“They aren’t something you can walk up to and touch,” Jerrold E. Marsden, an engineering and mathematics professor at Caltech, said of the structures. “But they are not purely mathematical constructions, either.”
Marsden is talking about the boundaries between regions of flowing water or air, regions marked by different velocities. Don't think of them as rigid, though. They are constantly changing - the patterns themselves flow too.
I know that it is this very sort of phenomena that some anthroposophists have studied. They consider this to be limnal phenomena, on the border between the physical and etheric. It is a skill that must be learned, to perceive this invisible phenomena. Right now it's done with external monitoring equipment, and mathematics, then rendered visually.
Otherwise, you build up a new organ to perceive them directly.
Comments
http://www.amazon.com/Origin-Consciousness-Breakdown-Bicameral-Mind/dp/0618057072/ref=pd_cp_b_2
I've read bits and pieces, years ago. Barfield himself recommended it to me (I corresponded with him between 1988 and 1992). He mentions somewhere in his writings that if one ignores all the bits about the brain, the book is pretty right on.
FWIW.