Noumenon...

VOLITION, then, would seem to be an illusory inference, a mere
demonstration on the part of an energised I-concept, resulting either
in frustration or fulfilment and thereby being the source and
explanation of the notion of karma. Sentient beings are entirely
'lived' as such, as has often been noted by philosophers and endorsed
by metaphysicians, and the psycho-somatic phenomenon is inexorably
subject to causation. That is why sentient beings as such, as the
Buddha is credited with stating and re-stating in the Diamond Sutra,
are not as entities. That, also, is why, since as phenomena they are
not, noumenally—though they cannot be as entities or as anything
objective—nevertheless, they are as noumenon.

And noumenon, by definition being integrally devoid of any
trace-element of objectivity, is not, cannot be, in any sense
whatever—since all forms of being must necessarily be objective. Here
language fails us and must be left behind like the raft that has
carried us across the river. All we can say is something such as
'this, which is all that sentient beings are, itself is not'.
If this is not understood it will appear unsatisfying but, understood,
it will appear luminous and revelatory, and for the obvious reason
that the understanding is 'itself this noumenon which we are.
But here the eternal reminder is necessary: phenomena which, as the
term asserts, we appear to be, are nothing but noumenon, and noumenon,
which is all that we are, though as such itself is not, is as
phenomena (as its appearance).
'Volition', therefore, though it is not—is only an appearance
phenomenally—is noumenally and may be regarded as an objectivisation
of noumenality. As such we know it as buddhi or prajnd, as intuitional
inseeing and, knowing it, it is ourselves, all that we are, which—in
the knowing of it—we are knowing, for this which we are is this
knowing of it.
All very simple, evidently, until you try to objectify it in words.

from The Open Secret
Ch. 3 Volition
Wei Wu Wei