The falcon cannot hear the falconer; things fall apart; the center cannot hold. Yeats wrote this in the aftermath of World War I, and the rough beast slouching toward Bethlehem has become one of poetry's most quoted images. The poem prophesies an apocalyptic transformation, a new annunciation as violent as the first. The gyres of history turn; the two thousand years of Christianity end. Yeats believed in cycles; the poem enacts the vertigo of historical change. The best lack all conviction; the worst are full of passionate intensity. The beast arrives. It is always arriving.