Essence-Function

Essence-Function (體用, Chinese pinyin: tǐ yòng, Korean: che-yong), also called Substance and Function, is a key concept in Chinese philosophy and other Far-Eastern philosophies. Essence is Absolute Reality, the fundamental "cause" or origin, while Function is relative or concrete reality, the concrete manifestation of Essence.

Together they form the phrase 體用 ti-yong, 체용 che-yong, Essence-Function.

Essence is Absolute Reality, the fundamental "cause" or origin, while Function is manifest or relative reality, the discernible effects or manifestations of Essence.Essence-Function describes the interplay between the two: although Absolute Reality is the ultimate reality, the relative reality nevertheless also exists, as is evident from concrete reality. The relationship between these two realms is espressed in such schemata as the Five Ranks and the Oxherding Pictures. Various terms are used for "absolute" and "relative".

The tree forms a metaphor for Essence-Function, with the roots being Essence and the branches being Function. According to Muller "the most important application of t'i-yung thought [...] is to the human being, where the human mind is seen as "essence," and one's words, thoughts and actions are seen as "function."

According to Sung-bae Park the concept of essence-function is used by East Asian Buddhists "to show a non-dualistic and non-discriminate nature in their enlightenment experience," but does not exclude notions of subjectivity and objectivity. According to Sung-bae Park, the terms "essence" and "function" can also be rendered as "body" and "the body's functions," which is a more personal and less abstract expression of nonduality.

The t'i-yung developed in the Wei (220–265) - Chin (265–420) period of Chinese history, when "Unification of the Three Teachings" ideology was domimant, striving for a theoretical reconciliation of Confucianism, Daoism, and Buddhism. The t'i-yung concept was first known as pen-mo ("primary-last" or "primary-subordinate"), and developed into t'i-yung. In the initial development of the theory, "thinkers considered one of the three philosophies as 'the primary' or 't'i' and the others as 'the last' or 'yung,' insisting that their own philosophy was superior to the others." However, although the theory was used to arrange the three teachings hierarchically, it also confirmed their inner unity.

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