The answer is: according to Daoism, Yin and yang represents the ideal of ideal as opposing forces energetically, such as dark and bright, good and evil, are connected with each other.
Examples: winter and summer, men and women, order and disorder. The idea being conveyed is that one force depends on the other in order for them to exist.
The symbolism of the yin and yang is that they are the cicles in which the material energy from the creation of the universe is organized. While yin is the receptive (representing moon, night, feminine and so forth) and yang is the active(representing sun, day, masculine and so forth), both of them together represent continuous change and expose the duality in our universe.
