Warm diseases, whether occurring in the Zang organs or Fu organs, always manifest as internal heat. In contrast, Cold Damage (Shanghan) and Wind Strike (Zhongfeng) originally lack internal heat. When the Zang and Fu organs are harmonious, with no bias towards cold or heat, and the Ying (Nutritive) and Wei (Defensive) Qi do not sink inward, the pathogenic factors of the Six Channels will naturally resolve through sweating once their transmission cycle is complete.

If Yang Qi is excessive, Fu-organ heat arises internally, leading to fever without chills from that point on. If Yin Qi is excessive, Zang-organ cold arises internally, leading to chills without fever from that point on. Once pathogens enter the Fu or Zang organs, the Ying and Wei Qi sink inward, hiding the mechanism of death, and the timing for resolution becomes unpredictable. If Yang is excessive with Fu-organ heat, the prognosis is auspicious; deaths in such cases result from Yang hyperactivity failing to be treated with purgation. If Yin is excessive with Zang-organ cold, the prognosis is ominous; survival in such cases results from Yin receding and the use of warming methods. The principle that Yang generates life while Yin leads to death is evident. Yet, incompetent physicians of later generations employed nourishing Yin to attack Yang, and draining fire to deplete Water (Kidney essence/Yang). Upon encountering Cold Damage, they were preoccupied with the notion that "Cold Damage transmits into heat," blocking their minds. Consequently, they failed to understand the Yin-Yang nature of symptoms and pulses even slightly, causing patients to die due to inappropriate medication, resulting in many wrongful deaths.

The Liver governs Ying Blood, and the Lungs govern Wei Qi. Ying Qi circulates within the vessels, while Wei Qi circulates outside the vessels, yet both are commanded by the Taiyang (Greater Yang) channel. This is because the Taiyang channel is at the exterior of the Six Channels and governs the skin and hair of the entire body. Wind pathogens injure Wei Qi. Wei Qi inherits the Qi of Lung Metal, possessing a nature of clear descent and convergence. When affected by the dispersing action of wind pathogens, Wei Qi converges excessively, causing Ying Qi to stagnate and generate fever. Individuals whose interior Yang is inherently robust often transmit to the Yangming (Yang Brightness) Fu organs, as interior Yang must be robust to enter the Fu organs. Cold pathogens injure Ying Qi. Ying Qi inherits the Qi of Liver Wood, possessing a nature of warm ascent and dispersion. When constrained by the binding action of cold pathogens, Ying Blood becomes increasingly stagnant, causing Wei Qi to stagnate and generate aversion to cold. Individuals whose interior Yin is inherently robust often transmit to the Taiyin (Lesser Yin) Zang organs, as interior Yin must be robust to enter the Zang organs. When Yin and Yang are balanced, pathogens do not enter the Zang or Fu organs, and there is no pathway for Ying and Wei Qi to sink inward; thus, upon the completion of the meridian cycle, resolution occurs through sweating. Taiyin governs Ying, and Yangming governs Wei. Spleen is the root of blood generation, and Stomach is the source of Qi transformation. Ying Blood does not sink because Taiyin Qi is robust; Wei Qi does not sink because Yangming Qi is robust. If Taiyin is deficient, Fu-heat arises and Ying Qi sinks; if Yangming is deficient, Zang-cold moves and Wei Qi sinks. For sinking Wei Qi, recovery of Yang leads to life, while dominance of Yin leads to death. For sinking Ying Qi, recovery of Yin leads to life, while dominance of Yang leads to death. Within the interplay of Yin and Yang dominance and recovery, life and death hang in the balance, requiring careful observation.

The division of Cold Damage into Six Chapters does not imply that all involve meridian diseases. Diseases of the Six Channels are primarily commanded by the Taiyang channel. For those that have not entered the Zang or Fu organs but remain only in the meridians, although they may transmit through all Six Channels, if they have not yet resolved through sweating, there must be Taiyang exterior syndromes. Given the presence of Taiyang exterior syndromes, regardless of which channel the disease has transmitted to, if it is within six or seven days, Wind Strike syndromes should uniformly use Guizhi Tang (Cinnamon Twig Decoction), and Cold Damage syndromes should uniformly use Mahuang Tang (Ephedra Decoction). These are meridian diseases of Taiyang, which actually command the meridian diseases of all Six Channels, so there is no need to establish separate treatment principles for each of the Six Channels. Exceptions exist only when Yang excess leads to Yin depletion entering the Yangming Fu organs, or Yin excess leads to Yang depletion entering the Taiyin Zang organs. When interior syndromes of other channels have formed but the exterior pathogen of Taiyang has not yet subsided, this is termed a "corrupted disease" (Huai Bing) in Taiyang, but a "primary disease" in other channels. Therefore, a section for corrupted diseases is established under Taiyang, and chapters for other channels are set up outside of Taiyang. The Yangming chapter entirely discusses Fu-organ diseases. The Yangming meridian disease, such as the Gegen Tang (Kudzu Decoction) syndrome, involves Fu-organ pathology extending to the meridian, not merely meridian pathology. If it refers to Guizhi Tang or Mahuang Tang syndromes, these are conditions commanded by Taiyang, reiterated here in the Yangming chapter. The Three Yin chapters entirely discuss Zang-organ diseases. The Guizhi Tang syndrome in Taiyin, the Mahuang Xixin Fuzi Tang (Ephedra, Asarum, and Aconite Decoction) syndrome in Shaoyin, and the Mahuang Shengma Tang (Ephedra and Cimicifuga Decoction) syndrome in Jueyin are all Zang-organ pathologies extending to the meridians, not merely meridian pathologies. The Shaoyang (Lesser Yang) chapter discusses half Zang diseases and half Fu diseases. Shaoyang resides in the semi-exterior semi-interior region, serving as the pivot of exterior and interior, and the gateway of Yin and Yang. Yang excess leads to entry into the Fu organs, while Yin excess leads to entry into the Zang organs. The Shaoyang meridian disease, such as the Xiaochaihu Tang (Minor Bupleurum Decoction) syndrome, involves Zang and Fu pathologies extending to the meridian, not merely meridian pathology. Generally, chest and hypochondriac fullness and hardness are syndromes present in both Yangming and Taiyang. This arises because Zang-Fu distension and obstruction block the descending pathway of the Gallbladder meridian, causing meridian and Fu organ stagnation and pressure, resulting in heart and hypochondriac fullness. The alternating chills and fever, along with vomiting and diarrhea, vary: more chills indicate Taiyin disease, more heat indicates Yangming disease, more vomiting indicates Yangming disease, and more diarrhea indicates Taiyin disease. If the condition remains solely in the Shaoyang meridian without connecting internally to the Zang and Fu organs, it will not be as severe as the various Xiaochaihu Tang syndromes. If it refers to the Mahuang Tang syndrome, this is a condition commanded by Taiyang, reiterated here in the Shaoyang chapter.