Library

It is stated that wind, cold, summerheat, dampness, improper diet, and overexertion can all cause diseases. These are referred to as the "Five Pathogens" (Wu Xie). If one is injured by cold in winter, one will inevitably suffer from warm disease (Wen Bing) in spring; if one is injured by wind in spring, one will inevitably suffer from undigested food diarrhea (Sun Xie) in summer; if one is injured by summerheat in summer, one will inevitably suffer from malaria (Nue) in autumn; if one is injured by dampness in autumn, one will inevitably suffer from cough in winter. This reflects the qi of the four seasons. However, although the five pathogens invade differently, they are essentially all external pathogens and generally belong to the same category. Only the severe cold of winter has a particularly virulent toxicity. If a person contracts this pathogen and falls ill during winter, it is formally named Cold Damage (Shang Han).

If the pathogenic toxin hides in the skin and muscles and erupts in spring due to rising temperatures, it is called Warm Disease (Wen Bing). If the pathogen lingers for a long time and erupts in summer due to intense heat, it is called Summerheat Disease (Shu Bing). This corresponds to the saying: "Diseases occurring before the Summer Solstice are called Warm Diseases; those occurring after the Summer Solstice are called Summerheat Diseases."

The sequence of disease transmission first affects the Taiyang Channel (Taiyang Jing). The symptoms include headache, stiffness of the neck and back, and rigidity of the waist and spine, with the pulse at the cun, guan, and chi positions on both wrists being floating (Fu). If the Taiyang channel disease does not resolve, it transmits to the Yangming Channel (Yangming Jing). The symptoms include body heat, eye pain, dry nose, and inability to sleep, with the pulse at the cun, guan, and chi positions being large (Da). If the Yangming channel disease does not resolve, it transmits to the Shaoyang Channel (Shaoyang Jing). The symptoms include pain in the chest and hypochondrium and deafness, with the pulse at the cun, guan, and chi positions being wiry (Xian). If the Shaoyang channel disease does not resolve, the Taiyin Channel (Taiyin Jing) receives it. The symptoms include abdominal fullness and heaviness of the body, with the pulse at the cun, guan, and chi positions being faint (Wei). If the Taiyin channel disease does not resolve, the Shaoyin Channel (Shaoyin Jing) receives it. The symptoms include dry mouth, dry tongue, thirst, or slight aversion to cold on the back, with the pulse at the cun, guan, and chi positions being deep (Chen). If the Shaoyin channel disease does not resolve, the Jueyin Channel (Jueyin Jing) receives it. The symptoms include vexation and fullness, curled tongue, and retraction of the scrotum, with the pulse at the cun, guan, and chi positions being slow (Huan).

The transmission of disease involves only the three yang channels and the three yin channels. If the illness has lasted less than three days, the pathogen is still in the yang channels and has not entered the interior; the disease is in the exterior, and sweating therapy should be used to achieve recovery. If four days have passed, the pathogen has entered the yin channels; the disease is in the interior, and purgative therapy should be used to achieve recovery. This is merely a general rule. In fact, there are cases where the pathogen transmits to several channels in one day, and cases where the pathogen remains in the Taiyang channel for several days. Although yang channel diseases generally require sweating, Yangming channel diseases may instead require purgation; although yin channel diseases generally require purgation, Shaoyin channel diseases may sometimes require warming therapy. This is because people's constitutional endowment varies between deficiency and strength, leading to variations in the speed of transmission. There are also cases where no channel transmission occurs, so one must carefully examine the pulse and symptoms.

For diseases affecting these six channels, the pulses and symptoms of the five pathogens differ. Wind injury invariably presents with aversion to wind and a floating, moderate pulse; cold injury invariably presents with aversion to cold and a floating, tight pulse; summerheat injury presents with a deficient pulse; dampness injury presents with a soggy pulse. A tight and vigorous Renying pulse (carotid artery) indicates cold injury; a tight and vigorous Qikou pulse (radial artery) indicates food stagnation. Diagnosing the five pathogens reveals the root of the disease; diagnosing the six channels reveals the branch manifestations. Some diseases located in the exterior cannot be treated with sweating; some located in the interior cannot be treated with purgation. Excessive sweating leads to dryness and depletion of body fluids, resulting in collapse of yang (Wang Yang). Premature purgation causes the pathogen to disturb the diaphragm, forming a knot-chest syndrome (Jie Xiong). Interference between clear and turbid qi transforms into cholera-like disorder (Huo Luan). Internal stasis of toxic heat transforms into blood stasis (Yu Xue). Jaundice (Huang) may occur due to steaming of damp-heat. Macules (Ban) may appear due to excessive yang toxicity (Yang Du). Individuals with strong yang constitution contracting heat become victims of yang toxicity; individuals with strong yin constitution contracting cold become victims of yin toxicity (Yin Du). Restless worms indicate Huo Huo disease; severely deteriorated conditions indicate Bai He disease. Conditions such as relapse due to exertion (Lao Fu) or sexual transmission post-recovery (Yin Yang Yi) require strict moderation even after recovery. The variations are manifold and cannot be exhaustively listed. One should seek appropriate treatments based on categories, aiming for appropriateness. Only Liang Gan diseases (simultaneous exterior and interior contraction) are difficult to treat because both exterior and interior are affected. Other scenarios, such as yin symptoms resembling yang, yang symptoms resembling yin, yin excess repelling yang, or yang excess repelling yin, require careful discernment by the practitioner.