London's Tate Modern gallery has purchased an artwork made up of eight million porcelain images of sunflower seeds. Even by the standards of contemporary art this work will seem puzzling, not to say ridiculous - until you know the back story.
The artist, Ai Weiwei, is contemporary China's most prominent dissident. An international reputation has protected him only partly from the consequences of his complaints about China's human rights failures and about the corrupt, shoddy school construction which killed so many children in Sichuan's 2008 earthquake.
He spent 81 days in detention last year on suspicion of ill-defined "economic crimes", and was freed under onerous conditions. But at least he was released; many others remain prisoners of conscience. His studio near Shanghai was abruptly demolished by official order last year.
Art has power. The sunflower seeds refer to Maoist propaganda: Mao Zedong as the sun, and the people as seeds on sunflowers turning to him; a bitter image now that the world knows of Mao's crimes. For making such statements Mr Ai was listed atop Art Review magazine's 2011 list of the art world's most powerful people, among other honours.
But it is the Chinese government that has the real power, so much of it that a Chinese citizen's criticism of the regime's foul record must be oblique, paraphrased through art, and displayed 9,000km from home.
