The meaning is a metaphor for studying diligently.

Source: "New Tang Book·Li Mi Biography" by Ouyang Xiu, Song Qi and others of the Song Dynasty.

During the reign of Emperor Yang Guang of Chen Yang, Li Mi served as the guard of the East Palace. One day, Yang Guang came to court and asked General Yu Wenshu of Zuo Yiwei: "Who is the black-faced young man standing in the left guard?"

Yuwenshu said: "It is Li Mi, the son of the former minister Li Kuan. . ”

“This man is standing there looking around. I think he is not an ordinary person, so I cannot let him be a guard.”

A few days later, Yu Wenshu said to Li Mi: "Your ancestors have been officials for several generations. You should find a way out through talent and learning. Why do you need to be a guard?"

Li Mi resigned from his post and studied hard. One day, he rode on horseback. He was riding an ox to Goushan Mountain. There was a "Book of Han" hanging on the horns of the ox. He was reading it while walking and was met by Yang Su, the Duke of Yue.

After talking with Li Mi, Yang Su felt that Li Mi was a genius. When he came back, he said to his son Yang Xuangan, "Li Mi is not an idle person."

So Yang Xuangan became close friends with Li Mi. . Yang Xuangan was later ordered to station in Liyang to supervise grain transportation. He took Li Mi there. Under Li Mi's instigation and planning, he rose up against the Sui Dynasty. He was defeated and killed soon after, and Li Mi was arrested. However, he escaped during the escort and defected to the peasant uprising. Army——Wagang Army.

Shortly after Li Mi arrived at the Wagang Army, his talents immediately became apparent and he won the trust of Zhai Rang, the leader of the Wagang Army. Later, he was unanimously elected as the leader of the rebel army.