In an earlier poem entitled “Mutability,” Shelley used clouds as a symbol of impermanence and likened them to human life, which is never the same from one day to the next. In Prometheus Unbound the cloud takes on a different meaning as a symbol of the material human form, which is illuminated by the transcendent light that shines from within it. “The Cloud” builds on both these meanings and adds a third. Certainly the cloud is transient, but impermanence is not the last word; everything in the poem goes through a cycle of dissolution and rebirth; nothing is forever lost. This is why the cloud is depicted as laughing: It knows this truth, and its laughter suggests that the essential reality of life, underlying all temporal phenomena, even its apparently dark or distressing elements, is bliss and joy. This bliss is propelled through the material world through the power of love—another belief that Shelley expressed frequently, especially in Prometheus Unbound.
The image of the cloud at sunset, resting with wings folded, “as still as a brooding dove,” is also significant. It is a clear allusion to Book I of Paradise Lost, by John Milton, in which the Holy Spirit is described at the creation as sitting “Dove-likebrooding on the vast Abyss.” The image suggests that the cloud is also a metaphor for the creative energy, which elsewhere in his writings Shelley saw embodied in an absolute One that effortlessly manifests its power through the material world. This power is usually hidden, as, for example, in “Hymn to Intellectual Beauty,” but it is indestructible—the eternal dimension of existence which persists unchanged through all the cycles the material world undergoes. In this sense the cloud resembles the skylark in “To a Skylark,” a poem Shelley wrote at about the same time that he wrote “The Cloud.” The skylark sings in joy; its song comes not from itself but from an unmanifest creative source that merely uses the bird as its instrument. So it is with the cloud. All these meanings combine to suggest a world in which truth is effortlessly manifested and joyously perceived, an unpolluted paradise free of the ugliness that ignorant humans, who mistake illusion for reality, appear (but only appear) to impose upon it.