In Achebe's 1958 novel Things Fall Apart, Achebe illustrates Ibo tribal life in the 1880s before missionaries and colonization have invaded the tribes. He shows the moral law and spiritual regulation operating within the Ibo culture and illustrates the very Kantian philosophy at work in Ibo culture requiring the betterment of one's self and circumstances while also bettering your fellow kind, the converse of the Western (unconscious?) motivation of self-betterment at others' expense. Achebe also uncovers the rich Ibo history of legends, myths, and stories, a complement to their deep and broad spiritual and moral principles.
The main character Okonkwo is a man who is highly respected and admired by his tribe despite the fact of his viloent temper; tendency to control his family through violence, which opposes Ibo principles; and mediocre chi, which seems to limit him from greatness regardless of his hard work, and he does work hard to overcome this prediction of mediocrity that escapes greatness. In consonance with his chi, Okonkwo commits a fateful sin and is exiled to the female realm of his mother's village for seven years.
Okonkwo returns to his own village at the end of that time to find a new religion, new authority in power, and a division in his tribe. The division, the accusations and recriminations, the violations to tribal custom of punishment, the intrusion of an outside authority with humiliating judgement and punishment tactics all stand in stark contrast to the picture so carefully drawn in Part I and so aptly revealed in Okonkwo's life. Achebe shows how colonization and Christianization--ignorantly and mistakenly imposed--shattered, in a decade, the rich fabric of a culture previously working for one another from deeply rooted and complex principles of moral and spiritual rectitude and left it rent, frayed, and unable to support the existence of the Ibo, some of whom had become counterfeit Westerners, having the form but not the substance of a Western philosophy that advanced power instead of unity, self-interest instead of unified interest.