The short of it:
Known things come from the unknown thing.
6. The Production of Material Forms.
The spirit (like the perennial spring) of the valley never dies. This (Spirit) I call the Abyss-Mother. The passage of the Abyss-Mother I call the root of heaven and earth. Ceaselessly it seems to endure, and it is employed without effort.
6. ‘the completion of material forms.’
The valley spirit dies not, aye the same; The female mystery thus do we name. Its gate, from which at first they issued forth, Is called the root from which grew heaven and earth. Long and unbroken does its power remain, Used gently, and without the touch of pain.
6. The Completion of Form.
“The valley spirit not expires, Mysterious woman ’tis called by the sires. The mysterious woman’s door, to boot, Is called of heaven and earth the root. Forever and aye it seems to endure And its use is without effort sure.”
The long of it:
What better metaphor for the mysterious origins of the Universe, than the source of human reproduction? Chapter 6 of the Tao Te Ching introduces the potent darkness of the “Abyss-mother” as Universal genesis.
The Universe waits, patiently potent. This is non-action, the unknown, the Great Mystery. From its unknown gate comes EVERYTHING (heaven and earth). This is action; the knowable, tangible world.
Those skilled at way-making (Tao), know the Universe pulsates with this rhythm of non-action/action that cannot be contained. So they wait. They know something will happen, must happen; but do not rush things.
To act without non-acting would be like running into traffic without looking.
Instead, wise people marry action to non-action (the Valley Spirit). This is the effortless action our translators are referring to.
Long and unbroken does its power remain, Used gently, and without the touch of pain. -Legge
Nicely put.
-TB