The West once ruled more than half the world. The religion it exported, Christianity, is still followed by a third of mankind. Above all, the way people live, or aspire to live, are unmistakably an invention of the West. All over the world, more and more humans eat a Western diet, wear Western clothes and live in Western housing. Niall Ferguson explains how by juxtaposing, we can uncover the keys, the six killer applications, of Western ascendancy.