It has been through the peaceful victories of mercantile traffic, and not by the force of arms, that modern states have yielded to the supremacy of more successful nations.” Thus did Richard Cobden, 19th century proponent of unilateral free trade, warn his fellow countrymen that the rising prosperity of the US would soon sweep British global supremacy away.

Cobden wrote these words in the 1830s, long before the event. In this challenging new study, Arvind Subramaniam of the Peterson Institute for International Economics writes of the next transfer, that from the US to China. This one is surely closer. While Americans were prating of the “uni-polar moment”, its economic foundations were crumbling away. Properly measured, he argues, China is already its economic equal. Very soon it will be far more powerful, economically, and ultimately, also militarily.

This is a provocative thesis. Yet, since it has four times the population, China will surely eclipse the US, economically, in time. The question is rather how close that event now is.