Walter Benjamin writes about Threshold Experiences.

The German word is Schwelle. Like so many words in German, this one holds potent tension.

It is a space/time flux of transition without a hard walls or boundaries. Not anything as solid as a door, for example. I think of it as a kinetic zone that vibrates and shifts as part of us and our passage.

This idea and others from Benjamin (especially his Konstellation) are inspirations for the navigational approach to mind, whereby we can envision each binaryrelation as part a constellation, thus understanding it as a threshold rather than something to be resolved.

In not resolving it, we somehow shift to notice more points beyond what we had taken as closed.

(I first bought this book at St Marks Bookshop, if anybody happens to remember that place in the EV)