Abstract
Weiqi, defensive qi (qi defensivum, weiqi) is deployed throughout the external surfaces (extima, biao) and flows through the channels. This defensive qi (qi defensivum, weiqi) protects the body from external heteropathies (xie). It also regulates body temperature, sweating, circadian rhythm and sensory perceptions. In the system of six main channels in the Treatise on Cold Damage (Shanghan lun) a disorder of the major yang (yang maior, taiyang) is regarded as an illness of the defensive qi (qi defensivum, weiqi). In the four-levels model of Warm Diseases (morbi temperati, wenbing) a disturbance of this defensive layer (qi defensivum, weiqi) is related to the early stage of fever caused by warm pathogens (calor heteropathies, rexie) as, for example, in the case of influenza, pneumonia, Covid-19, etc. This article cites passages from the Treatise on Cold Damage (Shanghan lun) and from the doctrine of Warm Diseases (morbi temperati, wenbing) for the treatment with Chinese phytotherapy; it also describes the corresponding acupuncture points and moxibustion treatments and how the theory of defensive qi (qi defensivum, weiqi) is to be applied in the treatment of long Covid, sleep disorders, depression and anxiety, sweating and bi-syndrome.