Zhang Congzheng (Chinese: 張從正; pinyin: Zhāng Cóngzhèng; 1156–1228),[1] courtesy name Zihe (Chinese: 子和; pinyin: Zihé),[2] was a Chinese physician and writer active during the Jin dynasty. Based in the capital city of Daliang (大梁; present-day Kaifeng, Henan), Zhang was known for his aggressive and unorthodox approach to medicine, which was based on the belief that all illnesses were caused by "deviant" qi.[1] He is regarded as one of the "Four Great Masters" of the Jin-Yuan period.