Tao Te Ching

“the concepts of the creative and the receptive that originate in the I Ching are symbolized by Heaven and Earth. Through the union of heaven and Earth, there develop the 'ten thousand things', that is, the outer world.”

— Lü Dongbin 呂洞賓 1 via Richard Wilhelm
(Lü Tung-Pin)

from Secret of the Golden Flower 太乙金華宗旨; Tàiyǐ Jīnhuá Zōngzhǐ