Why is 1 a tree and 2 a tree?

According to textual research, the mathematics of the five elements is much earlier than that of the river map. The number of the river map is based on the Book of Changes, and the number of the family is based on ten days. The digital five elements in the river map are based on the combination of heaven and earth, which is different from the five elements in the current river map, that is, A has been combined into water, B is fire, C is wood, D is gold, and E is earth, that is, 1, 6 is water; 2, 7 is fire; 3, 8 is wood; 4, 9 is gold; 5 10 is soil. This is also an analysis of the principles of Yijing from another angle, which can deepen the further understanding of Yijing, but it has no practical application value. It is enough to know about it. There is no need to delve into it, wasting energy and time on it, and it is not a professional textual research. Let's find something practical to learn, hehe.