Context

Taken from the first stanza of Yeats's "The Second Coming," this line is used to describe the falcon as it whirls steadily away from the falconer in a "widening gyre" (that's poem-speak for a circle).

Of course, as can be seen in the following lines, what falls apart isn't just human-avian communication, but really the whole world—as the "blood-dimmed tide is loosed." 

Well, that escalated quickly.

This poem is one of Yeats's most well-known, partly because of its extreme emotion and violent imagery and partly because of the density and complexity of its meaning. Most scholars (Shmoop included) can't agree on exactly what it means, but it definitely gets intense, what with the whole "rough beast" with the "pitiless gaze" as the messiah returns in the form of a pagan creature.

All this apocalyptic talk is probably a reaction to the Great War, which had just ended when the poem was published. The "centre that cannot hold" may be society's ties to religion or other traditional cultures or worldviews that have been rendered basically moot by the war. 

And "ceremony of innocence" being drowned? We miss the disobedient falcon already.

Where you've heard it

The first half of this quote should sound familiar: it's the title of a super famous Chinua Achebe novel. 

It's no coincidence, of course: Achebe got the title from Yeats's poem, and the first three lines of the poem are the novel's epigraph.

Pretentious Factor

If you were to drop this quote at a dinner party, would you get an in-unison "awww" or would everyone roll their eyes and never invite you back? Here it is, on a scale of 1-10.

As long as you don't get carried away and talk about Yeats's philosophy of Spiritus Mundi, it'll just seem like you're describing a poorly made wedding cake.