The dark female of chapter six is not an isolated image. The Tao Te Ching reaches consistently for the female, the maternal, the low, the yielding, the watery and the infant, and against the male, the high, the hard and the assertive, and the pattern is systematic enough to count as a position.
The mother appears in chapter one as the named source of the ten thousand things, in chapter twenty as what the speaker values while everyone else is at the feast, in chapter twenty-five as what the nameless thing might be called, and in chapter fifty-two as what to hold to after knowing the children. Chapter twenty-eight instructs a reader to know the male but keep to the female. Chapter sixty-one describes a great state as the female of the world and says the female overcomes the male by stillness. Chapter seventy-six argues from the fact that the living are soft and the dead are rigid.
Two cautions are worth stating. The book is not describing women; it is using a gendered pair of terms as an analytical vocabulary, in a culture where that pair was already a standard way of sorting qualities. And the preference is not sentimental. The claim throughout is strategic rather than tender: the yielding term wins. Water wears down stone, the supple tree survives the storm, the state that lowers itself takes the other one.
That is why the imagery cannot simply be extracted as a philosophy of gentleness. It is an argument about what actually prevails.