The two symbols of Yin and Yang are related to heaven (the astronomical aspect) and Yang, the earth (its geography).It is practiced only to bring life improvement. Through Feng Shui, man tries to use whatever he can through all natural forces to achieve harmony, prosperity and vitality. In other words, he tries to use Mother Nature's resources to exist in harmony on this earth. In ancient times, it is used widely in buildings of spiritual importance like tombs, and even in dwelling places.
Yin and Yang are symbolized by the moon and the sun respectively, the two main and active yet opposing forces of nature. It is said that Yin is merged into Yang and vice versa. Harmonious existence of such opposing forces is the life giving force on the globe like hot and cold, light and darkness. Yin's base meaning is 'shady side' which means the side of the mountain where the sun does not reach, the side not facing the sun. It is the 'female' component of the sign and is associated with the earth, its cold north. All even numerical come under Yin. Yang, on the other hand, is the 'male' component of the sign and means matters relating to heaven, the Emperor, South part of the earth and the dragon. All uneven numerical come under Yang.
The chaos in man's lifestyle brought about by modernization has disturbed the peaceful and co-operative living on earth. Therefore, through Feng Shui, man tries to bring back the same by adopting principals of balancing the energies of nature. The proper flow of these energies is also blocked by buildings with modern architecture which they believe brings about awful consequences on all those residing in such buildings.
Of course, man agrees that not everything is in his hands and there are certain external forces which have their effects on humans. These forces are the basic elements of the earth meaning fire, water, wood, earth/soil and metal, its electromagnetic fields, its gravity and directional influence. Man needs to live in harmony so that he can have all the good benefits of the energies of nature thus improving on his life. Therefore, Feng Shui claims to enable man in understanding the external forces in his environment to live in a manner which benefits his life, and not to live against it. It claims that with adopting the concept, man can see good opportunities and take advantage of them rather than miss them. He performs better and more intelligently.
The five elements of Feng Shui, as mentioned above can either help each other (grow/produce), counter each other (control/neutralize) or weaken each other (destroy/non-progression). For example, for wood energy (in wooden items, plants) addition of water can bring about a better item or nourishment to the plant. Water, as in a fountain, works collaboratively with mirrors, water images and colours like blue of any hue.