This week, George W. Bush, the US president, meets Hu Jintao, his Chinese counterpart, during the first US visit by a Chinese head of state since 1997. As the authors of an important recent study remark: “The US-China relationship is too big to disregard and too critical to misread”.* The two countries are fated to co-operate. The question is how best they can do so.

One could not imagine a worse-matched couple: the one a democracy, the other an autocracy; the one a child of the enlightenment, the other the avatar of the world’s most enduring agrarian empire. It will take an effort not just of imagination, but of will, for the two to work well together. Yet failure to do so could lead to another dismal epoch of disorder. The world must not let the opportunity for peaceful exchange and prosperity slip through its fingers, as it did so tragically in the first half of the twentieth century.