blesstheworld.com glossary

Yin and Yang ~ Usually thought of as opposites, yin and yang are merely opposite poles of the same discreet whole and describe an exchange of energy (chi) within that whole.

Consider wind blowing from one end of a hallway to the other. The hall itself is the discreet whole; the end of the hall where the wind begins is yang, dynamic, masculine; the end of the hall where the wind arrives is yin, receptive, feminine. Yin and yang merely describe the flow of energy in the hall; they are not features of the hall itself. The door or window where the wind enters the hall is yang in relation to the hall but yin in relation to the outside ~ it receives the wind into the hall (yin) but is also the dynamic force that originates the wind in the hall (yang). It is a matter of perspective. The flow of energy can also change under other conditions. Understanding the principles of yin and yang are the basis of martial arts and all Eastern philosophy.

Do not make the mistake of thinking that yang energy is more powerful than yin. The I Ching, the Book of Changes which proposes the foundation of yin and yang, feng shui, and all relationships states clearly that the yin triumphs over the yang by merely allowing the yang to exhaust and defeat itself. (Do not confuse this with yin feng shui which pertains to graveyards. The principles of yin feng shui are not pertinent to houses of the living.) Yin-energy treatments have less potential for creating karma than yang-energy treatments. However, in many instances, only yang treatments will be effective. See Feng Shui Every Day.