The argument is that (1) the spiritual crisis that Zhu Xi discussed with Zhang Shi 張栻 (1133–1180) and the other “gentlemen of Hunan” from about 1167 to 1169, which was resolved by an understanding of what we might call the interpenetration of the mind’s stillness and activity (dong-jing 動靜) or equilibrium and harmony (zhong-he 中和), (2) led directly to his realization that Zhou Dunyi’s thought provided a cosmological basis for that resolution, and (3) this in turn led Zhu Xi to (...) understand (or construct) the meaning of taiji in terms of the polarity of yin and yang; i.e. the Supreme Polarity as the most fundamental ordering principle (li 理). (shrink)