 In the late fourteenth century, Chŏng Tojŏn (鄭道傳 1342–1398), a Confucian literatus and philosopher, found it necessary to launch extensive criticisms of Korean Buddhism as he tried to help found the new Dynasty of Chosŏn in accordance with a Neo-Confucian vision. As he saw it, Korean Buddhism was hopelessly defective and corrupt in many ways. Most unfortunate of all, Chŏng argued, it was based on the concept of mu (無 Nothing) and thus necessarily led to nihilism, which undermined social morality and disrupted the political order (Chŏng, “An Array of Critiques of Buddhism” in Muller 2015, 54-81). This criticism is clearly far-fetched, as can be seen from the response (see below) of the Buddhist critic Hamhŏ Kihwa (涵虛己和 1376–1431), a contemporary of his. Nevertheless, it shows a remarkable insight on the part of Chŏng in regarding mu as the founding notion of Korean Buddhism whose philosophy is deeply rooted in the paradigm of emptiness (śūnyatā) as an expression of inter-dependent co-origination of things. What I call “mu” may have been referred to in many ways in the past, e.g., emptiness (kong 空 śūnyatā), vacuity (hŏ 虛) or “wuji” (無極 infinite supreme), etc., but, in this work, “mu” roughly refers to the original dynamic yet serene dimension that is not induced by anything ephemeral in the world. It is a self-originating source of the world. A part of an active process, it also forms the momentum of a limitless dialectical movement. Historically speaking, this paradigm has a distinctive structure that serves as the basic conceptual framework for all major Korean intellectual traditions.