There has been a saying about the "Four Gates" in "Five Elements of Justice" for a long time: "The Book of Bing says that if the yang is born in Jiazi, if it is less than Xuhai, it is still the gate of heaven. If the yin is born in Jiawu, if it is less than Chensi, it is still the local household. If Jiayin in the Yang realm is less than Zi Chou, it is still a ghost gate; if Jiashen in the Yin realm is less than Wuwei, it is still a human gate. "It coincides with the void of Sixty Jiazi. Sixty Jiazi is an ancient Chinese calendar. , sixty is a cycle, and this cycle also exists in months and days, that is, by sixty days and sixty years, it returns to the original stems and branches of the previous cycle. When counting years, it is called Huanli. When counting days, ten days are often used as the starting point, which is called a ten-day period. Since there are ten heavenly stems and twelve earthly branches, two earthly branches in one ten-day period do not have corresponding heavenly stems to match them, which are called "lonely" and "empty". For example, in the ten days of "Jiazi", the void is "Xuhai". In the ten days of "Jiaxu", the void was "Shenyou". In the ten days of "Jiashen", the void is "Wuwei". And so on. From the Bagua directions corresponding to the Heavenly Stems and Earthly Branches, we can see that "Xuhai" is the "Qian" position in the acquired Bagua, which means the sky, and Kongsu means void, emptiness, which is synonymous with the void of the "door" in the building, so " "Xuhai" gave it the title of "Tianmen". In the same way, in the ten days of "Jiawu", "Chensi" was the "Xun" position in the Eight Diagrams of the day after tomorrow, which was exactly opposite to Qian, and was extended to mean earth, so "Chensi" was given the title of "Dimen" (later also known as Be a "local household"). However, here "Wuwei" is regarded as the "human gate" and "Zichou" is regarded as the "ghost gate", which is inconsistent with the Feng Shui theory. We speculate from the Bagua orientation map that the changes in the "human gate" and "ghost gate" in Feng Shui theory may be related to the concept of the four corners. In the Bagua orientation, east, west, south, and north are the four positive directions, and northeast, southeast, northwest, and southwest are As the four corners, if Xuhai, northwest, and Qian are "Tianmen", and the opposite "Chensi", Southeast, and Xun are "dihu", then the remaining two corners should be southwest, "Weishen" and northeast, "Chouyin" . So the "Human Gate" and "Ghost Gate" in the "Five Elements" above were moved one space clockwise respectively to form the four corners. Misalignment and shifting in orientation are one of the commonly used "transformation" techniques in Feng Shui. "Weishen" (Southwest) is the "Kun" position in acquired gossip, which means "earth" and is related to "people", so "Weishen" is given the meaning of "land" and "people", and is called "Renmen" "The living "people" are opposite to the dead, and the "Chou Yin" (Northeast, Gen position) opposite to them is called the "Ghost Gate".