yin and yang
in Chinese philosophy, the two opposite but complementary aspects of the fundamental principle governing the universe. Originally, the words referred to the shady and the sunny side of a hill. The concept is represented by the Chinese symbol (the Taijitu) that also represents Taoism. Yin and yang are the two forces or principles that can be seen at work in all phenomena. Sometimes one is dominant, sometimes the other, and all things ultimately revert to their opposites. In simple terms, yin is characterized as negative, passive, and feminine, among other things, whereas yang is seen as positive, active, and masculine, among other things. Understanding the principles of opposition, interaction, and especially harmony inherent in yin and yang is, however, as important as understanding the particular characteristics associated with each of them.