1. In the Book of Changes, which is called the cultural source of China, black represents the sky and the north where Tiandi lives. Black has also become the most important color in the Book of Changes.
2. Each hexagram in the Book of Changes has its own color as a representative. Among them, the divination of Kangua shows that the middle Yang is surrounded by the yin on both sides, and the light is in darkness, so it is black.