City as Opportunity
Throughout No Longer at Ease there is a strong distinction made between the city and the village which manifests itself in many ways, sometimes less obvious than physical space. The city is viewed by the villagers (and indeed by the city dwellers, when they take the time to consider it) as a place of luxury and wealth. Obi is first struck by its brightness and its pace. The true association, on a deeper level, is one of opportunity. Cities, particularly those in Europe or with a European influence, are places to advance in status and knowledge. One can only go so far if he stays in the village but the city offers almost limitless experience.
Achebe emphasizes this by flashing back to Obi's departure and later bringing him back to his village after he receives his degree. Before Obi leaves, he is an especially talented villager, but he is still very much a member of the community. He himself doesn't know what to expect in England or even the city within Nigeria. In fact, he relies on descriptions of the experiences of others to anticipate a Nigerian city. Later when he makes his grand homecoming, he is not even capable of communicating to his neighbors the things he has seen and learned while in Europe. The villagers sent Obi to England so that he might be educated and successful but they aren't capable of ascertaining exactly what they gave him. In their minds, it is enough to know that he has been given opportunity.
Achebe makes it clear that there is a cost for such an opportunity. Although the city represents material success, the village is the center of traditional values. When Obi leaves, he loses not only some of his religion but some of his resolve. It is easy to argue, I think, that had he never left the village he never would have reduced himself to taking bribes. The village offers a system of support in maintaining values whereas the city accosts Obi with nonstop pressures making it increasingly difficult to stay virtuous. The villagers made the mistake of sending Obi to be a villager in the city without realizing that such a thing is impossible. His education and his surroundings changed him in a way that they could not understand. The city provides many useful things, but it is the village that provides the values in order to use the opportunity of the city properly.