Why does Shelly called the west wind a destroyer and a preserver?

Shelley refers to the west wind as a "destroyer" because it has the power to sweep away the old and decaying elements of nature, symbolizing change and the end of cycles. At the same time, it is a "preserver" because it also enables new growth and regeneration, carrying seeds that will lead to renewal and life. This duality highlights the west wind's role in both destruction and creation, reflecting the interconnectedness of these forces in the natural world.