When did calligraphy become an art?

At the end of Han Dynasty, Wei and Jin Dynasties, calligraphy was regarded as art for three basic reasons: first, calligraphers began to appear in this period, and calligraphers began to become the leader of the writing atmosphere of the times and the representative of calligraphy level; Secondly, calligraphy works designed for appreciation have been created, and practicality is not the only thing in calligraphy; Third, there are calligraphy appreciators. In addition, there are two reasons: first, the calligraphy tools and carriers suitable for creation gradually improved during this period, and the production of brush, ink, paper and inkstone was very excellent, especially after the improvement of paper in the Eastern Han Dynasty and Wei and Jin Dynasties, it was widely used in daily writing; Secondly, the literati in this period began to pay attention to calligraphy, and had some special discussions on both positive and negative aspects of calligraphy, such as the cursive script of Cui Yuan in the Eastern Han Dynasty and Zhao Yi's non-cursive script, and discussed the cursive learning phenomenon at that time. Cui Yuan's cursive script involves some universal laws of calligraphy.