While there are several significant themes in Things Fall Apart, such as individual alienation and loneliness, good and evil, clash between cultures, and custom versus tradition, one might say that the most significant is the theme of choice and consequence because it embraces the others. This theme is demonstrated from the early years of Okonkwo's life when he rejects his father's legacy and defeats the chi that links them together in the same pattern. It is still seen as the driving force in Okonkwo's life just before it ends after he decapitates a man.
Okonkwo's choice to challenge his early chi leads to the consequence of alienating and mistreating his son Nwoye and to being demanding of and unkind toward his wives. His choice to participate--against reason and against wise advice--in the ritualistic sacrificial death of Ikemefuna leads to the consequences of a completely shattered relationship with his son, a shattering which may be shown metaphorically in the descent of the locust:
Mighty tree branches broke away under them, and the whole country became the brown-earth color of the vast, hungry swarm.
There are many other instances of choices with potent consequences in Okonkwo's life but the ultimate choice with the most final consequences is his choice to fight against the missionaries and British officials. His choice to decapitate an official leads to a double consequence. The first consequence is that he learns his tribe has changed so deeply during his exile that they do not now stand behind his act of vengeance. The second consequence is that he sees that since his tribe has stood against him, he ironically has no choice left but to enact an ignoble and dishonorable end for himself, and so he takes his own life.
The white man is very clever. He came quietly and peaceably with his religion. We were amused at his foolishness and allowed him to stay. Now he has won our brothers, and our clan can no longer act like one. He has put a knife on the things that held us together and we have fallen apart.
In Things Fall Apart, Achebe is guided by two considerations i.e. to recreate the past of Africa and counter the European version of the african.
" Turning and turning in the widening gyrE
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold".
Yeat's philosophy can be traced in the fate of the imaginary but typical village of the lower niger in Achebe's novel " Things fall apart" that no civilisation can either remain static or evolve forever towards a more inclusive perfection. Achebe hoped to rewrite the past of his homeland from the inside of african mind so as to reveal and recover the african traditions and culture. Or one can say he is engaged in the revival of lost edenic african world and the lamentation of the fall of a great african hero. Achebe's work always include theme of Igbo dualism. UUmuofia is a typical Igbo world of dualities depicting the coexistence of the natural and supernatural worlds, of the Igbo religion and christanity, of individual and community, and of male and female principles. The theme of misrepresentation of the uncivilised barbarian african culture in colonial discourse is constantly challenged by Achebe. Therefore Achebe wanted to prove that " african history was not long might of savages".