David Cameron's visit to China raises a troublesome moral challenge. In the next one hundred years it is likely that China will be one of the most powerful countries on earth.
It could easily vie with India as the global superpower leaving the United States but also the United Kingdom behind. Assuming all goes well for its economy it could easily be the richest country in the world by the middle of the 21st century and with that wealth will come power, military as well as diplomatic.
As a statesman the Prime Minister has to deal with this reality. However, China also remains a despotism without the rule of law, free speech, freedom of religion or protection from arbitrary arrest.
Any contrary spirit is crushed so the Dalai Lama lives in exile, Catholic priests are in prison and the Nobel Peace Prize winner, Liu Xiaobo, languishes in a Chinese gaol.
China, not surprisingly, does not welcome interference in its affairs and is highly sensitive to criticism. This risks making things worse by discussing human rights but not doing so looks weak as if preparing to kowtow.
Ultimately, the question is: will rising living standards lead to a natural demand for political rights and therefore, will helping China prosper speed up freedom or will the Communist government believe that if it is accepted by the west it need not change.
In my view the fundamental worry is with Communism, not with the history of China. As it loses its remaining semblance of ideological underpinning so it is likely that China's politics will change. This justifies engagement buy not yet friendship.