Not-Two’: Àdvaitham, a term that predates Shūnyam. Yājñavalkya defined it as simply: ‘Neither before nor after; Neither inside, nor outside’.
Its earliest scriptural definition was as: ‘One without a second’ [Ekam Sat].
I once sat in on a Sangha meeting where the learned monk was whipping up a lather: ‘Not-Two; Not-Three; Not-Four’, he pounded.
This is not what ‘Not-Two’ means. It is not a swipe at all notions of plurality. Once you miss the significance of ‘Two’, you can go all the way to quadrillion. And it wouldn’t make any difference.
‘Not-Two’ is a statement of Truth, not an appellation, not a name for an ‘Object’ [concept, process, state, sentiment, anything you can objectify]. And the confounding of ‘Not-Two’ as a conventional reference, a name, is pervasive in the historical literature.
‘Not-Two’ actively locks in the Subject in a verbal hog-tie. You may not not say a word [or write a Post] about it. Except to call it ‘Not-Two’.
‘Not-Two’ has lots of layers to it and you won’t really notice them until you slip on one. But the most relevant can be readily listed.
First, the open-ended: ‘Not’.
Next, the Principle of Co-Dependence in its two directional applications.
And finally, our ready tendency to abstract into referential structures [‘Doubles that Refer’] and hence make our World amenable to Logic and Language.
In particular, expressions formulated as ‘Sign’, and further extended in Logic, Language and ‘Thought’. And then cheerfully contracted or expanded until we get seriously lost.
‘Not-Two’: You can carry it around in your shirt-pocket. Bounce it, baby it, bully it. It will spring back to shape.