W. B. Yeats (1865–1939) is one of the foremost poets in English of the twentieth century, and much of that reputation rests on his achievement in the last twenty years of his life. Although some of his early lyrics remain among readers’ favorites and part of his strength lies in the range and development of his whole career, had he fallen silent at the age of fifty in 1915, he would not be such a major figure. Poems such as “The Second Coming,” “Meditations in Time of Civil War,” “Leda and the Swan,” “Sailing to Byzantium,” “A Prayer for My Daughter, “Among School Children,” “A Dialogue of Self and Soul,” and “Under Ben Bulben” come from a sustained industry and renewed vigor that saw him producing great poetry until his final days. The poetry continues a shift in tone and style that had started some years earlier but gains a confidence and gravity of voice. Yeats's will to continue as an active writer was never in doubt, but relatively few poets continue to write into middle age with the fertility of their younger years, and even fewer produce work that is widely accounted as among their best.

The incredible experience was an experiment with automatic writing by his new wife, George, in 1917 and the messages that her hand wrote and continued to write for many months afterwards. The details and nature of these communications are examined in the following chapters, but they were sufficiently overwhelming that Yeats dedicated years to gathering, arranging, and expounding what they expressed, and the import of their teachings affected his life and poetry both directly and indirectly. Images and ideas drawn from the automatic writing started to appear almost immediately in his poetry, prose and drama, and they continued to inform his art for the rest of his life, often at a less obvious level.