Shen Yaozi on the 4th day of the 7th month, Chushu, Bingxu Year
The body of a vehicle is square, capable of bearing weight and providing a stable space; the wheels are round, able to rotate and quickly reach the destination. The nose of an airplane is round to move smoothly through the airflow; the body is square to provide space for bearing.
The sky is round, the earth is square; time and space, humans are between heaven and earth, and all things are in constant transformation in the interweaving of time and space. The Book of Changes says, "Heaven moves vigorously, and the gentleman strives unceasingly to strengthen himself"; it also says, "The earth is vast, and the gentleman carries things with great virtue," thus achieving completeness.
Chinese culture originates from the He and Luo rivers, "The river produces the map, the Luo produces the book," the He map is round, the Luo book is square, "maps and books" must include both round and square to broadly record everything in time and space.
Humans, with round heads and square bodies, the head symbolizes heaven, rotating continuously, the body symbolizes earth, supporting and nourishing the whole body. Hands are in the sky, flexible and skillful; feet connect to the earth, bearing and clumsy. Humans are born between heaven and earth, and the human body itself forms a small universe, corresponding to heaven and earth, each person is a proud child of heaven and earth.
The sky is round, the earth is square, this is the Dao, this is the theorem, unchanging through the ages, and how can it be merely a debate constrained by the literal form of whether the earth is round or square?