Yin and yang
The concept of yin and yang began as an element of Chinese philosophy, and has since become an important part of East Asian mysticism. The concept still plays a significant role in traditional Chinese medicine.
 Basics of the Philosophy
The essence of yin and yang is that the universe is made up of complementary dualities. As opposed to Western dualisms, in which the mind and body or good and evil are resolutely opposed and unable to be bridged, traditional Chinese philosophy holds that all things contain elements of both yin and yang, and therefore both are necessary for the implied balance of the universe.
Yang is represented as the masculine, active, light, warm, etc. Yin, by contrast, is feminine, passive, dark, cold, etc. The sun is yang, the moon is yin. It should be noted that neither is good or bad, but have different effects on different things. A person should strive for a balance of each.
 Yin and yang today
Although there is only one oblique reference to them within the Tao Te Ching, yin and yang play a major role in Taoism, but the overall idea was considered vital to becoming in tune with the Tao. Moreover, in many places the book refers to standing with the "feminine" or the "dark," a reference to the "yin." (Religious Taoism (daojiao) put far more emphasis on the maintenance of "yin" and "yang".)
“”All in the world know the beauty of the beautiful, and in doing this they have (the idea of) what ugliness is; they all know the skill of the skilful, and in doing this they have (the idea of) what the want of skill is.
“”So it is that existence and non-existence give birth the one to (the idea of) the other; that difficulty and ease produce the one (the idea of) the other; that length and shortness fashion out the one the figure of the other; that (the ideas of) height and lowness arise from the contrast of the one with the other; that the musical notes and tones become harmonious through the relation of one with another; and that being before and behind give the idea of one following another.
Yin and yang are considered extremely important to Chinese geomancy (feng shui, or "wind water"). Many people would, traditionally, build houses so as to increase the amount of yang energy given off by the sun. Examples of this included building south of mountains and north of rivers, where the sun's yang was supposed to collect. Feng shui also considers siting a building to make it more defensible against enemies. Moreover, expert layout of rooms would allow for yin and yang to be used most effectively. While the concept might have some validity regarding the location and layout of a house, feng shui also employs magic to protect against problems with the use of mirrors, feathers and other items placed in strategic locations. The efficacy of these items often involves some sort of word play or resemblance of word sounds to achieve their intended effect.
 Other kinds of woo
In modern Western societies, yin and yang is most often associated with various kinds of woo. In many of these cases, the philosophical background of the concepts of yin and yang is usually discarded entirely for warm fuzzy pronouncements about being in touch with "both sides" of oneself or the universe, or not getting caught up in antagonistic dualities. This sometimes involves the use of some kind of Eastern-seeming rituals or procedures, completely divorced from the cultural milieu that gave birth to it.
Also, many of the tenets of modern Neopaganism at least sound like they are related to yin and yang, particularly the focus on "balancing" male and female energies.
- ↑ http://www.qi-journal.com/tcm.asp
- ↑ "The Tao gives birth to One. One gives birth to Two. Two gives birth to Three. Three gives birth to all things. All things have their backs to the female and stand facing the male. When male and female combine, all things achieve harmony. (Chapter 42) "
- ↑ http://www.edepot.com/tao8.html