After my last post someone mentioned threshold theory to me.  This has its roots in anthropological studies of rites of passage, but in educational theory a "threshold concept" is one that, once understood, changes the learner's view of the subject: 

... there are certain concepts or learning experiences, which resemble passing through a portal, from which a new perspective opens up, allowing things formerly not perceived to come into view. This permits a new and previously inaccessible way of thinking about something.
— Ray Land, JHF Meyer, Caroline Baillie, preface to "Threshold concepts and transformational learning" (2010)

These are the difficult bits - the things that are hard to grasp and challenge the learner's existing ideas or understanding.  But they are also the parts that make the difference between a working understanding of a subject or true mastery.  

Difficulty in understanding threshold concepts may leave the learner in a state of “liminality”, a suspended state of partial understanding, or “stuck place”, in which understanding approximates to a kind of “mimicry” or lack of authenticity.
— Meyer, Land & Baillie - as before

This totally makes sense to me in terms of where I find myself.  I have these individual pieces of inspiration, skills and knowledge and a sense of reaching for an understanding that will bring them all together .... that is tantalisingly just out of my reach.  And to reach it, I may have to let go of some of my existing approach ... which is discomforting.   In the meantime, there's that sense of dissatisfaction - that nothing is quite in its place.  

A threshold has always demarcated that which belongs within, the place of familiarity and relative security, from what lies beyond that, the unfamiliar, the unknown, the potentially dangerous. ... all journeys begin with leaving that familiar space and crossing over into the riskier space beyond the threshold.
— Meyer, Land & Baillie, as before

But while it was fascinating to me to come across this thinking and to see how it relates to what I'm doing, the real lightbulb moment related to a different aspect.  I realised just how strongly I'm attracted to things that encapsulate that liminal edge - the space "in between" where one thing becomes another.  

Tide turning.  Snettisham (June 2014)

In the landscape, it's where the tide alternately reveals and conceals the land; 

all the edges disappearing ... Holkham Bay at sunset with the tide turning (July 2014)

... where the sky merges into the sea so that you can hardly see the horizon;

Blakeney Channel (March 2014)

... where dry land merges into mud and then water on the marshes.  

It's also those other transitions - where one season begins to turn into the next, changing light at dawn or dusk, marks of ageing or decay ... I could go on but you get the idea.  I like the fact that the edges between these things are not clear or distinct.  There is an ambiguity, in which you know that something is changing but it is a pattern of one thing flowing into another - not a clear stop / start.  

And these are just the visible manifestations.  I can also see links to ideas that are important to me about the boundary between knowing / not knowing; processes of change and transition; and the nature of our relationship with the wider natural world.  

Salts Hole at Holkham.  (September 2014) 

Salts Hole (above) used to be connected to the sea via a network of saltmarsh creeks.  It is now cut off by a ridge of sand dunes and pine woods that has taken many years to form.  The water is salty enough to support saltwater creatures such as sea-anemones, even though it is now almost a mile from the sea.  The brackish water both reflects the sky and conceals what lies within the pool.  It is both transparent and opaque.  It is the essence of a liminal space.  In many cultures, pools have been seen as gateways (thresholds) to another place - the underworld, underwater lands - and as a symbol of the unconscious.  So many layers of liminality.

I want to develop this.  It's already there in my work, but I think I can do more with it.  Which suggests a way forward.  

More about threshold concepts (pdf)

More about the anthropological origins of ideas about liminality