Good fences make good neighbours. This is not just a saying but an inescapable truth of the human condition. When the Berlin Wall was brought down, the idea of enforced separation was dismissed as something from the past. In practice, however, it is the exact opposite. Divided: Why We're Living in an Age of Walls by Tim Marshall explores how societies have responded to the changes brought by globalization and how each nation tries to maintain a sense of national identity.