The circle turns to talk about the way calligraphy uses a pen. When we write, we can use the method of circular or square folding. Fang Bi has angles and bones.
As a form of calligraphy, the use of pen circle appeared very early, which can be traced back to Oracle Bone Inscriptions and Zhong Dingwen, but it was only an accidental stroke form at that time, and there was no special artistic expression intention. It was not until Qin Shihuang unified the whole country and designated Xiao Zhuan as the official designated character that the stroke shape of calligraphy was very particular.