《内经》论伤寒而反发热者有三义∶有当时急发者，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，曰凡病伤寒而成温者，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。先夏至日为病温，后夏至日为病暑，申明冬不藏精，夏亦病温之故。
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。然表寒虽不得内侵，而虚阳亦不得外散，乃下陷入阴中。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，阳日盛则阴愈虚。若
寒日少而蓄热浅，则阳火应春气而病温；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，必深入脏腑，何以只藏于肌肤？且能藏者不能变，何以时换而变其所藏乎？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，发见其本来之面目也。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。
若夫春夏之温热，由冬时触寒所致者，偏在饱暖淫欲之人，不知
持满，醉以入房，以欲绝其精，以耗散其真，阳强不能密，精失守而阴虚，故遗祸至于春夏也。《内经》论温之
脉症治法甚详，学人多不得其要领，仲景独挈发热而渴、不恶寒为提纲，洞悉温病之底蕴，合《内经》冬不藏精
之旨矣。热病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。此发热而不恶寒，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，孤阳无附，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，即是温势猖獗。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，则热邪因白虎而解，
安保寒邪不因白虎而来乎？是伤者当补，治病必求其本耳。如服柴胡汤已渴者，属阳明也，以法治之。夫柴胡汤
有参、甘、芩、枣，皆生津之品，服已反渴，是微寒之剂，不足以解温邪，少阳相火，直起阳明也。是当用白虎
加人参法。若柴胡加人参法，非其治矣。夫相火寄甲乙之间，故肝胆为发温之源；肠胃为市，故阳明为成温之薮。
阳明始虽恶寒，二日即止，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
阴抑阳，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，
因不藏精者此为自伤，其病重。若再感风土之异气，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》，程郊倩
《热病注》，俱有至理可传，愚不复赘。
《内经》论述伤寒后反而出现发热的情况，主要有三种含义：有当时立即发病的，说“人感受寒邪，就会变成发热病”；有过时（延迟）才发热的，说“冬天感受寒邪，春天必定发生温病”；有随季节变化而改名的，说“凡是患伤寒而演变为温病的，在夏至之前发病的叫温病，在夏至之后发病的叫暑病”。至于那些得温病、暑病后立即发病的情况，无需多论；凡是患伤寒而后演变为温病的，虽然病因源于冬天的伤寒，但根本实则种植于人体内部的郁积之火。《内经》说：“精气封藏得好的人，春天不会得温病。”这明确了冬天感受寒邪、春天必发温病的根源。在夏至前发病叫温病，在夏至后发病叫暑病，这是申明冬天不能封藏精气，夏天也会得温病的原因。
人感受寒邪就会变成发热病，这是常理。但到了春夏季才发病的人，是因为他肾阳有余，喜好房事，不避寒冷，虽然外感寒邪，但体内阳气足以抵御它。只知道身体受寒，而不被寒邪所伤。然而表层的寒邪虽不能内侵，体内的虚阳也不能向外发散，于是向下陷入阴分。所以身体感觉不到热，也不发热，这就是所说的“阳病发展到极点就会下行”。冬季施行闭藏的政令，阳气不急于发散，寒邪停留越久，阳气就隐匿得越深，阳气日渐旺盛则阴气越虚弱。如果受寒日子少且蓄热浅，则阳火顺应春气而发为温病；如果受寒日子多且郁热深，则阴火顺应夏气而发为暑病。这是阴气消退、阳气生长，从内部通达于外部的过程。
王叔和不懂这个道理，认为寒毒潜伏在肌肤中，到春天变为温病，到夏天变为暑病。寒邪伤害体表，遇到热气就会消散，怎么能潜伏呢？假设没有热气来抵御它，寒邪必然深入脏腑，怎么能只潜伏在肌肤呢？况且能潜伏的东西不能变化，为什么随着时间推移而改变它所潜伏的性质呢？他不探究病人自身的内伤，只责怪时令的外感；只知道是伤寒引起的，不追究热邪损伤了根本；妄自猜测寒毒能转变为热，不知道这是内陷的阳邪，显露出它本来的面目罢了。他又说辛苦劳作的人，在春夏季多患温热病，都是因为冬天触犯了寒邪所致，而不是因为时行之气。不知道辛苦劳作的人，筋骨动摇，凡运动都属阳，往往触犯寒邪寒气就散去了，有的因饥寒而生病，有的因劳累过度而发热。所以在春夏之时，辛苦劳作的人，因正气虚弱而感染时行之气的不少。
至于那些春夏季的温热病，由冬天触寒引起的，多见于饱食暖衣、纵欲之人，他们不懂得保持精气充盈，醉酒后行房，以欲望断绝精气，以耗散真元，阳气强盛但不能固密，精气失守而导致阴虚，所以灾祸延及到春夏季。《内经》详细论述了温病的脉象、症状和治法，学习的人大多不得要领，只有张仲景单独提出“发热而渴、不恶寒”作为提纲，透彻洞察了温病的底蕴，契合了《内经》冬天不藏精的宗旨。
热病中，口燥舌干而渴属于少阴病，少阴是封藏的根本，是精气所在之处。少阴的表经名叫太阳，太阳根起于至阴穴，名叫阴中之阳，所以太阳病应当恶寒。这里发热却不恶寒，说明阳中没有阴了。并且随即出现少阴病的口渴，太阳的根本完全暴露了。从这里可以看出，违背冬季养藏之气，则少阴不藏，肾气独沉，孤阳无所依附，从而发为温病。温病的证候和治疗，分散见于六经，请类推之。例如伤寒发热但不渴，服药后感到口渴的，这是伤寒与温病的界限。寒去热退，就是伤寒将要解除的症状；寒去热不退，就是温病发作了。例如服用桂枝汤大汗出后，大烦渴不解，脉象洪大的，就是温势猖獗。使用白虎加人参汤，在清泻火热的时候预先保护元气，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，所形成的温邪，随着大汗而发作，怎么会不虚损呢？假如不加人参，那么热邪虽然因白虎汤而解，怎么保证寒邪不因白虎汤而来呢？这是受伤应当补益，治病必须求其根本的道理。例如服用柴胡汤后感到口渴的，属于阳明病，按法治之。柴胡汤含有人参、甘草、黄芩、大枣，都是生津的药材，服用后反而口渴，说明微寒的药力不足以解除温邪，少阳相火直接起于阳明。这时应当用白虎加人参汤的方法。如果用柴胡加人参汤的方法，就不对了。相火寄居在甲乙之间，所以肝胆是发温的源头；肠胃如集市，所以阳明是形成温病的汇聚地。阳明病开始虽然恶寒，第二天就停止了，如果不恶寒反而恶热，这也是患伤寒而演变为温病的征象之一。至于那些温热病不是由伤寒引起的，只需扶阴抑阳，不必用补中益气的方法了。
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。瘀热在里不得宣泄，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，用大承气汤急下之。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略原则。温病和暑病，偶然感受天气而发病的较轻，因不藏精导致的属于自伤，病情较重。如果再感受风土的不同气候，这三种气结合而成温疫。温热病的危害只限于一人；温疫的传播危害，祸患延及邻里。现在的人不分温热和温疫，统称温病，让人厌恶听闻并忌讳谈论，这是由于言辞损害了义理。吴又可的《温疫论》，程郊倩的《热病注》，都有值得流传的真理性理，我不再赘述。
The *Neijing* discusses three meanings regarding the occurrence of fever in cases of cold damage (Shanghan): there are those who develop it immediately upon contraction, described as "when a person is injured by cold, it becomes a disease of heat"; there are those with delayed onset, described as "if one is injured by cold in winter, one will surely suffer from warm diseases in spring"; and there are those whose names change according to the season, described as "anyone who suffers from cold damage and develops into a warm disease will have a 'warm disease' if it occurs before the Summer Solstice, and a 'summerheat disease' if it occurs after the Summer Solstice." Cases where warm or summerheat diseases manifest immediately need not be discussed. For those who contract cold damage and subsequently develop into warm diseases, although the etiology stems from winter cold damage, the root actually lies in the stagnant fire within the individual. The *Neijing* states: "Those who store their essence well will not suffer from warm diseases in spring." This clarifies the source of why winter cold damage leads to spring warm diseases. The distinction between warm disease before the Summer Solstice and summerheat disease after it elucidates the reason why failure to store essence in winter also leads to warm diseases in summer.
It is a constant that when a person is injured by cold, they develop heat. However, for those who fall ill in spring and summer, it is because they possess excess Kidney Yang, engage in excessive sexual activity, and do not avoid cold. Although externally injured by cold, their internal Yang Qi is sufficient to resist it. They feel cold on the body but are not harmed by the cold pathogen. Yet, because the exterior cold cannot penetrate inward, the deficient Yang cannot dissipate outward, causing it to sink downward into the Yin aspect. Consequently, the body feels neither hot nor does it exhibit fever; this is what is meant by "Yang diseases, when reaching their extreme, move downward." In winter, the command of storage prevails, and Yang does not rapidly emerge; the longer the cold persists, the more hidden the Yang becomes. As Yang grows daily, Yin becomes increasingly deficient. If the days of cold are few and accumulated heat is shallow, Yang Fire responds to Spring Qi and manifests as a warm disease; if the days of cold are many and stagnant heat is deep, Yin Fire responds to Summer Qi and manifests as a summerheat disease. This represents the decline of Yin and growth of Yang, extending from the interior to the exterior.
Wang Shuhe failed to understand 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? If there were no heat to resist it, the cold would surely penetrate deeply into the Zang-Fu organs, so how could it remain only in the skin and muscles? Furthermore, what hides cannot transform; why does its nature change over time? He failed to investigate the patient's self-injury and only blamed external seasonal factors; he recognized the cause of cold damage but did not explore how heat damaged the root; he speculatively proposed that cold toxin transforms into heat, unaware that this is actually internally sinking Yang pathogen revealing its original nature. He further claimed that hard-working individuals often suffer from warm-heat diseases in spring and summer due to winter cold exposure, rather than due to epidemic qi. He did not realize that hard-working individuals move their sinews and bones; all movement generates Yang, so cold encountered during exertion usually dissipates. Some may fall ill due to hunger and cold, or develop fever due to fatigue. Therefore, during spring and summer, many hard-working individuals contract epidemic qi due to deficiency.
As for warm-heat diseases in spring and summer caused by winter cold exposure, these predominantly affect those who are well-fed, warmly clothed, and indulgent in lust. These individuals fail to maintain fullness (of essence), engage in intercourse while drunk, deplete their essence through desire, and dissipate their true Yuan Qi. Their Yang becomes strong but unable to secure itself, leading to loss of essence and Yin deficiency, thus bringing disaster in spring and summer. The *Neijing* details the pulse, symptoms, and treatment of warm diseases, yet scholars often miss the key points. Only Zhang Zhongjing extracted "fever with thirst and aversion to cold absent" as the guiding principle, thoroughly penetrating the essence of warm diseases and aligning with the *Neijing*'s teaching on failing to store essence in winter.
In heat diseases, dry mouth and tongue with thirst belong to Shaoyin disease. Shaoyin is the root of sealing and storing, and the residence of essence. The exterior meridian of Shaoyin is named Taiyang. Taiyang originates at Zhiyin (BL67) and is called "Yin among Yang." Therefore, Taiyang disease should present with aversion to cold. Here, fever without aversion to cold indicates an absence of Yin within Yang. The simultaneous appearance of Shaoyin-type thirst reveals the root of Taiyang completely exposed. From this, we see that violating the Winter storage leads to Shaoyin failing to store, Kidney Qi sinking alone, isolated Yang having no attachment, resulting in warm disease. The syndromes and treatments of warm diseases are scattered across the Six Channels; please infer them accordingly. For instance, in cold damage with fever but no thirst, if thirst develops after taking medicine, this marks the boundary between cold damage and warm disease. If cold leaves and heat subsides, it is the sign of resolving cold damage; if cold leaves but heat persists, warm disease has manifested. For example, after taking Guizhi Tang (Cinnamon Twig Decoction) and sweating profusely, if severe restlessness and unrelenting thirst occur with a flooding pulse, this indicates rampant warm pathogen. Using Baihu Jia Renshen Tang (White Tiger Plus Ginseng Decoction) to protect Yuan Qi while clearing fire is the correct treatment for cold damage evolving into warm disease. Since the invading cold resolves with heavy sweating, and the formed warm pathogen emerges with heavy sweating, deficiency inevitably results. Without adding Renshen (Ginseng Root), although the heat might resolve via Baihu Tang, how can we ensure the cold does not enter due to the cooling nature of Baihu Tang? This illustrates that injury requires tonification, and treating disease must seek its root. If thirst occurs after taking Chaihu Tang, it belongs to Yangming; treat accordingly. Chaihu Tang contains Renshen, Gancao (Licorice Root), Huangqin (Scutellaria Root), and Dazao (Jujube Fruit), all generating fluids. Thirst appearing after intake shows that mild cold herbs are insufficient to resolve warm pathogen, and Shaoyang Ministerial Fire rises directly into Yangming. One should use Baihu Jia Renshen Tang method. Using Chaihu Jia Renshen Tang method would be incorrect. Ministerial Fire resides between Jia and Yi (Liver/Gallbladder), so Liver and Gallbladder are the source of warming; the intestines and stomach are like a market, so Yangming is the gathering place for forming warm disease. Yangming disease may initially show aversion to cold, which stops by the second day; if it becomes aversion to heat instead, this is another sign of cold damage evolving into warm disease. For warm-heat diseases not caused by cold damage, one need only support Yin and suppress Yang, without using Buzhong Yiqi Tang (Tonify the Middle and Augment the Qi Decoction).
Moreover, warm pathogens vary in depth, and treatments vary in intensity. For Yangming disease with floating pulse, fever, thirst for water, and difficult urination, Zhuling Tang (Polyporus Decoction) is indicated. For stasis-heat trapped inside unable to vent, causing jaundice, thirst for water, and difficult urination, Yinchen Tang (Artemisiae Scopariae Decoction) is indicated. For Shaoyin disease lasting two to three days with dry mouth and throat, Dachengqi Tang (Major Order the Qi Decoction) should be used urgently to purge. For Jueyin disease with diarrhea and desire to drink water, Baitouweng Tang (Pulsatillae Decoction) is indicated. These are the general principles of Zhang Zhongjing’s treatment of warm diseases. Warm and summerheat diseases contracted merely from weather changes are mild; those resulting from failing to store essence are self-inflicted and severe. If additionally affected by local climatic anomalies, these three qi combine to form epidemic warm disease (Wenyi). The harm of warm/heat diseases affects only one person; the spread of epidemic warm disease harms neighbors. Today, people do not distinguish between warm-heat and epidemic warm diseases, lumping them all under "warm disease," causing disgust and讳言 (taboo discussion), thereby harming meaning through terminology. Wu Keyi’s *Wenyi Lun* (Treatise on Epidemic Febrile Diseases) and Cheng Jiaoqian’s *Rebing Zhu* (Commentary on Heat Diseases) both contain profound truths worth transmitting; I will not add further remarks.