It tells the story of Kuang Heng in the Western Han Dynasty.

In the Western Han Dynasty, there was a farmer's child named Kuang Heng. One night, Kuang Heng was lying in bed with a book he had read during the day. On his back, he suddenly saw a ray of light coming in from the east wall. He stood up and walked to the wall. It turned out that the neighbor's lights came through the cracks in the wall. So Kuang Heng picked up a knife and dug a crack in the wall. In this way, the light passing through is also greater.

Kuang Heng studied so hard that he became a great scholar.