1. W. B. Yeats, ‘Clarence Mangan’s Love Affair’, in Uncollected Prose by W. B. Yeats, ed. John P. Frayne, 2 vols (London: Macmillan, 1970), I, p. 195.
2. Thomas Alan Shippey, ‘Listening to the Nightingale’, Comparative Literature, 22, 1 (1970), p. 49.
3. Frank Doggett, ‘Romanticism’s Singing Bird’, Studies in English Literature 1500–1900, 14, 4 (Autumn 1974), p. 550.
4. James McKusick, ‘The Return of the Nightingale’, The Wordsworth Circle, 38 (2007), p. 37.
5. For the ideological significance of birds in the Enlightenment and Romantic periods, see Lorenz Eitner, ‘Cages, Prisons, and Captives in Eighteenth-Century Art’, in Images of Romanticism, eds. Karl Kroeber and William Walling (New Haven: Yale University Press, 1978), pp. 13–38; and