Turning and turning in a widening gyre."
-- Speaker (Line 1)

Importance: The "gyre" is one of the most iconic images from the poem. It represents the entire world, ever-growing and expanding. It is also an image which depicts the world as unstable and transitory. A spiral motion, the gyre moves out from an undefinable starting point in a non-linear fashion. This image establishes the poem's theory of history as moving towards to chaos, rather than moving progressively towards an endpoint.

The Falcon cannot hear the falconer.
-- Speaker (Line 2)

Importance: This line signals the breakdown in meaning and communication within the chaotic historical epoch. The falcon who is guided by the falconer can no longer "hear," as it is sucked into the vortex of time. The fact that Yeats specifically chooses a falcon and falconer is also relevant, as this suggests a breakdown of meaning not only within humanity, but between humanity and nature.

Things fall apart; the...
-- Speaker (Line 3)