The core of feng shui teaching is about designing our ideal living environment. The guiding principle behind this is the natural principle. The fundamentals of the natural principle stems from the Yin-Yang theory.

What we should try to fine tune in our lives, is the striving for the balance of yin and yang, the two polar aspects of every existence and transformation.  This same principle should also guide our activities in response to the natural seasons.  Seasons has its Yin-Yang cycle.  In spring, yang arises and by summer, yang reaches to the maximum.  Come fall, yin appears and during winter, yin reaches the maximum.  Yang is dynamic and active while yin is the opposite. If we are to live in synchronization with the seasons, we should be active in spring and summer then slow down in fall and rest in winter.  In the natural world both plants and animals exhibit this pattern.  In old times, farmers also followed this pattern; after fall harvesting, the farmer takes a good rest until the spring sowing time.  However, after the industrial revolution, and in this modern society, we have no longer followed the natural way. The human has become a machine. The mechanical 9-5 daily working hour and 5 days a week working schedule throughout the year, in the name of proficiency or whatever reasons, prevent us to resonate with the natural rhythm. It is not ideal for health, emotion, and spiritual growth. It is a stupid human invention. We have lost sight of the big picture- a picture of wholesome living.

Shan-tung Hsu Feng Shui, Yin-yang