Tao (the Way, or one’s doctrine).

The concept of Tao is based upon the understanding that the only constant in the universe is change, (ie. I Ching, the “Book of Changes”) and that we must understand and be in harmony with this change. The change is a constant flow from non-being into being, potential into actual, yin into yang, female into male. The symbol of the Tao, called the Taijitu, is the yin yang confluently flowing into itself in a circle. More in Wikipedia or at the Amazon bookstore: Tao Books