Li () is a classical Chinese word which is commonly used in Chinese philosophy, particularly within Confucianism. Li does not encompass a definitive object but rather a somewhat abstract idea and, as such, is translated in a number of different ways. Wing-tsit Chan explains that li originally meant "a religious sacrifice, but has come to mean ceremony, ritual, decorum, rules of propriety, good form, good custom, etc., and has even been equated with natural law." In Chinese cosmology, human agency participates in the ordering of the universe by Li ('rites'). There are several Chinese definitions of a rite. One of the most common definitions is that it transforms the invisible to visible; through the performance of rites at appropriate occasions, humans make visible the underlying order. Performing the correct ritual focuses, links, orders, and moves the social, which is the human realm, in correspondence with the terrestrial and celestial realms to keep all three in harmony. This procedure has been described as centering, which used to be the duty of the Son of Tian, the emperor. But it was also done by all those who conducted state, ancestral, and life-cycle rites and, in another way, by Daoists who conducted the rites of local gods as a centering of the forces of exemplary history, of liturgical service, of the correct conduct of human relations, and of the arts of divination such as the earliest of all Chinese classics—the Book of Changes (Yi Jing)—joining textual learning to bodily practices for health and the harmonized enhancement of circuits of energy (qi). Scope The rites of li are not rites in the Western conception of religious custom. Rather, li embodies the entire spectrum of interaction with humans, nature, and even material objects. Confucius includes in his discussions of li such diverse topics as learning, tea drinking, titles, mourning, and governance. Xunzi cites "songs and laughter, weeping and lamentation...rice and millet, fish and meat...the wearing of ceremonial caps, embroidered robes, and patterned silks, or of fasting clothes and mourning clothes...unspacious rooms and very nonsecluded halls, hard mats, seats and flooring" as vital parts of the fabric of li. Approaches to Li Among the earliest historical discussions on li occurred in the 25th year of Duke Zhao of Lu () (517 BCE) in the Zuo Zhuan. Li consists of the norms of proper social behavior as taught to others by fathers, village elders and government officials.