Cheng Guonan, a student of geology, returned to his hometown in Yulin, in the Guangxi Zhuang autonomous region, in 1975 and now dedicates himself to looking for water for the local people. Photos by Huo Yan / China Daily

People think he's crazy. But for his part, Cheng Guonan thinks it's the world that's crazy.

"We cannot understand him sometimes. He lives life as an ascetic monk and dedicates his life to other people," says one of his neighbors.

Born into a farmer's family in 1934 in a mountain village in Yulin, in the Guangxi Zhuang autonomous region, Chen studied geology at the Beijing-based China University of Geosciences for five years. After graduation, he was assigned to the geological inspection bureau in Jinan, Shandong province, in 1963. It was a posting that was to change his life.

After four years, he became a chief engineer at the bureau and was in charge of searching for some key minerals for China's national defense industry.

However, during the "cultural revolution" (1966-76), the Red Guards accused him of using his field research as a way of spying for China's enemies and persecuted him as "a reactionary academic authority".

"They beat me with leather army belts and locked me up for days without giving me anything to eat," Chen recalls. "I was strong enough to see the end of the torture, because I was confident common sense would return one day. But some of my colleagues passed away."