The ancient Chinese came to know early that the nature or state of things change to their opposite under certain circumstances. In the Northern Song Dynasty, Cheng Yi (1033-1107) gave a detailed description of the rules of such change when he argued that “when reaching an extreme, things are bound to revert to their opposites.” This view believes that things tend to change when reaching an extreme in their nature or state. In such a state, things inevitably transform themselves into their opposite.

When reaching an extreme, things are bound to revert to their opposite state. This is the way things work. When there is life there is death, and when there is a beginning there is an end. (Writings of the Cheng Brothers)