The yin yang model of thinking is most essential to the Chinese cosmology, ontology and outlook on life. This paper is a systematic discussion of such a dialectical way of thinking and its significance. It starts with investigating the origin and the meaning of terms “yin” and “yang”, and explains the later developed yin yang doctrine; it then shows how greatly and profoundly the yin yang model of thinking has influenced Chinese philosophy and Chinese character. It concludes that Chinese naturalistic, (...) dialectical, and optimistic attitudes toward the world and life are all based on the yin yang model of thinking and that the yin yang doctrine is the starting point for anyone to understand Chinese people and their philosophies. (shrink)