The Three Realms stratify existence into Heaven, Earth, and Human consciousness.
The Three Powers — Heaven, Earth, and the Human between them — structure existence as a triad rather than a pair. Heaven sets pattern and time; Earth provides substance and place; the Human stands in the middle, the one who reads the first and works the second.
San Cai unlocks the idea of the mediating term: not opposition resolved but opposition bridged. It positions the person not as a spectator of the cosmos but as an active joint within it, responsible for aligning what is above with what is below. Agency becomes structural.