The term 'Dark Principle' is a philosophical concept that refers to the idea of an underlying force of evil in the universe. It is often associated with the Chinese philosophy of Yin and Yang, which states that two opposing forces, Yin and Yang, exist in the universe and are constantly in a state of balance. The term 'Yin' is used to refer to the dark, negative force in the universe, and is represented by the symbol of a black dot within a white circle.