Like Li Bai's poems, cursive and crazy books, represented by Zhang Xu and Huai Su, flow very fast, and even the word "Li Bai" flies, which is "shocking" and pours mixed emotions into pen and ink. It is no accident that Li Bai, a poet, and Zhang Xu, a sage of grass, are equally famous. Han Yu said: "In the past, Zhang Xushan wrote cursive script ..... He had grievances in his heart and must show them in cursive script. Seeing things ... the changes of everything in the world ... are reflected in books, so the changes in Xu's books are still ghosts. " Not only Zhang Xu's Wild Grass, but also the era of calligraphy at that time. "Xuanhe Pu Shu" said that He Zhangzhi "has a good place in Caoli, where opportunities compete with nature and cannot be reached manually." Everything is romantic, creative and talented, all reappearance becomes expression, all simulation becomes lyricism, and all natural and secular material existence becomes a turbulent emotional development journey.