1952- 19557- 1957- 2ndcent 580-643 active2ndcentury alchemy boyang china chinapoliticsweichengbiographies economicconditions economics economists history interviews jie jinshi894 liu pengrong religiousaspects sources taoism teh weicheng zheng zhong zhuang 刘伟 钟朋荣 韋莊 魏杰