The Taoist philosophy of change ascribes any alteration in nature to the interplay of Yin and Yang. These are two complimentary opposites, which cannot exist without the other. They have various attributes, which characterize them. Yin is described variously as negative, soft, yielding, abyssal, dark, cold, receptive, resting, empty; whereas Yang is positive, hard, pushing, lofty, bright, hot, creative, working and full. They are used merely as descriptions of state, not as judgments of a condition. Gong Yi Taijiquan (tai chi chuan) is the physical manifestation of the philosophy of change as applied to body movements, therefore some parts of the body are described as Yin in some forms or postures, and Yang in other postures. The process of change is symbolized in the diagram below. In this figure Yin is portrayed as the dark area, and Yang as the light area. Each area contains within it the element of change; i.e. there is always some ‘Yang in the Yin and some Yin in the Yang’.