Who became a monk when he was a child and was called "the sage of grass" in history?

Correct answer: Huai Su.

Huai Su (737 -799) was born in Lingling, Yongzhou (now Lingling, Hunan). Calligraphers in the Tang Dynasty are famous for Weeds. Together with Zhang Xu, they are called "crazy people". Li Zhimin commented: "There is a delicate god in Huai Su's cursive book escape, and there is innocence in the wild." . Huai Su became a monk when he was a child. In his leisure time after meditation, he enjoyed calligraphy, which is as famous as Zhang Xu, forming a situation in which two peaks of calligraphy coexist in the Tang Dynasty, which is also the two peaks in the history of cursive script in China. Huai Su's cursive script is thin and vigorous, flying naturally, like a whirlwind of showers. Calligraphy is ever-changing, ever-changing and has statutes. Calligraphy works handed down from ancient times include autobiographical notes, bitter bamboo shoots, Notre Dame notes, essays on books, a thousand grasses and so on.