The pen is full of ink: the pen and ink are used very freely and fully. It mostly describes calligraphy and poetry as smooth and vigorous.
The pen moves the dragon and the snake: The pen depicts the dragon and the snake leaping. Describes the calligraphy style as vigorous and free-spirited. He also writes on behalf of the commander.
First written about Huang Ting: Huang Ting: Taoist classic "Huang Ting Jing", Jin people have "Huang Ting Jing" small regular script calligraphy. In old times, when commenting on calligraphy, there was an idiom: "The first time I wrote Huang Ting, it was just right." Later it was used as a metaphor for doing things just right.