The division of capital houses in the Han Dynasty.
The eighth house is easy to understand, that is, each of the parents has three boys and three girls. Qian brings the three yang hexagrams Zhenkangen, and Kun brings the three yin hexagrams Xunli Dui.
Each palace is led by the eight hexagrams above and seven hexagrams, which are from the first to the fifth life to the wandering soul to the returning soul. For example, in Qian Gong, one line changes based on the Qian hexagram in the first life, two lines change in the second life, and so on. When it changes to the extreme, it returns to Qian Gua, so there are wandering souls and returning souls.
The intention is to reflect the growth and decline of yin and yang through the changes in the yao pattern.