Yan Jin refers to the characteristics of Yan Zhenqing's calligraphy. Yan Zhenqing's calligraphy is full of brushwork, vigorous and free-spirited, full of vigor, just like the tendons in the human body, with toughness and strength. Therefore, Yan Jin is used to describe his calligraphy characteristics. Liu Gu refers to Liu Gongquan, whose calligraphy is sharp and vigorous, like a human bone. They are all famous masters of regular script in China. China's regular script calligraphy reached its peak in the Tang Dynasty, represented by Yan Zhenqing, and later Liu Gongquan was also influenced by Yan Zhenqing. His attainments in regular script are also very high, not inferior to Yan Zhenqing's, so later generations call it "regular script". Later generations say that learning regular script must be strict. Both of them had a great influence on the later regular script.
There are differences and connections between Yan Jin and Liu Gu. Yan Zhenqing's vigorous calligraphy is inseparable from his personality. Yan Zhenqing is upright and upright, so his calligraphy is just like his character. It is solemn and powerful, and Liu Gongquan is influenced by Yan Zhenqing, but he is a beginner of Wang Xizhi and a calligrapher of past dynasties, which is different from Yan Zhenqing. Later generations called regular script, Yan Liu, Tang poetry and Du Li. There are similarities between them, but there are also differences. They have made great contributions to China's calligraphy and provided a model for future generations to learn calligraphy.