"It is more expensive than treasure, and books are more beautiful than mirrors." What do you mean?

"China is a country of porcelain, and the peak of porcelain industry is this capital ... more expensive than treasures, more beautiful than mirrors and more beautiful than paintings." This is a poem written by Mr. Guo Moruo 1965 for the exquisite ceramic art when he visited Jingdezhen. Compared with the paintings of Hao Jing and Guan Tong and the characters of Su Shi and Dongpo, ceramic materials have a high evaluation, which shows the expressive force of calligraphy art.