Speaking truth to power has always been a high-risk strategy in China. Its rulers tend to prefer flattery, and writers who forget this do so at their peril. China's "grand historian" - 2,000 years ago - was one of many who have paid a terrible price.

"Among defilements, none is so great as castration. Any man who continues to live having suffered such a punishment is accounted as a nothing."

The man who wrote those words is by no means a nothing today. In a nation obsessed by its history, Sima Qian was the first and some say the greatest historian....