Shakespeare’s Julius Caesar wanted to have men about him who were fat because lean and hungry men were dangerous. If the same principle applies in international relations, this week’s news that China has overtaken the world’s second-largest economy, Japan, in terms of nominal gross domestic product should be welcome to the rest of the world. Yet nominal GDP is unfortunately a poor guide to what constitutes a satisfied, unthreatening state. Per capita income is a better, if imperfect, pointer. And since China’s per capita income of $3,678 is still less than a 10th of Japan’s, Caesar would have drawn little comfort from this watershed, given that China clearly remains a very poor country despite its spectacular recent growth rate.