Dampness evil harms people, mostly due to exposure to mist and dew, or sweating and wet clothes, or working in water, or wading in water and getting rained on, or living in damp places. Suwen-Yinyang Yingxiang Da Lun states: "The dampness of the earth, when felt, harms the skin, flesh, tendons, and vessels," pointing out the transmission and change pattern of external dampness invading the human body from the exterior to the interior. Generally, it first causes damp qi depression to harm the muscle surface, then the external dampness transmits inward, either blocking the meridians and causing pain and spasms; or adhering to the bones and tendons causing fixed arthralgia; or damp evil stagnating internally, clear yang being obstructed, and becoming blocked and unmanifested; or damp evil harming the middle, causing dysfunction of the spleen in transportation; or clouding the upper and flowing downward, damp stagnation in the triple energizer; or damp turbidity pouring downward, leading to various pathological changes. Moreover, the spleen is the organ of damp earth, and the qi of damp earth mutually resonates, so although damp evil diseases initially come from external exposure, they ultimately return to the spleen and stomach. Therefore, diseases caused by external dampness often manifest symptoms of spleen and stomach disorders.