One is nothingness, the other is existence. Two in life, two in one. The three that arise from the union of the two in one's life is virtue, which is nature. One is yang and the other is yin. Yang teaches Yin, and Yin receives Yang. The rotation resulting from the interaction of yang and yin is virtue and nature. Yin and Yang are limited and out of balance. Yang imparts Yin and receives imbalance, resulting in positive and negative. Producing positive and negative rotations is still virtue and nature. (Lao Tzu) Li Shu said that Taoism is fine, but why is he Yin? This is really a sad story...