Yin and yang viewed as parts of an oneness that is expressed in the Tao. The term "dualistic-monism" or dialectical monism has been coined in an attempt to express this fruitful paradox of simultaneous unity and duality. Yin and yang can be thought of as complementary (rather than opposing) forces that interact to form a dynamic system in which the whole is greater than the assembled parts. According to this philosophy, everything has both yin and yang aspects (for instance, shadow cannot exist without light). Either of the two major aspects may manifest more strongly in a particular object, depending on the criterion
Yin and yang Yin Yang Jia (Yin and Yang School) Needham concludes "There can be very little doubt that the philosophical use of the terms began about the beginning of the -4th century, and that the passages in older texts which mention this use are interpolations made later than that time." In spite of being used in a modern context to justify egalitarianism under the notion of both yin and yang being "necessary", in practise the concept of yin and yang has led to justification for China's patriarchal history. Particularly under Confucianism, yang (as the sun principle) is considered superior to "yin" (the