The Eight Mansions system of Feng Shui is sometimes called the East-West Group system. This is because every person or house can be categorized into either the East Group or the West Group.
People within the same Group share common positive and negative directions. People in the West Group share northwest, west, southwest and northeast as their positive directions, and north, south, southeast and east as their negative directions.
People in the East Group share north, south, southeast and east as their positive directions, and northwest, west, southwest and northeast as their negative directions.
The East Group includes residents or properties associated with the following Trigrams:
The West Group includes residents or properties associated with the following Trigrams:
Yin and Yang interact with one another to form the Four Images. A Yang line above a Yang line forms the Greater Yang Image. A Yin line above a Yang line forms the Lesser Yin Image. A Yang line above a Yin line forms the Lesser Yang Image. A Yin line above a Yin line forms the Greater Yin Image.
The Four Images interact with Yin and Yang to form the Eight Trigrams. Greater Yang interacts with Yang to form the Qian Trigram. Greater Yang interacts with Yin to form the Dui Trigram. Lesser Yin interacts with Yang to form the Li Trigram. Lesser Yin interacts with Yin to form the Zhen Trigram. Lesser Yang interacts with Yang to form the Xun Trigram. Lesser Yang interacts with Yin to form the Kan Trigram. Greater Yin interacts with Yang to form the Gen Trigram. Greater Yin interacts with Yin to form the Kun Trigram.
Note that the interactions of Greater Yin and Greater Yang with Yin and Yang form the four Trigrams associated with the West Group (Qian, Dui, Gen and Kun). The interactions between Lesser Yin and Lesser Yang with Yin and Yang form the four Trigrams that make up the East Group (Li, Zhen, Xun and Kan).