Part of the preface to the Book of Mountains and Seas
 

Cao Shan was a calligrapher in Yunjian in the late Yuan Dynasty. He imitated Zhong Yao in regular script and Er Wang in cursive script. It can also be said that he grew up immersed in the books of Jin people. His small regular script "Preface to the Classic of Mountains and Seas" is very innovative. Zhong Yao's small regular script is written with a flat edge and a clerical style, with subtle and plump lines. However, Cao Shanshu's "The Classic of Mountains and Seas" is written with an open edge, with thin horizontal strokes and thick vertical strokes, and slight pauses at the end of each stroke. , there are traces of scriptural style. Cao Shan's foot taps and hooks are a little heavy, even a bit exaggerated, which shows the light and heavy rhythm in writing. The structure is uneven, so the fonts are of different sizes. There are twenty-one to twenty-three characters written in a vertical line of 22.1 centimeters. The characters are closely spaced and the lines are sparse. However, due to the unevenness of the characters, it does not feel crowded. The whole writing style is simple and strict. "The Book of Classics of Mountains and Seas" is a long album. When I read it, I didn't feel dull, but felt that it was simple and lively. This has created a distance from Zhao's graceful calligraphy style.