Yin And Yang Symbol

According to ancient Chinese philosophy, the two fundamental principles, one negative, dark, passive, cold, wet, and feminine (yin) and the other (yang) positive, bright, active, dry, hot and masculine.
The interactions and balance of these forces in people and nature influence their behavior and fate.
The balance of yin and yang in the individual, nature, and the cosmos is symbolized by a circle separated by an "S" shape, one half of the circle dark and the other light.
Used in the Western world to express any dualistic, reciprocal control system in which one influence tends to promote things that the opposing influence tends to inhibit.