 There is no denying that, even for Tasan, Vital Force is what is responsible for individuality in the world. But he flatly rejects the view that this Vital Force is ultimately derived from Principle. In particular, he rejects the classical view of Supreme Ultimate (C. Taiji) according to which all is derived from the polarity of yin and yang. What then could be the ultimate source of being in the world? In order to answer this question, we now have to turn to Tasan’s view of Heaven. For Tasan, “Heaven” typically means the absolute personal being. In this regard, he frequently calls it “Lord on High (sangje C. shangdi)”. Supreme Ultimate surely is the beginning process of the world that is governed by Lord on High, but the former is not itself the dynamic principle and the origin of all things. Indeed, Lord on High is a personal God who is the governor of the universe and the source of its moral order (Lectures on Zhongyong in The Complete Works of Yŏyudang Chŏng Yagyong I, 8:30; Self-Admonition on Zhongyong in The Complete Works of Yŏyudang Chŏng Yagyong II, 3:5). Lord on High is also providential, i.e., he cares for his creatures. It is now clear that Tasan rejects the orthodox conception of Principle or Supreme Ultimate as the ultimate ground of morality because an impersonal principle cannot justify morality. Supreme Ultimate as the metaphysical principle cannot provide any mechanism for praise or blame. In other words, given the orthodox view of Principle, it is not clear how the morally depraved would be sanctioned while the morally virtuous would be rewarded in the mechanistic, impersonal scheme of orthodox Supreme Ultimate. In being the ruler and providential power of the world, Lord on High is clearly different from the myriad creatures. For this reason, Tasan regards Lord on High as the spiritual being par excellence, i.e., kwisin (C. guishen). For this reason spiritual beings are the invisible entities that ought to be the objects of worship in sacrificial rites (H. Kim 2019b).