Note ↑ Taoist terms in Huang Nai are established according to the theory of five elements generating grams: five elements with five internal organs, five colors, four seasons, five prescriptions and so on. , especially the human body with five elements. The book "Five Veins of Taiming" says: "The spleen dominates the soil, which is born in fire (fire-born soil) and is gram in water (soil and water), and its color is yellow. According to the five elements: Jinshui, aquatic wood, Wood Fire and Fire Earth. Native to the spleen, yellow in color; Western metal lung, white in color; The northern water belongs to the kidney and is black in color; Southern fire belongs to the heart and the color is red. From the above, it can be seen that the spleen belongs to middle earth, and its color is yellow, so it is called "middle earth yellow". "Taiqing" Volume II Huang Zhen: "The spleen dominates the center, and the color is yellow. When you take a thousand breaths, its color is prosperous. "Note:" When you take a thousand breaths (take a thousand deep breaths a day), you can think about it once a day (imagine the real situation), regardless of the season, and there is no magic. After the spleen exists for forty-nine days, you can hide your body in the wall when you see this qi coming out of the spleen. Qing Xitai: History of Taoism in China (Chengdu: Sichuan People's Publishing House, 1993), Volume III, pp. 368-370. Li: Handbook of Taoism (Zhengzhou: Zhongzhou Ancient Books Publishing House, 1993), p. 428.