tao teh ching 6

The valley spirit never dies;
It is the woman, primal mother.
Her gateway is the root of heaven and earth.
It is like a veil bareley seen.
Use it; it will never fail.

Interestingly, Cheng Man-ch'ing sees this as a text on the controlling
and subtilising of breath. A rather interesting text on one aspect of
this - the so-called 'microcosmic orbit' - is to be found at
http://www.daoistalchemy.com/alchemy.php# (click on the links
concerning the orbit and the meridians. Can't guarantee the rest -
haven't actually looked yet).

Wang Pi says: The Valley Spirit is the nothingness in the centre of
the valley. It has neither form nor appearance and is utterly free of
contrariness or disobedience.. Lying low and unmoving, it maintains
its quiescence and never weakens. Even though all things are completed
by it, we do not see its form, for this is the most perfect thing.
Lying low and maintaining quiescence, it cannot be grasped in order to
give it (the Tao) a name, so the text refers to it as the Mysterious
Female... The gate is the place from which the Mysterious Female
comes. Because it is rooted in that from which it comes, it is the
embodiment of the great ultimat [yü chi t'ung t'i], which is why the
text refers to it as 'the root of Heaven and Earth'. Do you wish to
say that it exists? Its form has never been seen. Do you wish to
contend that it does not exist? The myriad things are produced by it.
Thus the text says, 'On and on, with only apparent existence'. Not a
single fails to come to completion and yet it never tires. Thus the
text says 'its functions are inexhaustible'.

What is interesting about breath is that, the finer the breath, the
finer the thought-patterns. This is possibly easier to spot the other
way round: the rougher the thought-pattern, the rougher and more tense
the breath (look at anger, fear, intense desire where the breath is
often blocked in the upper chest)... The Taoist saying has it that the
wise person breathes to their heels and gets a belly-ful; the ordinary
person breathes into the throat and chokes to death. Interesting
ideas!
When the thoughts are very subtle, we can begin to intuit the fountain
of youth that is the ever-changing display, begin to perceive that the
cloudlike forms are, indeed, just like 'mist', and that they swiftly
transform and pass away, only to be replaced by others in
never-ceasing succession.
And we can begin, also, to see through them, see their transparency
and thus take control of our own nose-ring, no longer needing to be
pulled right and left by these "brilliant ideas".