What do you think of Yan Zhenqing and his calligraphy?

Yan Zhenqing, born in 709 and died in 785, was born in Jingzhao Wannian (now Shaanxi). Word Chen Qing, a former Pingyuan magistrate, official to official department ministers, the surname of the prince, Lu Feng county. People also call him "Yan". His calligraphy became good at the beginning, and later he learned to write in Zhang Xu, completely getting rid of the demeanor of the early Tang Dynasty and creating a new style of calligraphy in the times. Yan Zhenqing's original calligraphy is magnificent and dignified, and its handwriting has changed from slender in the early Tang Dynasty to square and has a centripetal force. The pen is vigorous and powerful, and the central brushwork is good. Full of bones and muscles, but also sharp. Generally, horizontal painting is slightly thinner, vertical painting, point, skimming and pressing are slightly thicker. This book is magnificent in style and momentum, and has the spirit of flourishing Tang Dynasty. His cursive script is vigorous, expressive, calm and vigorous, which opens up a complete life for the cursive script after Wang School. Yan Zhenqing has many works handed down from generation to generation. The famous pen and ink regular script includes Zhushantang couplet poem post and advertisement post. There are cursive scripts, such as Sacrifice to My Nephew, Liu Zhongtie and Huzhou Tie. Among them, there are still different opinions on the authenticity of other works except the "Sacrifice to a Nephew" which is recognized as an original. But it's all flowing ink. There are many inscriptions written by Yan Zhenqing in his life, among which "Duobaota Monument" has been handed down to this day, with dignified and precise structure and beautiful appearance; "Dong Fangshuo painted a monument to praise" with a strong Qingyuan style; "Diligence Monument" is heroic and clean. In addition, there are Ma Guxian Tan Ji, Ode to Datang and Yuanjiebei. There are also many seal cutting calligraphy posts, and his works are usually found in the middle posts collected in past dynasties, such as "Competing for a seat" and "Rentie". Ji Ming's Draft for Sacrificing Nephew, cursive script, 28.2 cm long, 72.3 cm wide, 25 lines and 230 words. This post is a manuscript, originally not written as a calligraphy work, but it has become a rare masterpiece because it has no intention of writing a book. His pen is clever, natural and vivid, and careless. Therefore, this post is full of spirits, horizontal posture, magnificent brushwork and great power, and is known as the first in Yan Shuxing Grass. Yuan Xianyu once rated this post as "the second running script in the world". The original is now in the National Palace Museum in Taipei.