Among the striking sentences in Shelley’s A Defence of Poetry is the following:” A Poet is a nightingale, who sits in darkness and sings to cheer its own solitude with sweet sounds: his auditors are as men entranced by the melody of an unseen musician, who feel that they are moved and softened, yet know not whence or why”(861). Several things are working in this sentence that also function in To a Sky-Lark.
Stanza eight of the poem makes a clear connection to this sentence:
“Like a Poet hidden
In the light of thought,
Singing hymns unbidden,
Till the world is wrought
To sympathy with hopes and fears it heeded not”(36-40)
In Shelley’s image in the Defence, men cannot see the bird, it’s singing on its own whim, and it causes the listeners to hear something. The same elements are at work in this stanza. The word “like” in line 36 makes simile to the sky-lark, a songbird like the nightingale referenced in the Defence.
The place where this connection breaks down is in the fact that the sentence is making a metaphor while the poem describes Shelley’s imaginative explorations upon encountering a sky-lark. Investigated from another angle, I think this means that the experience Shelley has upon encountering the sky-lark’s song and using that as the launching point for so many imaginative similes is the same experience he wants to convey with his poetry. The sheer number of metaphors and similes used by the poet to express the thoughts induced by the sky-lark intimate that he ‘knows not whence or why’ it moves him so, but he intends to say at it somehow. Men are “moved and softened” by the poet/nightingale’s song, and it will take some degree of rhetoric to understand how the sounds and words make them feel the way they do.
Shelley, Percy Bysshe. “A Defence of Poetry.” and “To a Sky-Lark.” The Norton Anthology of English Literature. Ed. Lynch, Stillinger. New York: W.W. Norton & Company Inc., 2012. 835-858. Print.