I just recently ran across the philosophy behind Yang and Yin, and thought it would be interesting to share it, so the visitors to my site can read about it.

Yang Yin
   
Yang is the strong, male, creative, giving force, which is associated with heaven. The heaven above us is always in motion and brings about change. Yang is associated with the following ideas and things: Yin is the quiet, female, intuitive, receiving force, which is associated with earth. The earth is the source of life, it provides us with what we need to survive. Yin is associated with the following ideas and things:
   
- Day, Light
- Sunshine, Fire, Heat
- Summer, Spring
- Even Numbers
- The Sun
- South, East
- Left, Up
- Intellect
- Active, Dynamic
- Expansion, Increasing
- Innovative, Reformative
- Mountain
- Desert
- Straight Line
- Hard
- Dissolving
- Physical (Observable) World
- Tiger
- Bladder, Intestines, Skin 		- Night, Dark
- Rain, Water, Cold
- Winter, Autumn
- Odd Numbers
- The Moon
- North, West
- Right, Down
- Intuition
- Passive, Static
- Contraction, Decreasing
- Conservative, Traditional
- Valley
- River
- Curve
- Soft
- Solidifying
- Psychological (Astral) World
- Dragon
- Kidneys, Heart, Liver, Lungs
   
In Chinese philosophy, the rhythm of life, which pulsates through the universe, is the action of complementary principles, Yin and Yang. The T'ai-chi T'u diagram (left) illustrates this principle. The symmetrical disposition of the dark Yin and the light Yang suggests cyclical changes. When Yin reached its climax, it recedes in favor of Yang, then after Yang reached its climax it recedes in favor of Yin. This is the eternal cycle. The dots inside the white and black halves indicate that within each is the seed of the other. Yin cannot exist without Yang and vice versa.

The ideal state of things in the physical universe, as well as in the world of humans is a state of harmony represented by the balance of Yin and Yang in body and mind.