Why should Sui calligraphy lay the foundation for Tang calligraphy on the basis of synthesizing the advantages of the previous generation?

Calligraphy in the Sui Dynasty was superior to that in the Southern and Northern Dynasties, which began in the Tang Dynasty. The calligraphy style is unique, comprehensive, and inseparable from the rules. It has both the elegance and agility of the Eastern Jin and Southern Dynasties and the neatness and vigor of the Northern Dynasties. At the beginning of the Tang Dynasty, the standard of great demeanor has been initially formed here, and the calligraphy style of the two kings began to prevail. Famous calligraphers include Ding Daohu, Shi Ling and Zhi Yong. There are thousands of words in calligraphy ink and thousands of words in classics. The inscriptions of Longzang Temple, Qifa Temple and Dong Nianpu show the calligraphy style of this period.