Anybody who read Things Fall Apart will recognize Isaac Okonkwo (called Nwoye before he converted to Christianity). As a young man, he left his father's house and became a Christian, severing his ties with his family and his heritage. As an older man, we see where that path has led him.
Isaac's love for the written word brings glory to his family when his son Obi proves to be brilliant and becomes the top pick to go to Great Britain for college. But despite his lifelong devotion to the church and his work as a catechist, Isaac Okonkwo has very little money in his old age, and he is dependent on his son. This doesn't make Isaac weak, however. He still has an opinion. And he surprises his son because, despite his adherence to Christianity and his love for the written word, there are parts of his culture heritage for he has great respect. He refuses to be convinced that Obi's engagement to Clara is a good idea. Using his patriarchal authority, he tells Obi simply that he cannot marry her.
And he does not budge. In our last glimpse of Isaac in this novel, he explains to Obi that he knows better than anyone what it means to be a Christian, and Obi cannot tell him that it is a Christian act to marry an osu. That reminder has a double importance, though. Isaac is also reminding his son that when he has decided something, when he has set his mind on a path, he does not give up. He is determined. Obi is either willfully blind, wishful, or simply lying when he tells Clara that his father will come around. The truth is, Isaac is just as stubborn now as he was the day he left his father's house and joined the Christians. His will is iron. He will not bend.