Yin and Yang 阴阳

Yin and Yang 阴阳

Tao begets One, One begets Two,

The Two is Yin and Yang, a concept of duality that is seemingly contradictory to each other but it is not. Yin and Yang complement each other. 

There is a saying of 孤陰不生，獨陽不長, the lonely Yin does not engender, the lonely Yang does not grow. The saying emphasize the importance of harmony of the duality. In the Taiji diagram, a black dot inside the white area and a white dot inside the black area indicates there's a seed of Yin inside Yang and there's a seed on Yang inside Yin, Yin cannot exist as absolute Yin neither could Yang. When Yin reaches climax, it recedes in favor of Yang, and when Yang reaches climax, it recedes in favor of Yin. The concept in Chinese is known as 阳至阴生，阴至阳生。 

Everything can be categorized into Yin and Yang in extreme detail according to necessity. 

As it is said 陰陽者，數之可十，推之可百；數之可千，推之可萬；萬之大，不可勝數，然其要一也。 

Yin and Yang, to count could be of tens, to calculate could be of hundreds, to count could be of thousands, to calculate could be of ten thousands, the greatness of ten thousands is uncountable, but has to be one.

Generally many things can be classified according to Yin and Yang, listed below are some examples useful for Bazi chart analysis.

Yin                         Yang

Passive                   Active

Slow                       Fast

Gradual                  Abrupt

Earth                      Heaven

Internal                   External

Odd                        Even

Metal                      Wood

Water                     Fire

Still                         Moves

EB                          HS

Follows                   Persists

Against                   Conform

Gentle                         Tough

And the list goes on.

There is also a misconception that Yin is evil and Yang is good, which is not true, according to Taoism, good is unknown, and for mankind good deed is perceptual, it could be Yin and could be Yang. 

Furthermore, good deeds can be categorized into 阴德 (Yin virtue) and 阳善 (Yang goodness). Yin virtue is hidden virtue, good deed done that is not known to others, its karmic rewards comes back gradually, unseen by doers. Yang goodness is good deed done known to others, its rewards  would be obvious to the doers, for example a charity work as a form of publicity to an individual or an organization is a form of Yang goodness.