"Shuo Wen Jie Zi" says: "There are cursive scripts in Han Xing". The cursive script began in the early Han dynasty, and its characteristics are: keeping the outline of characters, damaging the official rules, rushing away and rushing away quickly. Because of the meaning of grass, it is called cursive script.
Extended data:
Today's grass is also called "a book". Zhang Huaiguan said: "The style of the word (grass) is formed by strokes, occasionally interrupted, connected by blood, and its connection and climate are staggered ... The book of the world began in Zhang Boying."
The so-called "one book" in Shu Duan means that in the process of writing, cursive script is also called a book, and Zhang Zhijin's Biography (General's Post) is his masterpiece.
In Wang Xianzhi's Mid-Autumn Festival stickers and December stickers, "a book" is even more obvious. Anyway, Zhang Zhi's position in the history of calligraphy is still very high. No wonder some people call it "the sage of grass"
References:
Baidu encyclopedia _ cursive script