Korea, Neo-Confucian philosophy in

Yi Hwang (Toegye, 1501–1570), Yi I (Yulgok, 1536–1584), and Jeong Yagyong (Dasan, 1762–1836) were the three most eminent Neo-Confucians in Korea. Toegye strongly influenced Korean Neo-Confucianism ( seongnihak ) by articulating the "sagely learning" that must integrate knowledge, moral practice, and spiritual cultivation. His "Four-seven debate letters" also enrich the moral-spiritual dimension of Neo-Confucianism by emphasizing principle ( i ), mind cultivation, and reverence. Yulgok advocated political, economic, and social improvement by addressing the fundamentals of ethics and statecraft. His "Four-seven" philosophy presents a systematic interpretation of human nature, emotions, and self-cultivation by highlighting the idea of material force ( gi ). Dasan, the most famous Silhak (practical learning) thinker, criticized Seongnihak orthodoxy and defined the silhak in terms of promoting people's daily lives. He charged that the metaphysics of principle and material force is not based on the original classics; the unifying thread of Neo-Confucianism is the inseparable link between personal cultivation and public service.