The known source of all the forces in heaven and earth is the Yin Yang Qi.
So...
Seek the principles of the Celestial Soul, Earth Soul, and Human Soul.
...
Before the Desolate Cliff, Li Yuan sensed the expansion of his Golden Body Immortal Appearance behind him, and suddenly, he rested his chin in contemplation.
Various past images and memories emerged in his mind.
Suddenly, he had a moment of enlightenment.
Perhaps:
The Celestial Soul is [Yang[Yin]Yang];
Since the Human Soul seems to be [[Yin][Yang]];
Thus continuing the inference, the Earth Soul might be [Yin[Yang]Yin].
The connection between the three souls and humans is... one's own Divine Soul.
Yet, regarding the Celestial Soul, the human's Divine Soul is hidden in "Yin";
Regarding the Earth Soul, the human's Divine Soul should be hidden in "Yang." No! The Divine Soul cannot be hidden in "Yang," so it still maintains the original body;
