The five elements refer to the movement and changes of the five basic material elements, i.e. , wood, fire, earth, metal, and water. The theory of the five elements originated when the ancients took the functional properties of the five materials which are the most familiar to people in their daily life, as representative concepts to classify things' properties. The ancients also took the relationships of inter-generation and inter-restriction among these five elements to discuss and infer the mutual relationships and the cornplicated laws of movement and changes among things. Thus, the theory of the five elements also pertains to the materialism in ancient Chinese philosophy. Starting from the perspective of materialist dialectics in very early times, the five elements were regarded as the widespread law of the universe. For instance, it is said in Chapter 64 of the Spirit Pivot, "Between heaven and earth, and within the six directions,all things cannot be away from the five. So the human being corresponds to it, too. "Chapter 66 in Plain Questions also states, "The five movements and yin-yang are all the laws of heaven and earth. " Here the "five" and "five movements" each refer to the five elements. Professor Ren Yingqiu pointed out in his Six Lectures on the Basic Theories of TCM, "The theory of the five elements in TCM is a kind of comparatively intact primordial theory of common systematics with the oriental color. " The perspective of common systematics mainly includes the following aspects: (a) an emphasis on studying things with a consideration of the whole, and the belief that the whole is composed by its component parts in a certain connective form; (b) a belief that things must realize their component part as well as observe their connective form and structural relationships£» (c) a belief that the existence of the whole system cannot be apart from its particular surroundings£»and (d) a belief that there exists a similarity or logical commonality between various systems of different types or different grades. It should be pointed out that the theory of the five elements in TCM embodies the perspective and thought processes of the above-mentioned systematics, and takes this viewpoint to generalize and analyze things' structural composition and their internal relationships." According to the viewpoint of the five elements, the ancients held that the universe and the natural world all are composed by materials with the five properties, and the development and change of various things and phenomena are the result of the movement and interaction of materials that possess these five properties. In TCM, "the theory of the five elements" is chiefly applied to generalize the functional properties of viscera and structure, to demonstrate the internal laws of the mutual relationships among the five zang-viscera systems, and to sum up some mutual relationships between the body and the natural world. In sum, it is used to expound upon the human body's entire structural relations in order to guide the clinical analysis and treatment.
