Chou Tun-yi (1017–73), Chinese Neo-Confucian philosopher. His most important work, the T’aichi t’u-shuo (‘Explanations of the Diagram of the Supreme Ultimate’), consists of a chart, depicting the constituents, structure, and evolutionary process of the cosmos, along with an explanatory commentary. This work, together with his T’ungshu (‘Penetrating the I-Ching’), introduced many of the fundamental ideas of Neo-Confucian metaphysics. Consequently, heated debates arose concerning Chou’s diagram, some claiming it described the universe as arising out of wu (non-being) and thus was inspired by and supported Taoism. Chou’s primary interest was always cosmological; he never systematically related his metaphysics to ethical concerns. See also T’AI-CHI. P.J.I.