What flavor of the times has Yan Zhenqing's calligraphy permeated?

Yan Zhenqing's calligraphy is a combination of the northern monument and the southern post. While studying the calligraphy works of famous calligraphers such as Ou Yangxun and Chu Suiliang, he also absorbed elements such as Mount Tai and Stone Valley Diamond Sutra. At the same time, he studied under the famous cursive writer Zhang Xu, and became proficient in all kinds of fonts, resulting in a work and a style. There is the beauty of thinness and hardness, and there is also the beauty of fullness. He inherited Wang Xizhi's square folding pen of the right army and developed the round folding pen of the right army.