The Yin-Yan
The yin-yan sign belongs to a group of symbols as it is a symbolic expression that the world is a blend of two polarities. The yin-yan is a core of Chinese philosophy, the symbol that implements the main foundations of that philosophy. This sign is a sign of harmony and interaction of polarities we have in this world. It states that there is no good or bad only, there are only blends of those and those blends together forms our life and all we have in this life.
The etymology of this symbol is rather interesting one as it has colourful history and underwent a number of changes of its meaning. The yin and yan at first were the names for two sides of a mountain. The yin is a name of the dark side of a mountain and the yan is a name for bright side of a mountain. The yan was a side that faced the sunrise and the tin was a side that faced the sunset. That is why during the day one side remained lighted and another remained dark till the moment the Sun comes to its zenith.
That was the initial meanings of the yin and yan. Soon the development of Chinese philosophy began and the world was explained as the mountain one side of which is dark and the other one is lighted. The symbol of yin-yan is represented as a circle divided in two parts and one part is black and the other part is white. Each of those sides also has the tiny spot of the colour of opposite side. Some scientists say that those spots are symbols of something good and something bad in evil and good appropriately. Though, there are those who state that those spots are simply the sun and the moon that lights the dark and bright side of a mountain.
One way or another it is known for sure that the yin-yan is an implementation of the whole concept of Chinese philosophy and vision of the world. That is a symbol of harmony and balance. According to that philosophy nor the harmony nor the balance of things and energy may be found in one aspect. The harmony is reached only by means of blending the polarities of one or another thing or event.
The yin-yan nowadays become the symbol of fen-shei the science or culture about ordering the things of one's home or office. The yin-yan of fen-shei has the same meaning with the yin-yan of Chinese philosophy. Actually, it was borrowed from the Chinese philosophy. According to fen-shei everything in house should be ordered in the way that will bring to balance the energy the house provided with, and the yin-yan is a symbol of the energy that brought to balance.
As you can see the yin-yan is an ancient symbol of harmony and appeared as a result of Chinese's vision of the world and cognising of this world. Though the yin-yan now is not only a symbol of Chinese philosophy it hasn't lost its authentic meaning and remains the symbol of a harmony. Though the fen-shei recognise it as a symbol of the balance of energy those are the same things. So, the yin-yan is one of the ancient symbols that keep their initial meaning even nowadays.