Library

Plague (Yi Wen) arises when the heat pathogen of Cold Damage (Shang Han) has not yet subsided, and one is further affected by the epidemic qi of the season, resulting in plague. Its symptoms include high fever, headache, irritability with thirst, nausea and vomiting; there may be sweating or no sweating. These are all caused by the combination of warm and heat pathogens. Treatment should primarily focus on cooling and clearing heat. The Classics state: "If one encounters warm qi again, it transforms into plague." This indicates that plague results from a secondary infection of warm qi, and wen du (warm toxin) results from a secondary infection of warm-heat qi. Why does the *Huorensu* confuse this by annotating it under winter-warm syndrome, and why does the *Baibing Ge* forcibly equate winter-warm and epidemic plague as the same disease? They fail to realize that winter-warm is caused by non-seasonal qi, where illness affects people of all ages with similar symptoms, belonging to seasonal epidemic qi. Plague, however, forms after cold damage when warm qi is encountered again; although symptoms may appear similar, the etiology differs. I hereby record this.

Plague refers to a condition characterized by severe whole-body fever, mental confusion and discomfort, spreading door-to-door and village-to-village through contagion, and peaking during spring and summer. Although contracted via seasonal epidemic qi, the pathogen involved is formed by evil and toxic abnormal qi, unlike ordinary climatic anomalies such as spring cold, summer coolness, autumn heat, or winter warmth. The qi of heaven and earth rises in spring and floats in summer, inevitably containing some toxic elements. Humans live within this qi without realizing it; if their righteous qi (Zheng Qi) is deficient, they become susceptible to contagion. Alternatively, if a patient's body is hot, with steaming heat floating outward, those around them with deficient righteous qi may also become infected. However, contracting the pathogen of heaven and earth typically occurs in spring and summer, whereas contracting the pathogen from an infected person can occur at any time. Therefore, in prisons, this disease persists throughout the four seasons and is highly contagious. Those who remain uninfected do so because their internal righteous qi is solid, preventing the pathogen from invading. Nevertheless, the route of entry for this pathogen is through the mouth and nose. Consequently, the righteous qi is invaded by the pathogen, leading to stagnation, oppression, and irritation, causing the disease to manifest. Although the origin lies in the pathogen of heaven and earth, it essentially emerges from within. Thus, the cause of contraction differs from cold damage, warm-summer heat, and non-seasonal cold-epidemic catarrh. Accordingly, the treatment methods differ. For instance, Zhu Danxi used Renzhong Wan, employing tonification, dispersal, and descending methods simultaneously; *Mingyi Zazu* utilized Qingre Jiedu Tang, combining internal and external treatments. These two approaches represent the major principles for treating plague: generally, one must dispel evil qi, dissipate stagnant qi, and support righteous qi. To conflate this with seasonal epidemics (where illness affects families similarly) would be incorrect. Nowadays, many mistakenly call warm diseases and heat diseases "seasonal epidemics," and label warm toxins as plague, which is a significant error. Alas, only those with profound understanding can recognize this truth.

The Xishan Record states: "Approaching foul odors damages true qi." Sun Simiao said: "When riding a horse at night, one should bathe and change clothes before approaching children, so they do not smell the 'horse poison'; otherwise, it may cause Tian Diao Ji Jing Feng (sudden infantile convulsion)." Qian Yi said: "Do not approach infants while wearing shoes that have walked through filth." This conveys the same meaning.

In the Gui Chou year of the Yongzheng reign, epidemic qi was prevalent. The envoy governing Wu entrusted Mr. Ye with formulating this prescription, saving many lives. Contemporary people compared it to Puji Xiaodu Yin.

Mr. Ye stated: Seasonal toxins and pestilential qi correspond to the ruling celestial qi. In the Gui Chou year, Taiyin Damp Earth qi was operating, followed by Taiyang Cold Water qi. Dampness and cold combined, carrying the fire of the central movement, circulating in the intersection of qi. As solar yang failed to control the situation, epidemic qi flourished. Therefore, individuals with spleen and stomach deficiency were susceptible to this pestilential qi, which entered through the mouth, nose, skin, and hair. When the pathology transformed via dampness, symptoms included fever, yellow eyes, chest fullness, erysipelas-like rashes, and diarrhea. One should observe the tongue color; if pale white or dry and scorched in the center, the damp pathogen remains in the qi level, treat with Ganlu Xiaodu Dan. If high fever persists for ten days without resolution, accompanied by coma, delirium, and maculopapular rashes, observe the tongue; if crimson, dry, smooth, round, and hard, indicating exhaustion of fluids and essence, where cold transforms into fire and the pathogen has entered the ying (nutritive) level, treat with Shenxi Dan.