Zhū Dānxī 朱丹溪 (real name 朱震亨 Zhū Zhènhēng, zì Yànxiū 彥修, hào Dānxī 丹溪, 1281–1358), Yuán-period physician of Yìwū 義烏 (Zhèjiāng) and one of the Jīn-Yuán sì dàjiā 金元四大家. Founder of the Zīyīn pài 滋陰派 (Nourishing-Yīn School). Principal works: Géhì yúlùn 格致餘論, Júfāng fāhuī 局方發揮, Jīnguì gōuxuán 金匱鈎玄. His doctrine “yáng often surplus, yīn often insufficient” became foundational for late-imperial gynecological and zábìng therapeutics.