廣弘明集 9.49

9.49

洞神三皇經。稱西域仙人曰皇文者。乃是三皇已前鳥。跡之始文章也。又云。三皇者。則三洞之尊神。大有之祖氣。天皇主氣。地皇主神。人皇主生。三合成德萬物化生。

The Dongshen sanhuang jing, referring to the immortals of the Western Regions, says: "Huangwen (Sovereign Script) was the writing at the very beginning of bird tracks prior to the Three Sovereigns." It also says: "The Three Sovereigns are the revered spirits of the Three Caverns, the ancestral qi of the Great Existence. The Heavenly Sovereign presides over qi; the Earthly Sovereign presides over spirit; the Human Sovereign presides over birth. The three unite to complete virtue, and the myriad things are transformed and generated."