What is the relationship between the repetitive form of The Book of Songs and the thoughts and feelings expressed?

It better shows the author's mood of searching repeatedly but not getting it. There are three chapters in the whole poem, and only a few words are changed in each chapter, which not only plays the artistic effect of compound sentences, repeated chanting and singing three sighs, but also plays the role of constantly promoting poetry. From "the white dew is frost" to "the white dew is not full" and then to "the white dew is not full", this is the passage of time, symbolizing the long-term gaze and pursuit of the lyric hero; From "on the water side" to "on the water side", then to "on the water side", from "in the middle of the water", to "on the water side" and then to "on the water side", this is a change of location and symbolizes the elusive Iraqi people. From "Road Obstacles Are Long" to "Road Obstacles are Connected" and then to "Road Obstacles are Right", it is to repeatedly render the difficulty of the pursuit process to highlight the indomitable spirit of the lyric hero. Repetition of sentences and progressive layers are common expressions of folk songs in The Book of Songs. In poetry, such as "gray" and "sadness" are skillfully used to make