He was nicknamed "the steel mill" for his capacity to just keep going on and on. He was Mao's lieutenant who was purged twice and rose three times, the final time to the very top. He enabled China's economic miracle to happen after 1978 by allowing capitalism to reemerge in the world's biggest Communist country. "It doesn't matter if a cat is white or yellow if it catches mice," he observed. He put down protests with ferocity in 1989. And he negotiated the last piece of unfinished business between Britain and China - the return of Hong Kong in 1997. As China becomes ever more prominent today, we need to understand that we live in Deng Xiaoping's world - and why.