What are the characteristics of the works of Zhang Xu and Yan Zhenqing?

Zhang Xu: His calligraphy originated from "Two Kings" and is original and innovative. His regular script is accurate. The rules are extreme, and Huang Gu is called "the first in the Tang Dynasty". If his regular script is more inheritance than creation, then his cursive script is a great innovation and development in calligraphy. Han Yu said, "Xu is good at cursive writing, but he can't cure his book." Change is like ghosts and gods, so don't be arrogant. " Du Fu wrote in Song of the Eight Immortals: "Zhang Xu's three cups of grass are sacred. He waved his paper like a cloud before taking off his hat to reveal the top of the maharaja. " He can sublimate the art of calligraphy to the artistic realm of expressing calligraphers' thoughts and feelings with abstract points and lines. In the art of calligraphy, his handwriting seems strange but not strange. The key is that the pen for stippling completely conforms to the traditional rules. It can be said that he used traditional techniques to express his personality and became a creative calligrapher worthy of his own time in calligraphy. Broad, fresh and unrestrained, far more than the previous calligraphers' works, with a strong flavor of the prosperous Tang Dynasty. Yan Zhenqing: His regular script is contrary to the calligraphy style of the early Tang Dynasty. With the brush of seal script, it turns thin and hard into vigorous and vigorous, with broad and magnificent structure, strong and awe-inspiring, dignified and majestic. His running script is rich and vigorous, and this style also embodies the prosperous style of the Tang Dynasty empire, which is a typical example of the perfect combination of calligraphy beauty and personality beauty.