An interesting essay by theadvancedapes.
Some related thoughts:
I was trying to make a point about the intelligence the other day where I riffed on Plato's 'shadow figures on the cave wall' allegory. One interesting aspect about the allegory, is the recognition of the shadows as figures. There's a circular nature to the knowledge in the experience, regardless of the subjectivity. To make the point, I suggested that instead of figures, we imagine that the shadows are prose.
In Cadell's essay, he mentions the warping of spacetime. It always struck me that the warping of spacetime by gravity is presented as a model that requires gravity to explain motion (orbs traveling on a surface distorted by their weight).