Yi I (Yulgok) and the Critique of Toegye's Dualism

Yi I (1536-1584), known by his pen name Yulgok ("chestnut valley"), was born in Gangneung and, according to widely repeated biographical tradition, was raised largely by his mother, the painter and poet Sin Saimdang (1504-1551), herself later celebrated as a model of Confucian female virtue and, in the 21st century, commemorated on the South Korean 50,000-won banknote. Yulgok passed nine separate civil service examinations at the top rank, an unusual feat that earned him the nickname "Nine-Time Excellence" (Gudojanggwon), and served in senior court posts including minister of personnel and minister of war before his early death at forty-eight. His major writings include the Seonghak jibyo (Essentials of Sage Learning, 1575), compiled as a further guide for royal education, and his own correspondence with Seong Hon (Ugye, 1535-1598) conducted between 1572 and 1578, which forms the second major documentary strand of the Four-Seven Debate, distinct from but directly responsive to the earlier Toegye-Gobong exchange.