In Chinese philosophy Yin and Yang are the fundamental principle of all things. The key of a good Feng Shui is the balance between Yin and Yang and that creates harmony between the 5 elements. Yang is sun, Yin is moon, Yang is summer, Yin is winter. Time is Yang and space is Yin. Father is light and Yang, while the mother is shade and Yin. This demonstrates that Yin and Yang are in a dualistic relationship. The same system can be applied to the domestic environment: for example, the bedroom where we rest is Yin, the livingroom where guests discuss vividly is Yang.