William Butler Yeats published "The Circus Animals' Desertion" in a collection called Last Poems, which was published in 1939—the year of his death at age 70. Yeats was a legendary Irish poet who wrote profoundly about the Irish fight for independence. He was also an impassioned believer in occultism and various forms of magic and esoteric thought, and many of these themes come up in his poems.
Yeats is often understood as a poet who bridges the gap between pre-World War I romanticism and postwar disillusionment, and "The Circus Animals' Desertion" emphasizes a feeling of disillusionment that characterized many works of the time.
The poem is written in iambic pentameter, and contains three sections, each written in the ottava rima style of eight lines of iambic pentameter laid out in an ABABCC format. Ottava rima is traditionally used for epic poems, like the kinds that tell stories of great myths, but "The Circus Animals' Desertion" is really about the dissolution and falsities of mythology—just one of the poem's many ironies, as it is essentially a new, highly original poem about the poet's inability to come up with new poetic themes. Ultimately, it is a complex and moving vision of an aging man reflecting on his life's work, and wondering it all means.