the Qi Decoction) is used for urgent purgation. For Jueyin disease with diarrhea and desire for water, Baitouweng Tang (Pulsatilla Decoction) is primary. These are Zhang Zhongjing’s general principles for treating warm diseases.
Warm and summerheat diseases contracted incidentally from weather are mild; those due to failing to store essence are severe self-injury. If combined with local abnormal Qi, these three factors create epidemic warm disease. The harm of warm/heat diseases affects an individual; epidemic warm diseases spread to neighbors. Modern people confuse warm/heat with epidemic warm disease, labeling all as "warm disease," causing aversion and silence, harming meaning through terminology. Wu Keyi’s *Treatise on Epidemic Warmth* and Cheng Xiaoqian’s *Annotations on Heat Diseases* contain profound truths worth transmitting; I add nothing further. Remaining details are in the formula discussions.