What does "Wandering Clouds Startle the Dragon" mean?

The meaning of Wandering Clouds Startling the Dragon: [yóuyúnjīnglóng]

Describes exquisite calligraphy. Encyclopedia explanation of "Wandering Cloud Startled the Dragon":

"Wandering Cloud Startled the Dragon", pronounced "yóuyúnjīnglóng", is a Chinese word that comes from the "Book of Jin·The Biography of Wang Xizhi" and describes the exquisite calligraphy. Detailed explanation of "You Yun startled the dragon": "You Yun startled the dragon" [yóu yún jīng lóng]

Describes the exquisite calligraphy. The source of "Wandering Clouds Startled the Dragon":

"Book of Jin·Biography of Wang Xizhi": "The commentator said that the style of his writing is as floating as a wandering cloud and as powerful as a startling dragon."