[Exploration and analysis of theories of five phases, eight trigrams and four elements].

The theory of five phases is significantly different from that of eight trigrams of I Ching (Book of Changes): the eight trigrams represent the materials or phenomena in the nature, whereas five phases put "metal" created by human activities into nature, which organically incorporate the human activities and all the things in the nature and promote the formation of holistic concept of heaven and human being. Without the attendance of man, earth can't generate metal, metal can't restrict wood, and metal can't generate water. So, it can be concluded that the five phases is the improved eight trigrams. Together with monism of original qi and the dualism of yin-yang, it contributes to Chinese medicine the scientific world view and methodology to shake off wizards, and is also the root cause for the Chinese medicine being good at resolving complicated problems. The theory of five phases is also significantly different from the theory of four elements in the western world: The five phases create the relationship of the interaction and interrelation among everything on earth and is the embryo and basis of systemic science. The theory of four elements belongs to constructivism and is the sprout of analytical science.