Eighteen days before beginning of spring, beginning of winter, Changsha and beginning of autumn.

Beginning of spring, beginning of winter, Changxia, beginning of autumn, 18 days ago, indicating the king of the earth. The earth king is a supplement to the twenty-four solar terms. According to the five elements, wood, water, fire and gold are based on each other for the time being, and there is no literature on soil for the time being. Therefore, in every four seasons, there are 18 days designated as belonging to the soil, and the whole year is 72 days. It's called the king of the earth these days. Wood, water, fire and gold are reduced by 18 days every quarter, leaving about 73 days, thus successfully dividing the whole year into five parts. This is the "local emperor" in Hakka folklore. During this time, you can't break ground to build a house, or start work on the wall, and so on.

The ancients thought that soil was the most important of the five elements, which could produce wood, gold, fire and water. Therefore, the couplet of the land god is "the earth can give birth to everything, and the earth can create thousands of auspicious things." The "Shout Soul Pivot Sutra" says that water, fire, wood and gold are all made of earth, so earth is the sum of five elements, which is suitable for four seasons and months.

As far as orientation is concerned, the center is earth, and the four corners are ugly, that is, gathering in the middle and scattered in four dimensions, borrowing soil can give birth to the meaning of Jin Mu's fire and water. That is to say, this 18 is the time when the soil is prosperous, that is, when the soil is the most powerful.