This book demonstrates the similarities within differences between Paul Tillich's (1886-1965) and Chu Hsi's (1130-1200) concepts of human condition. Tillich and Chu, one of the leading Christian theologians of the twentieth century and the greatest Sung Neo-Confucian philosopher respectively, were both profound students of human nature. By developing three vague comparative theological categories - unity, activity, and reunification - this book suggests that, although these two great thinkers came from two radically different religious traditions and cultures, Tillich and Chu articulated similar views of the unity of human reality and the problem of human existence. Furthermore, they proposed remarkably parallel strategies to resolve the tensions of finite human existence in searching for a reunification of human nature with its root in divine reality. Although these three comparative categories are generated from the fertile matrix of Tillich's thought they are designed to deal with a problem and its resolution common to Chu's thought as well.