Dao De Jing chapter 6: 'The valley spirit does not die; it is called the mysterious feminine. The gate of the mysterious feminine is called the root of heaven and earth. Dimly continuous, it seems barely to exist; use it, and it is never exhausted.' The Mawangdui manuscripts carry the passage essentially intact, and Wang Bi's commentary (3rd century CE) reads the valley as emptiness itself, not a deity.
Later religious Daoism and many modern readers identify the valley spirit with a goddess or womb cosmology, folding the passage into deity cults and fertility imagery. The received philosophical tradition, from Wang Bi onward, resists personifying it.
The valley is the counter-image to every monument: it endures precisely because it is low, empty, and receptive, the female and the downward as cosmic position. Chapters 28 and 61 extend the logic, the state that takes the lower position gathers the world.
If the root of heaven and earth is described as a valley, what does height actually buy you?