Surely some revelation is at hand; Surely the Second Coming is at hand.
Notice how these two lines are almost exactly the same. This is where the speaker tells us what he thinks is going on, but the repetition means that he’s maybe not so sure and is slowly trying to figure things out.
It’s a revelation, he says, which is when the true meaning of something is revealed.
Not only that, but it’s a revelation according to the most reputable source for these kinds of things: the Book of Revelation.
Apparently, all this violence and moral confusion means "the Second Coming is at hand." According to the Bible, that means Christ is going come back and set everything straight, right?
We’ll see. For now, the poem is about to take another turn.
The Second Coming! Hardly are those words out When a vast image out of Spiritus Mundi Troubles my sight: somewhere in sands of the desert
So maybe we’re not saved.
The words "Second Coming" seem to have made the speaker think of something else, so that he repeats the phrase as an exclamation. It’s like, "Eureka!" It makes him think of a "vast image out of Spiritus Mundi."
To know what this means, you have to know that Yeats was very interested in the occult and believed that people have a supernatural connection to one another. It’s in the same ballpark as telepathy or a psychic connection, but not quite as kooky as those other things. It’s more like we’re all connected to a big database of communal memories going back all the way through human history, which we can get in contact with when we’re feeling truly inspired.
Literally, Spiritus Mundi means "spirit of the world."
The speaker, through his sudden, revelatory connection to the world, is given access to a vision that takes him "somewhere in the sands of the desert."
A shape with lion body and the head of a man,
Here, he is describing the sphinx, a mythical beast "with lion body and the head of a man."
You might have seen the picture of the ancient sphinx in Egypt: it’s pretty famous. But Yeats isn’t talking about that sphinx, per se. He’s talking about the original, archetypal symbol of the sphinx that first inspired the Egyptians to build that big thing in the desert, and which is now inspiring him.
A gaze blank and pitiless as the sun, Is moving its slow thighs, while all about it Reel shadows of the indignant desert birds.
In these lines he describes the sphinx’s expression and what it is doing.
By calling its gaze "pitiless," he doesn’t mean "evil" or "mean-spirited." In fact, the sphinx really seems to have an inhuman expression that is as indifferent as nature itself. It is "blank," statuesque, and incapable of having empathy with other humans.
This might not tell us much, but now we know that the sphinx doesn’t jibe at all with the way most people think of Christ. In other words, this "Second Coming" doesn’t seem to have at lot in common with the descent of Christ from Heaven as described in the Book of Revelation.
Nor does it seem to be in any big hurry to get here, as it moves "its slow thighs."
But, strangely, this slowness only seems to add to the suspense and terror, like Michael Myers chasing Jamie Lee Curtis in the movie Halloween.
Even the birds are ticked-off, or "indignant," but it’s not clear why. Their circling is similar to the gyres of the falcon from the beginning of the poem, but from what we know about desert birds, like vultures, when they fly in circles it’s often because they think something will die soon.
The darkness drops again; but now I know That twenty centuries of stony sleep Were vexed to nightmare by a rocking cradle,
The vision from Spiritus Mundi ends as "darkness drops again," like a stage curtain, but it has left the speaker with a strong prophetic impression. He knows something that he didn’t before, namely, that this strange sphinx is a symbol that will bear on the future.
Thinking outside the poem, it’s safe to say that he is talking about Europe’s future, and perhaps the world’s in general.
What exactly does the speaker claim to "know"? "Twenty centuries" refers to roughly the amount of time that has passed since the "first coming" of Christ. But we have already seen that the Second Coming is not going to be anything like the first.
Although 2,000 years seems like a long time to us, Yeats compares it to a single night of an infant’s sleep, which is suddenly "vexed to nightmare by a rocking cradle."
The cradle reinforces the image that something has recently been "born," and its motion also serves as a metaphor for social upheaval.
It’s interesting that the infant doesn't wake up because of the rocking. It instead begins to have nightmares, much like the recent nightmares afflicting European society, whose long history amounts to no more than the first stages of childhood. It’s the terrible two’s of an entire continent.
And what rough beast, its hour come round at last, Slouches towards Bethlehem to be born?
The object of Yeats’s vision, which was formerly symbolized as a pitiless sphinx, is now described as a "rough beast" on its way to Bethlehem – the birthplace of Christ – "to be born."
The "slouching" of this beast is animalistic and similar to the slow gait of the sphinx in the desert. It sounds more than a little menacing.
Yeats is using the birth at Bethlehem as a metaphor of the passage of this malevolent beast from the spirit world – Spiritus Mundi – to the real, everyday world, where its effects will be visible to everyone.
By phrasing these lines as a question, Yeats tantalizes us with all the possibilities of what he might be describing. In the time since Yeats wrote the poem, the beast has been interpreted as a prediction of everything bad that the twentieth century has wrought, particularly the horrors of World War II: Hitler, fascism, and the atomic bomb.
It is the "nightmare" from which society would not be able to awake. Of course, Yeats would not have known about these specific things. However, he did seem to have a sense that things were still getting worse while most people around him thought things were getting better.
Some readers have thought that the birth at the end was an ironic vision of the Antichrist, an embodiment of evil as powerful as Christ was an embodiment of goodness.
Others believe that the beast, even though it is described as "rough," might not be evil, but merely a manifestation of the kind of harsh justice that society as a whole deserves. In other words, things have become so violent and decadent that God’s only solution is to deploy his all-purpose cleanser.