The phrase "Spring silkworms must weave until they die" is based on the folk song () of the Southern Dynasties.

Answer: Bi Xing

Analysis: in the sentence "Spring silkworms die", the metaphor of folk songs in the Southern Dynasties is used. The two symbolic images of "Spring Silkworm" and "Candle Torch" are extremely iron by using the method of contrast. Bixing is the traditional expression of China's poetry. The application of Bixing technique enhances the vividness and distinctiveness of ancient poetry, and increases its charm and image appeal.