What role does the rhetoric used in the whole poem "Wild Goose River-My Nanny" play?

The whole poem uses rhetorical devices such as parallelism and repetition, which gradually pushes the connotation of the poem to a climax in a thrilling artistic atmosphere, especially at the end, the whole poem suddenly sublimates to a new height, giving people long-term meditation and enlightenment, which is a unique skill commonly used by Ai Qing in poetry.