This is used to describe the calligraphy of Wang Xizhi, the sage of calligraphy
Wang Xizhi has profound attainments in real calligraphy, cursive calligraphy, and all kinds of calligraphy. His real calligraphy is clever and dense, opening up a new realm; his grass is long, thick and slender; his running script is charming and vigorous. People call his calligraphy "floating like floating clouds, as powerful as a frightening dragon"; "dragon leaps over the sky gate, tiger lies in the Phoenix Pavilion".