Harold Bloom writes:
The "infirmity is of the muse itself, with its singed wings, able at best to render the Thou by a swan song of self-immolation. The attempt to express "all that thou art" proceeds again by a multiplicity of image-makings, precariously linked by a formula akin to that of the "narrowing image." The Thou of Emilia is likened to a series of Thous surrounded or encased by experiential It's. A sealed and secret well, its waters separated off from the surrounding gloom; a fixed star in the moving heavens; a smile amid frowns; a gentle tone amid rude voices; a light amid darkness; all of these Thou's are solitudes, refuges, delights, sheltering the I from the universe of things. (212)
Bloom, Harold. Shelley's Mythmaking. Ithaca: Cornell UP, 1969.