The Three (Trinity) — heaven, Earth, humanity — is the outcome of the movement from Tao/Taiji.

To Laozi it was Tao, One (Qi), Two (Yin + Yang), Three.

To Zhou Dunyi it was Taiji/Tao, Two (Yin Qi, Yang Qi), five elements, myriad creatures.

The correspondences summarize all kinds of relationships — from a human body to the environment, from sensation to philosophy. Nature, society, and humanity form a trinity.

In the minds of early Chinese, things on Earth depended and relied on each other. The logical attitude was that humans are not conquerors of nature — we cannot loot from the Earth too much. Our survival depends on heaven and Earth together.

Doctrines about the suitable manner of living were developed and passed down to succeeding generations in time-tested knowledge.

To adapt was the best way to achieve a balance against contradictory forces, Yin and Yang, which crystallize all observations and experiences of the world.

Yin and Yang serve as an analog for basic, contradictory natural forces.