聚萤映雪 — “To study diligently under difficult circumstances”

During the Jin Dynasty, Che Yin was a diligent learner from a young age. As his family was poor, they could not afford lamp oil for him to study at night. On summer evenings, he observed fireflies fluttering outside. He then captured the fireflies, placed them in a white gauze bag, and hung it above his books, using their faint light to read.

Sun Kang, a contemporary of Che Yin, also came from a poor family. On snowy nights, he would study by the light reflected from the snow outside his window.