yin yang, metaphors used in the classical tradition of Chinese philosophy to express contrast and difference. Originally they designated the shady side and the sunny side of a hill, and gradually came to suggest the way in which one thing ‘overshadows’ another in some particular aspect of their relationship. Yin and yang are not ‘principles’ or ‘essences’ that help classify things; rather, they are ad hoc explanatory categories that report on relationships and interactions among immediate concrete things of the world. Yin and yang always describe the relationships that are constitutive of unique particulars, and provide a vocabulary for ‘reading’ the distinctions that obtain among them. The complementary nature of the opposition captured in this pairing expresses the mutuality, interdependence, diversity, and creative efficacy of the dynamic relationships that are deemed immanent in and valorize the world. The full range of difference in the world is deemed explicable through this pairing. See also CHINESE PHILOS- OPH. R.P.P. & R.T.A.