The relationship between them is typically described in terms of a mountain and valley illuminated by the sunlight.
Yang which literally means the ‘sunny place’ or ‘south slope’ is the mountain, the protruding more outward energy form and also the brightly lit portion of the symbol.
In their dynamic aspect, Yin and Yang symbolize that they truly compliment and completely merge in each other- to create all of creation. Here, Yin represents the primal female energy and Yang, the primal male energy. The interplay of this male and female primal energy creates everything in this manifested, material world of form and spirit.
Sun, which represents the source of light (the Divine Spirit or the essence of Tao) illuminates this creation and the constant play of Yin and Yang.