What is yin/yang?
Yin and yang do not have their own inherent reality. They are only description, types of movement, alternative indicators of the continual flow of change. Originally, yin referred to the nouthern, dark side of a mountain and yang to its southern or sunny side. Heads or tails, we might say; they always make up the two sides of the same reality. Yin and yang are the concerted movements of life and exist only within the dynamics that unite them.
Yin and yang are not static, separate, symmetrical entities. In fact, in order to speak accurately about yin and yang, the two terms must be presented together as one: yin/yang. The essence of yin/yang is neither yin oor yang but the dnace created by their union.