Every question concerns you looking or not-looking, doing or not-doing, knowing or not-knowing;
Never the thing (object) looked-at, done, known; never its being or not-being.
As long as there is you doing, it makes no difference whether there is doing or not-doing - for both are doing by you.
Paravritti, metanoesis, the '180 degree turn-over', is not a turning over by a 'doing or not-doing' you, a turning from positive to negative; it is not done by 'a you'. It is not done by any other 'entity' either. It is not done at all. It is the timeless, unceasing prajnaic functioning of our dhyanic non-being that becomes phenomenally present when there is neither doing nor non-doing, i.e. when there is 'fasting of the mind'.
It is not the object that is or is-not, but the cogniser of the thing that either is or is-not - that neither is nor is-not as a cogniser.
All looking, doing, cognising is the same process as looking for 'I' (the looker, doer, cogniser) as an object. Why? Because a you (I) is looking, etc., and also because every object ultimately is I. The looking for 'I' as an object is the looking that is all looking for all objects; so is the not-looking for 'I' as an object the not-looking for any object whatever.
But it is the looker, rather than the object, that neither is nor is-not. Always, always, in every case and context.* Therefore it is only when you (I) cease looking that the total absence of the looking you (I) can be present - and that is the '180 degree turn'.
Who is looking? As long as a 'who' looks, objects can be seen only as objects, and a looking 'who' cannot be replaced by WHO? which neither is nor is-not, as long as he is looking.
Only in the absence of both looking and not-looking can a looking, which neither is nor is-not looking, be present. And such presence is you ('I').
Is not that the message of the Diamond and Heart Sutras?
IINot clear enough? Let's look at it like this:
No object as such is either good or not good, which are attributes in the cognising of which by split mind there arises the supposition of a cogniser and of some thing cognised.
But there has never been a cogniser, and there has never been any thing cognised, object or attribute of object, which are split aspects of the prajnaic functioning which we are calling cognising.
Once one has been pushed, pulled or wheedled out of the notion that objects as such, and their attributes, are as we sensorially perceive and intellectually interpret them, and has apperceived that their objective existence, as well as ours, is entirely visionary, surely one can understand that all they are is their source?
What is a little more difficult to apprehend is that their source as such, subjectively, is all that even objectively they are.
Then, all that remains is to apperceive that what we are looking for is this which is looking.* The object also, of course, which phenomenally either is or is-not, noumenally neither is nor is-not, but only because it is integral in its subject.