 One of the most important conceptual and ontological frameworks found in Korean Neo-Confucianism is the paired concepts of Essence (ch’e) and Function (yong.) As in the Buddhist tradition, the Essence-Function structure permeates the entire view of reality among Korean Neo-Confucians when they connect the inner structure of phenomena with its external expressions. Thus, for those Neo-Confucians, all things, processes, and complexes in the universe can be considered in terms of two aspects, i.e., Essence and Function. Just as in Buddhism, “Essence” refers to the underlying structure of something that provides the ground or pattern for its activities or changes within the world. “Function” then refers to what is manifested by what is hidden or invisible. Neo-Confucians applied the Essence-Function paradigm to the most important parts of their philosophical edifice, i.e., cosmology, moral psychology, the process of self-cultivation in sage learning, etc. It is important to keep in mind that “Essence (ch’e 體)”, which literally means “body”, does not refer to a reified entity, as in the Western metaphysical concept of substance. “Essence” and “Function” refer to two different ways or aspects of what is fundamentally one and the same. In this sense, the Essence of something is not separate from its Function. They mutually embrace each other in a seamless way. But there is definitely an order or hierarchy between them. Essence is always thought to take precedence over Function. In this sense, it is prior to, or more fundamental than, Function. Neo-Confucianism, for example, repeatedly emphasizes that human nature (sŏng 性) in its unaroused state (mibal 未發), i.e., before entering into the realm of activity, is the Essence, and the feelings expressed in everyday life are its Function. In this context, “Essence” refers to the heart/mind of the sage (sometimes called “tosim (C. daoxin, the heart/mind of the Dao)”, and Function to the behavior of an ordinary person or insim (C. renxin, the heart/mind of an ordinary person). The idea then is that what is underlying as a fundamental principle can be pulled in all directions in the manifest world. There is no doubt that this Essence-Function paradigm is importantly related to what is known as “Correlative Thinking”, according to which the world is an interconnected web where everything or every phenomenon is situated in a dynamic cycle of relations both productive and anti-productive to some others (Needham 1954).