Percy Bysshe Shelley's poem "Ode to a Skylark" addresses the skylark as "blithe spirit" and declares that the skylark itself could never really have been a bird, but it is a creature which, from Heaven "or near it," "pourest thy full heart." The skylark's song, according to the speaker, is essentially divine: it is so beautiful that the speaker imagines the bird to be something beyond the earthly.
Shelley reiterates this celestial theme when he comments on the "shrill delight" of the skylark, which seems to echo around the flight of the skylark as if it were "a star of Heaven."
The sublime quality Shelley describes in the voice of the skylark, which elevates it above the song of ordinary birds, echoes a sentiment found in much Romantic poetry. Shelley's concentration in this poem is upon the extremity of emotion evoked in him by the skylark's song, to the extent that he can compare it to nothing on Earth. Indeed, he questions, "What is most like thee?", the implication being that none can truly tell. The skylark is "like a Poet hidden / In the light of thought." This seems to suggest that, like the Romantic poets, the skylark seems to be interrogating the world for whatever depths it holds and whatever emotions can be drawn forth from it. The skylark is something few could understand, and yet at the same time is equated with all of earth's own beautiful things, such as the "sound of vernal showers." So sublime is the skylark that it is both and either "Sprite or Bird," something whose song seems to contain eternal mysteries within it, while it hovers between Heaven and Earth.