“Ode to the West Wind” is a fine example of Shelley’s mytho-poetic imagination at work. The west wind is a spirit, as is the skylark. It possesses great powers and for this very reason Shelley can pray to it for what he feels he is deeply in need of. Shelley desires the irresistible power of the wind to spread his ideas of liberty and democracy.
The poem begins with three cantos describing the wind's effects upon earth, air, and ocean. The poet invokes the “wild West Wind” of autumn, which scatters the dead leaves and spreads seeds so that they may be nurtured by the spring, and calls the wind a “destroyer and preserver”. In the second canto, Shelley expands his vision from the earthly scene with the leaves before him to take in the vaster commotion of the skies. The clouds now reflect the image of the swirling leaves; this is a parallelism that lifts our attention from the finite world into the macrocosm. The clouds are more unstable and bigger than the leaves and they can be seen as messengers of rain and lightning. The poet calls the wind the “dirge / Of the dying year,” and describes how it stirs up violent storms. The third canto refers to the effect of west wind in the water. It stirs the Mediterranean from “his summer dreams,” and cleaves the Atlantic into choppy chasms, making the “sapless foliage” of the ocean tremble.
In the fourth canto, Shelley is speaking directly to the wind, pleading to lift him “as a wave, a leaf, a cloud!”—for though he is like the wind at heart, untamable and proud—he is now chained and bowed with the weight of his hours upon the earth.
In the fifth section, the poet then takes a remarkable turn, transforming the wind into a metaphor for his own art, the expressive capacity that drives “dead thoughts” like “withered leaves” over the universe, to “quicken a new birth”—that is, to quicken the coming of the spring. Here the spring season is a metaphor for a “spring” of human consciousness, imagination, liberty, or morality—all the things Shelley hoped his art could help to bring about in the human mind. Shelley asks the wind to be his spirit, and in the same movement he makes it his metaphorical spirit, his poetic faculty, which will play him like a musical instrument, the way the wind strums the leaves of the trees. The thematic implication is significant. In this poem, Shelley explicitly links nature with art by finding powerful natural metaphors with which to express his ideas about the power, import, quality, and ultimate effect of aesthetic expression.
Each of the five parts of “Ode to the West Wind” contains five stanzas—four three-line stanzas and a two-line couplet, all metered in iambic pentameter. The rhyme scheme in each part follows a pattern known as terza rima, the three-line rhyme scheme employed by Dante in his Divine Comedy. In the three-line terza rima stanza, the first and third lines rhyme, and the middle line does not; then the end sound of that middle line is employed as the rhyme for the first and third lines in the next stanza. The final couplet rhymes with the middle line of the last three-line stanza. Thus each of the seven parts of “Ode to the West Wind” follows this scheme: ABA BCB CDC DED EE.
“Ode to the West Wind” is a highly controlled text about the role of the poet as the agent of political and moral change. This was a subject Shelley wrote a great deal about, especially around 1819, with this strongest version of it articulated the last famous lines of his "Defence of Poetry": "Poets are the hierophants of an unapprehended inspiration; the mirrors of the gigantic shadows which futurity casts upon the present... Poets are the unacknowledged legislators of the world."