[Composed at Bishopsgate Heath, near Windsor Park, 1815 (autumn);
published, as the title-piece of a slender volume containing other
poems (see "Biographical List", by Baldwin, Cradock and Joy, London,
1816 (March). Reprinted--the first edition being sold out--amongst the
"Posthumous Poems", 1824. Sources of the text are (1) the editio
princeps, 1816; (2) "Posthumous Poems", 1824; (3) "Poetical Works",
1839, editions 1st and 2nd. For (2) and (3) Mrs. Shelley is
responsible.]