The meaning of the word "bi"

Bi, the name of ancient jade. It is also made of stained glass. A flat circle with a hole in the middle. Bi is a jade ring used by the Han people in ancient times. Any circular jade with a radius three times that of the sky is called Bi. Erya says, "Meat is twice as good as jade, meat is twice as good as jade, and meat is twice as good as ring." . The so-called meat refers to the edge, and the good refers to the hole. In fact, this ratio is only ideal, and the actual unearthed jade rarely meets this ratio. Bi, an ancient object name, is usually made of jade, but it is also made of glass. The shape of the wall is usually oblate, with a round hole in the middle, but there are also contour walls, that is, buttons with dragon or other shapes are carved outside the circular contour. Usually mined on ore hills. In Shuowen, Shi Bi said: "Ruiyu is also a round instrument." Xing Yushu: "Meat, edge, good, hole, edge is twice as big as hole." Here, the shape of the wall is very clear. "Meat" refers to the surrounding edge, "good" refers to the hole inside, and the edge is twice the aperture. In fact, this ratio is only ideal, and the actual unearthed jade rarely meets this ratio. Similar to this vessel are Yuyuan and Yuhuan, whose names are determined by the size of the central circular hole. The big hole is the yuan, and the small hole is the finish. The aperture of the ring is equal to the edge of the jade part.