The numbers represented by fire, water, wood, gold and earth are 1 and 6, 2 and 7, 3 and 8, 4 and 9, 5 and 0 respectively. Why is this rule?

The number of all living things: the sky is full of water, and the earth is 60%; 70% of the fire days ranked second; There are three trees in the sky and 80% of the land; The land is rich in gold, and the sky is 90%; Born in five places, the ground gives birth to a percentage. So one is the quantity of water, the other is the quantity of fire, the third is the quantity of wood, the fourth is the quantity of gold, and the fifth is the quantity of soil. Six is the quantity of water, seven is the quantity of fire, eight is the quantity of wood, nine is the quantity of gold, and ten is the quantity of soil. Everything has a number, and it can only be born when it is born; Everything has a number, and it can only be realized when it can be realized. Therefore, everything has its number.