William Butler Yeats (1865-1939) is the greatest poet in the history of Ireland as well as widely acknowledged as one of the greatest English-language poets of the 20th century. His themes, images, symbols, metaphors and poetic sensibilities encompass the breath of his personal experience, as well as his nation’s experience during one of the most troubled times.
Yeasts’ great poetic project was to reify his own life-his thoughts, feelings, speculations, conclusions, dreams-into poetry: to render all of himself into art, but not in a merely confessional or autobiographical manner; he was not interested in the common-place. He was a key figure in the Irish Cultural Revival, his later poems made a significant contribution to Modernism, and he was awarded the Noble Prize for Literature in 1923.
Yeats wrote The Second Coming while Europe and much of the rest of the world was trying to recover from World War I. This was surely an important factor for him in writing the poem. Yeats saw great social troubles all around him, and remarks on a world spinning out of control.
Yeats starts out with the image of a falcon wheeling about in the sky, far away from the falconer who released it. The bird continues to wheel and gyre further and further away from the falconer. This metaphor stands for the young people who have given up the standards of their parents and grandparents for the new art, the new literature, the new music, and the other novelties of Yeats' time.
Line 2 hints at technology progressing beyond mankind's ability to control it. The problem was evident to Yeats 80 years ago, and the problem has worsened since then. Yeats shows his concern that technology has advanced to the point where mankind can do a great deal of harm with relative ease. The world had never seen destruction of the likes of World War I, and most people were shocked at the extensive loss of human life during the war.
The last two lines of the first stanza are simply a commentary on the times. Yeats says "The best lack all conviction, while the worst are full of passionate intensity." This also suggests dissociation between the best, which Yeats identifies as head people, the intellectuals, and the worst, which Yeats associates with the mob who are those who react with passionate intensity not with careful intellectual study and expression.
At the start of the second stanza Yeats calls for a revelation, saying "Surely some revelation is at hand." And Yeats himself becomes the revelator. Yeats is a revelator because he gives us a powerful image for The Second Coming. This is the image of a "rough beast" which has the head-intellect of a man and the fierce emotions and body intelligence of a beast.
Furthermore, Yeats suggests that the body movement of the beast, the "slouching" movement is what is moving the Christ closer and closer to its "Bethlehem" or birthplace. Yeats adds the image of the head-intellect connected to the body-mind of a beast to the image Isaiah gave as a little child for The Messiah. This makes Yeats a modern revelator or prophet.
It's significant that Yeats describes the Sphinx as "A gaze blank and pitiless as the sun," because spiritual masters are known to gaze blankly as they transmit "the message" to their disciples. Yeats equates this gaze and this transmission with the Sphinx, which he also uses to denote the Second Coming of Christ.
After Yeats presents this brilliant visionary image, he says “The darkness drops again." His vision ends and he starts thinking again. He concludes that "twenty centuries of stony sleep were vexed to nightmare by a rocking cradle." This is a puzzling line, because the rocking cradle suggests the manger where Jesus was laid. But a manger doesn't rock unless some animals are jostling it about in their movements. And this again suggests that animal body movement figures strongly into this idea of Christ which Yeats presents in this poem.
This poem is a riddle. Yeats ends by asking a question. Throughout the poem there are hints as to what the answer to the riddle is. But Yeats doesn't come right out and give the answer to the riddle. Yeats uses the image of a cat, i.e., the Sphinx in juxtaposition with the two images of birds. First Yeats presents the broken image of the falcon dissociating from its trainer and master the falconer. Then Yeats presents the broken image of many birds flying around the Sphinx.
But the cat itself is a single whole image. Furthermore, the cat eats birds. The cat is mightier than the birds. The idea of being mighty is amplified by the very size of the Sphinx. This suggests the power of the process which integrates the human intellect with the animal power of the bodily intelligence of the animal beast. However this idea rather conflicts with the conventional Christian idea that Christ overcomes the Beast of Revelation. So Yeats is challenging certain images in conventional Christianity.