The novel takes its title from a verse in the poem “The Second Coming” by W. B. Yeats, an Irish poet, essayist, and dramatist:
Turning and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the center cannot hold;
Mere anarchy is loosed upon the world.
In this poem—ironically, a product of European thought—Yeats describes an apocalyptic vision in which the world collapses into anarchy because of an internal flaw in humanity. In Things Fall Apart, Achebe illustrates this vision by showing us what happened in the Igbo society of Nigeria at the time of its colonization by the British. Because of internal weaknesses within the native structure and the divided nature of Igbo society, the community of Umuofia in this novel is unable to withstand the tidal wave of foreign religion, commerce, technology, and government. In “The Second Coming,” Yeats evokes the anti-Christ leading an anarchic world to destruction. This ominous tone gradually emerges in Things Fall Apart as an intrusive religious presence and an insensitive government together cause the traditional Umuofian world to fall apart. (Cliffs Notes)
“The Second Coming” (Yeats 2106) has obvious Christian imagery. This is alluded to in the title of the poem. Other mythological or religious images exist, as in “The ceremony of innocence is drowned” (2107). This presents a similar idea to that of the killing of the innocents in Matthew 2:13-23. When “The Second Coming” (2106) is placed in its historical context (January, 1919), it could probably be presumed that the Great War influenced Yeats’ poem. The loss of innocence has two levels of influence: the death of innocent people in the war; and the impact this had on universal human consciousness (Yeats refers to this as “Spiritus Mundi” [2107] http://dlibrary.acu.edu.au/staffhome/migriffith/engl202/Fletcher_Timothy/essay.htm
"The Second Coming": Yeats had a vision of the cycles of history; each cycle lasted 2000 years. From 1 A.D., the year supposedly of the birth of Jesus of Nazareth, to 1919 has been the Christian era; towards the end of the millennium, as we approach the year 2000 (when another age will be born) the momentum of the present age slows, falters and "Things fall apart; the centre cannot hold." Yeats expresses his vision of the cycles of history through the image of the gyre, the cone-pattern of the falcon's flight: "Turning and turning in the widening gyre/ The falcon cannot hear the falconer." The momentum of the gyre and the cone pattern are rather like the movement of a spinning top: in the beginning, the motion of the top is stabilizing, but as it slows down the top begins to wobble, to destabilize; thus, in the last hundred years of the Christian cycle, the momentum is slowing and destabilization takes place. Yeats' best evidence of destabilization was the "blood-dimmed tide" of World War I. This poem was written several years after The Great War.