The earliest extant text that contains a list of items arranged according to their yin and yang qualities is a manuscript found in Mawangdui entitled Designations ( Cheng ), likely dating from the third century b.c.e. Scholars generally deem that the terms yin and yang originally denoted the shaded and sunny sides of a hill and later began to be used in an abstract sense as cosmological categories. The origins of these notions are impossible to ascertain. This mode of operation is especially visible in the time cycles of the day (alternation of daytime and nighttime) and of the year (alternation of the four seasons). When one of the two principles prevails, the other yields, but once one of them has reached the height of its development, it begins to recede in that very moment, the other principle begins its ascent. At the same time, the phrase 'one yin and one yang, this is the Dao' refers to the continuous alternation of yin and yang within the cosmos. As each of these stages generates the next one, yin and yang are ultimately contained within the Dao itself. Their repeated alternation provides the energy necessary for the cosmos to sustain itself, and their continuous joining and separation is at the origin of the rise and the disappearance of the entities and phenomena that exist within the world of the 'ten thousand things' ( wanwu ).Īccording to a celebrated statement, which is found in one of the appendixes to the Book of Changes ( Yijing ), 'one yin and one yang, this is the Dao.' This sentence refers to the Dao that first determines itself as the One (or Oneness) and then through the One gives birth to the two complementary principles. In Chinese cosmology, yin and yang are two opposite but complementary principles that regulate the functioning of the cosmos.

Yin and yang