An analysis on "(The reaction between) one Yin and one Yang is called Dao

proposition of The reaction between one Yin and one Yang is called a-rouses three issues: the relationship between one Yin and one Yang, the relationship between the Dao and one Yin one Yang, and whether Dao is monistic or dualistic after all. With the help of the history of Chinese and western philosophy, this paper analyzes these issues and concludes that the proposition of The reaction between one Yin and one Yang is called has completely covered the three implications of simplicity, changing, and unchanging of Yi.