Why do dragons and snakes pair up in the Old Yellow Calendar?

If a dragon is redundant, it is a snake without claws. On the contrary! Long Zaitian, the snake is on the ground. Since Pangu opened the sky, there have been eight diagrams about the book of He Tu Luo and eight diagrams about Wang Wen, such as Gan Kun leaving the earthquake, in which Gan is the sky, Yang is the earth, and Kun is the earth. For yin. Yin and yang accompany each other. Like dragons and snakes

At present, dragons are Chen, earth, snakes are fire, and fire is earth, that's right!