In five sonnets containing four tercets (three-line units) each, the speaker addresses the west wind—the "breath of Autumn's being." He tells the wind that he admires how it scatters dead leaves and moves seeds down to the earth. At the same time, he associates the wind with death from early on in the poem, saying the dead leaves fly like ghosts and resemble crowds of sick people. The seeds, the speaker says, will lie corpse-like until the spring. He then goes on to imagine the spring itself as a trumpet player who summons buds from the earth and makes the world blossom.
Next, the speaker considers the wind's effects on the clouds in the sky. He imagines the clouds through various images, including dead leaves, angels, and the hair of a dancing girl. The speaker also pictures the night sky as the dome of a tomb, with the clouds as the arch over the tomb.
In the third sonnet, the speaker shifts his gaze to the Mediterranean Sea. He tells us—or, more precisely, he tells the wind itself—how the wind woke the sea from its slumber and uncovered the ruins in its waters. The speaker briefly comments on the beauty of these ruins, which are "overgrown with azure moss and flowers." He gives a similar treatment to the Atlantic Ocean, saying the wind agitates its surface and even causes the plant life on the ocean floor to tremble.
We encounter the most significant shift in the poem's tone thus far in the fourth sonnet, where the speaker begins to reflect on his own life. He laments that he cannot be swept up by the wind and fly like a cloud or dead life, and he says he wishes he could be a wave caused by the power of the wind. The speaker grieves for his childhood, when he had more freedom, ambition, and imagination. Back then, he says, it did not seem impossible that he could move faster than the wind itself. He calls to the wind to help lift him out of the "thorns of life," saying that age has made him "chain'd and bow'd"—a sharp contrast to the young man he apparently once was.
This appeal to the wind continues into the final sonnet, as the speaker calls on the wind to turn him into its instrument, like it has with the forest. Then, he asks the wind to transform into his own spirit, doing away with his old, "dead" ideas and inspiring new ones. Finally, he asks the wind to inspire such a change in mankind as a whole. The wind, he says, will speak through him; his own words—such as the words of this poem—will be the catalyst for revolution.
