Calligraphy is mainly positive, supplemented by edges. The center is probably your pen tip, but this statement is wrong, because the pen tip is a very small range, and there is pressure in the actual writing process, and the degree of pressure can reach about half the length of the whole pen tip, so it cannot be called writing with a pen tip. The correct statement is that the pen is perpendicular to the paper, and the direction of the nib is just opposite to the direction of the pen, which is the center.
The strength of the center's writing, the so-called leakage marks, cone painting sand and Wan Liyun, can only be written by the center.