The man who began a cultural awakening in China which led ultimately to the Tiananmen Square student protest in 1989 has died in exile in the U.S.
Fang Lizhi and his wife played no public role in the protests themselves but sought refuge in the American Embassy after pro-government supporters burned effigies of him.
Once China's leading astrophysicist, Fang and his wife hid in the US Embassy for 13 months before leaving China - he never returned.
In 1986, Fang had emerged as an eloquent advocate of radical political change in China, declaring science should not be determined by Marxist theory.
He was quoted as saying in 1987 that the Chinese Communist Party could not boast of a single success in nearly 40 years of rule. "Marxism...is like a worn dress that must be put aside," he said.
His constant challenge to the Party apparently incurred the wrath of China's leader of the time, Deng Xiaoping. In a secret speech to central committee members in 1987, Deng singled him out by name for expulsion from the Party.
However he would not be silenced and continued to receive letters of support from across the country almost daily.
Fang's friend and fellow US-based exile Wang Dan has said:
Fang Lizhi died in Tucson, Arizona of natural causes, he was 76.