150 BCE

The Huai-nan-tzu, another definitive text of the Taoist library, is written. It compiles a wide array of Taoist writings, serving as something of an encyclopedia featuring writings from a host of different Taoist writers. The main focus is one the subject of the cosmos, time, human action and the underlying connection between the three elements; it featured such Taoist principles as ch’i, yin and yang (the balance between two extremes or opposites that naturally asserts itself in the forces of the natural world).