Percy Shelley's poem "To a Sky-Lark" and John Keats's poem "Ode to a Nightingale" are both centered on nature in the form of birds. Both poems are classified as Romantic and have certain poetic elements in common, but in addition both poems have differences in style and in theme that differentiate them clearly. Both poets are spurred to react and to write because of their encounter with a bird. Shelley is addressing the bird that excites his interest more directly, while Keats turns to reverie because of the song of the nightingale more than the nightingale itself. In the latter case, the song of the poet has a different tone from the song of the bird--the joy of the bird becomes a contemplative song for the poet. Each poet begins with the reality of the bird or its song and then uses that as a beginning point for aesthetic and philosophic speculation, delving in each case into his own inner world for a response to the stimulus offered by the sky-lark or the nightingale.
Shelley begins his poem with a direct address to the skylark, and it is the skylark's song that is of greatest interest to this poet just as it will be to Keats. Shelley makes a direct reference to the song as an example of "unpremeditated art," which might also be the term to describe the goal of the Romantic poet--he or she would like each poem to appear to be unpremeditated and to flow from an emotional response to nature ore than from calculated rational design. In this, these poets are imitating nature, or their perception of nature, and the skylark is for Shelley a representation of the purity of the art of nature, offering a song that is pure expression.
The poetic pattern used by Shelley develops a series of five-line stanzas. Each begins with a trochaic measure with a stressed followed by an unstressed syllable, followed by two more trochaic measures. Beginning with a stressed syllable emphasizes the word "Hail" in the first line and the idea t...