Yin and Yang
The terms Yin (阴) and Yang (阳) create one of the foundations of TCM. When Yin and Yang work together there is a sense of balance in the human organism.
The symbol of Yin and Yang represents balance (harmony) between the active and the passive. They are considered complementary concepts and powers rather than contradictory ones.
In Chinese medicine all opposites relate to Yin and Yang. Yin stands for the terms darkness, cold, calm and passive; Yang is the opposite and stands for brightness, warmth, movement and active. Within the body the organ (Yin) only loses his influence without his metabolism (Yang). Deprived of the organic substrate (Yin) no metabolism (Yang) can take place. Yin contains a Yang quality and vice versa. The two aspects form a whole. This dynamic marks both the complementing and transformative nature of Yin and Yang. In Harmony one does not outweigh the other in any way, there is a balanced flow of constant transformation.