Zhang Xu was a calligrapher in the Tang Dynasty. Born in the third year of Shang Dynasty (675), he died in the ninth year of Emperor Xuanzong Tianbao (750). At the beginning, he was the commander-in-chief of Changshu, named "Zhang Changshi", and later he was the Emperor Wu of Jin Dynasty. His mother Lu is the niece of the calligrapher in the early Tang Dynasty, that is, the granddaughter of Yu Shinan. Lu's books have been handed down from generation to generation, which is famous in history. Zhang Xu is free and easy, generous, outstanding, brilliant and knowledgeable. Du Fu befriended Li Bai and He Hao, and was listed as the "Eight Immortals of Drinking". He is a master of cursive script with great personality. Because he is often drunk, clamoring for madness, then writing books, and even writing with his hair dipped in ink, he has the nickname "Zhang Dian". After Huai Su inherited and developed his brushwork, he also got his name from cursive script and called it "drunk". Zhang Xu is unrestrained, likes to drink, often dances after getting drunk, and then returns to the table with a pen and ink. Some people called him rude and gave him a crazy nickname. In fact, he is very careful. He believes that everything he touches in his daily life can inspire his writing. To get something occasionally is to melt it into your own calligraphy. At that time, as long as people got a piece of his paper, they all regarded it as a treasure, and it was hereditary and true. At that time, Zhang Xu had a neighbor and his family was very poor. I heard that Zhang Xu was very generous, so I wrote to Zhang Xu, hoping to get his support. Zhang Xu sympathized with his neighbor, so he said in his letter: You only need to say that this letter was written by Zhang Xu, and the asking price can be several hundred gold. Neighbors sold letters in the street according to his words and sold them out in less than half a day. The neighbors are happy to go home, and thank Zhang Xu very much. Zhang Xu's calligraphy began with Zhangzhi and Erwang, with cursive script as the highest achievement. History is called "the sage of grass". He himself is proud of inheriting the tradition of "two kings" and writes very well. On the other hand, he imitated Zhang Zhi's cursive art and created an unpredictable wild grass, which shocked the world. According to legend, he saw the princess arguing with her husband, and he heard the advocacy and got the meaning of brushwork; When I was in Yexian County, Henan Province, I loved watching Gong Sundaniang dance the sword of Xihe River, so I got the grass god. Yan Zhenqing resigned twice and asked him for his brushwork. Zhang Xu is a pure artist. He pours his emotions into stippling, and no one looks at it, and he is as intoxicated as a madman. Tang Hanyu praised in "Preface to Send a Noble Sage to a Master": "Emotion, embarrassment, sadness, happiness, resentment, longing, drunkenness, boredom and injustice, if moving in the heart, must be expressed in cursive script. Looking at things, we can see mountains and rivers, cliffs and canyons, birds, animals, insects, fish and flowers, the sun, the moon and stars, storms and fires, lightning and thunder, singing and dancing battles, and changes in heaven and earth. Congratulations, one is in one book, so the book of Xu is still as unpredictable as ghosts and gods, and it will eventually be praised by later generations. " This is a true portrayal of a real artist's obsession with art. No wonder later generations talked about calligraphy in the Tang Dynasty and praised Europe, Yu, Chu, Yan, Liu and Su, but they all admired Zhang Xu, which is unique in the history of art. He was honored as a "sage of grass" by later generations.