Blake packs various themes into this narrative poem, many of which were longstanding preoccupations of his. Certainly, innocence and experience is key here. Thel, the protagonist, is defined by her "virgin" state and her "paleness," both elements which represent her purity and innocence. The youngest of several daughters, her feminine chastity is a symbol of innocence. She wants to understand why things on earth are so transient and how people (and other natural elements) can stand to exist in a way that seems to have no meaning. She wants to know if there is more to existence than this world, and she accepts the Clod of Clay's invitation to enter her house with her "virgin feet."

When she does so, however, and sees the "couches of the dead" in a land that is entirely sorrow and no smiles, Thel changes her mind. This experience and understanding she had sought is horrifying to her, particularly when she hears a disembodied voice ask questions which are similar to, but a darker progression of, the ones she had asked herself. Why are we so corruptible? Why is it that we respond to "honey" poured like poison into our ears? Unable to stand it, Thel turns and flees. Symbolically, she is returning from the valley of experience back to the vales of her innocence, but as the story ends here, we have no way of knowing whether such a journey back will really be possible. Once we have gained knowledge, can we ever recapture innocence again?

Other themes in this poem include transience—something with which Thel is preoccupied, as she wonders why fleeting things like clouds and lilies can stand to exist so briefly—and the natural cycle of life. The cloud explains to Thel that, while he may appear only briefly in the sky, he goes on to greater "raptures" as he becomes rain and then becomes part of the flowers. The Clod explains to Thel that even worms are loved by God and that we should not live for ourselves but for others. As such, every life is valuable because it has played a role in the grander scheme of things. Thel thinks this is inadequate and wants to understand more. Of course, however, having gone on to death and found it as full of sorrow and questions as her own world, Thel rejects what she has learned and turns away from it.