The phrase "a bag full of snow" originated from an ancient Chinese story in the Book of Han. The story was about a boy named Nang Ying, who used white silk to make a transparent bag and put fireflies in it to light up his books while he studied. Another boy named Ying Xue used the moonlight reflected by the snow in the middle of the night to read. This story showed the protagonist's studious spirit and thirst for knowledge.