William Butler Yeats is widely acknowledged as the greatest poet of the twentieth century. He belonged to the Protestant, Anglo-Irish minority that had controlled the economic, political, social, and cultural life of Ireland since at least the end of the seventeenth century. Most members of this minority considered themselves English people who merely happened to have been born in Ireland, but Yeats was staunch in affirming his Irish nationality. Although he lived in London for fourteen years of his childhood (and kept a permanent home there during the first half of his adult life), Yeats maintained his cultural roots, featuring Irish legends and heroes in many of his poems and plays. He was equally firm in adhering to his self-image as an artist. This conviction led many to accuse him of elitism, but it also unquestionably contributed to his greatness. As fellow poet W. H. Auden noted in...