Multidimensional Explanation to the Transformation into Birds Instead of Butterflies in "Liu Yin Ji"

Sichuan opera "Liu Yin Ji" is universally acknowledged as a transformation of "The Butterfly Lovers" (Liang Shanbo and Zhu Yingtai). But its ending with the couple's transformation into birds instead of butterflies incurs both much-touted and much-clouted remarks. The essay tries to explore the ending from perspectives of plot arrangement, succession of tradition, inevitability and possible origin to reveal the unique cultural connotation conveyed by "Liu Yin Ji".