Mary Shelley, in the note she supplied to the poem, properly characterizes The Witch of Atlas as “wildly fanciful, full of brilliant imagery,” and burgeoning with “fantastic ideas.” Rather misleading is her further statement that its source materials were borrowed “from sunrise or sunset, from the yellow moonshine, or paly twilight,” a kind of emotional garner from Shelley's rambles “in the sunny land he so much loved.” For The Witch is as literary a poem in its origins as Shelley ever wrote. It teems with images which suggest Spenser, Milton, and Shakespeare, as well as Virgil, Ovid, Lucan, Herodotus, and Pliny. A recent article by Professor Lowes indicates that Keats's Endymion should be added to the list of sources, with what justification Professor Clark's ensuing article makes clear.
