CHŎNG YAGYONG (1762–1836), foremost representative of Korea's Sirhak (Practical Learning) movement and creator of a theistic Confucian philosophy. He is best known by his honorific name, Tasan. The Sirhak movement was characterized by a spirit of seeking evidence to establish fact, as opposed to more speculative modes of thought, and a spirit of practicality as seen in studies concerned with administrative and economic reform. Contemporary Koreans look to Sirhak as a kind of indigenous proto-modernity within their own tradition, although the movement seems to have largely dissolved by the second half of the nineteenth century. Tasan is especially revered as the preeminent intellectual figure of the movement, a polymath who mastered the principles of Western mechanics to build a town wall, wrote insightful treatises on government and social reform, and in his many works passed in critical review some two...