How did calligraphers in past dynasties comment on the words of emperor statues?

The characters of the emperor's portrait have distinctive characteristics and high achievements, which have been well received by calligraphers of all ages. For example, Yang Xin of the Southern Song Dynasty said, "Wu Can is the emperor of grass, and the world is called calm and happy." Tang Doufu described his writing as "like a dragon biting, stretching and reopening". Zhang Huai said: "The official script of the right army is the same, but the words are different; Hugh Cao, with all the characters in one form, is the same, and each makes its own extreme. "