This idiom originates from two historical anecdotes. During the Song Dynasty, the renowned literary figure Ouyang Xiu grew up in poverty and could not afford formal schooling. His mother ingeniously taught him to read and write by drawing characters with a reed stem on sand.

Later, during the Tang Dynasty, Liu Zhongying, a diligent young scholar, studied assiduously. To help him stay awake and focused during late-night studies, his mother would make pills from bear gall, which he would hold in his mouth to refresh himself.

Both stories commend mothers who, despite difficulties, employed resourceful and dedicated methods to educate their children, eventually leading them to great achievements.