The poem's main theme is the death of a girl, though it is not a lamentation. In the first stanza, the speaker claims he does not mourn the girl's passing because now she is beyond aging and suffering. She will never grow old or lose her youthful beauty; in his mind, she will always be as she was: young and pretty.
The second stanza focuses more on the stillness of death, mentioning how the deceased can no longer move or breathe. She cannot sense the passing of the seasons, the coming of heat and cold. However, the line, "Rolled round in the earth's diurnal course, / With rocks, and stones, and trees," suggests she has become one with the natural world after being buried. Her remains will become part of nature, in a way keeping her present even in the mortal plane. She has not truly died or been lost to the world entirely.