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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.