Perceval said:Several of the recent circles seem to be designed to encourage viewers to conceive of shapes in 3d, or maybe 4d!
That's very close to what I was going to say. They recently started using two-point linear perspective to draw "3D" CC's. That's the second one after the "Danebury basket", but as for me, the breaking point was the Whitesheet CC which is one of my favorite CC's. It reminds me mercury (lively/quicksilver) and seems to getting ready to jump out of a 2D plane. That's utterly subjective and doesn't make much sense, I know, but that's how I see it anyway...
Can't wait to see where they are going to take us with their dimension lessons! :) Not to mention the historical/geological aspect that is very mysterious as well...