China’s Achilles heel

LIKE the hero of “The Iliad”, China can seem invincible. In 2010 it overtook America in terms of manufactured output, energy use and car sales. Its military spending has been growing in nominal terms by an average of 16% each year for the past 20 years. According to the IMF, China will overtake America as the world's largest economy (at purchasing-power parity) in 2017. But when Thetis, Achilles's mother, dipped her baby in the river Styx to give him the gift of invulnerability, she had to hold him somewhere. Alongside the other many problems it faces, China too has its deadly point of unseen weakness: demography.