Tao Te Ching

“The most truthful and capable of giving full realization to their human nature can form a trinity, a union of heaven, earth, and man.”

— Zisi 子思 481 – 402 BCE via Daniel K. Gardner, Shan Dao
(Kong Ji or Tzu-Ssu)
Confucius' grandson and early influence on Neo-Confucianism
from Doctrine of the Mean, Maintaining Perfect Balance, Zhongyong 中庸