Originating in ancient Chinese philosophy, yin and yang (traditional Chinese: 陰陽; simplified Chinese: 阴阳; pinyin: yīn yáng, , ) or yin-yang is the concept that there exist cosmic principles or forces that are opposite but complementary, which interact, interconnect, support and perpetuate each other. Together they form a dynamic system in which the whole is greater than the interdependent components, and both parts are essential for the cohesion of the whole.
In Chinese creation theory, the universe develops out of a primary chaos of primordial qi or material energy, organized into the cycles of yin and yang, force and motion leading to form and matter. "Yin" is retractive, passive, contractive and receptive in nature in a contrasting relationship to "yang" that is repelling, active, expansive and repulsive in principle; this dichotomy in some form, is seen in all things in nature and their patterns of change, difference and transformations. For example, biological, psychological and cosmological seasonal cycles, the historical evolution of landscapes over days, weeks, years to eons. The original meaning of yin was depicted as the northerly shaded side of a hill and yang being the bright southerly aspect. When pertaining to human gender, yin is associated to more rounded feminine characteristics and yang as sharp and masculine traits.