Teacher Cai's lecture: knowledge of five elements of traditional Chinese medicine, Yangming's atmospheric spirit, and health care of five internal organs. Chinese medicine says that the heart governs the brain. The five elements are based on the five internal organs, and the brain does not belong to the five internal organs. Only refers to nourishing the heart. As for the bone belonging to water, it is because the kidney dominates the bone, and the kidney belongs to water in the five elements. Therefore, people with kidney deficiency are prone to osteoporosis.