Source: Allison, Jonathan. “The Last Line of ‘Sailing to Byzantium’: A New Source.” Yeats: An Annual of Critical and Textual Studies vol. 8, Richard J. Finneran, pp. 319-21. Ann Arbor, Michigan: The University of Michigan Press, 1990.

In the following essay, Allison examines the source for the last line of Yeats's poem.

The source of the last line of Yeats's “Sailing to Byzantium”—”Of what is past, or passing, or to come” (P 194)—is usually attributed to Blake or Shelley, though there are also several possible sources of the line in Shakespeare's plays.¹ A more recent possible source, however, may be found in a lecture delivered by John Butler Yeats in 1906 to the Royal Hibernian Academy, Dublin, published in Sanachie in 1907 and again in Essays Irish and American in 1918.²

Yeats may have attended the 1906 lecture in Dublin, or he may have read it when published in 1907 or thereafter.³ He possessed...