In nature, Li diagram represents fire, and in the middle of it is dotted line. Just like the characteristics of fire, the middle temperature of fire is lower than the outside temperature. At the same time, in the five elements, Li diagram also represents the five elements of fire; in the northern hemisphere, the temperature in the south is higher than that in the north, so the position of Li diagram represents the positive south, which is summarized by the ancients according to the natural law and life, so all things cannot leave the natural law, which is the mysterious place of the book of changes and the eight diagrams.