Mutability is a symbol of ultimate power; it controls humans and their universe and is the reason why their moods and beings shift and swerve. Life isn’t stable, and mutability has no trouble disrupting any attempts at permanence. When the word appears in the poem, it’s the last word, so mutability has the final say. There is no going beyond it. The poem doesn’t keep going because nothing exists beyond mutability or, in the words of Shelley’s speaker, “Nought may endure but Mutability” (Line 111).

Only mutability has the power to survive. The speaker reinforces mutability’s unrivaled authority by turning the common noun into a proper noun. Through capitalizing mutability, it becomes Mutability, and it makes it seem like Mutability is a specific entity or god. Although Shelley critiqued organized religion, he was deeply spiritual, and the elevation of mutuality to Mutability suggests change is the omniscient force in the human world. What’s almighty and all-powerful is Mutability.

Although Mutability doesn’t explicitly appear until the very end, it manifests when the “[n]ight closes round” (Line 4) and vanquishes the clouds. As a symbol of power, night represents Mutability. Night serves the same purpose as Mutability because it creates change.