Jonathan,
It's all weird to me! As I said in an exchange with Constantinos Ragazas on Steve Sax's page, I often wonder if mathematicians realize how phenomenal their memory capabilities are. I rely on people like you to gain some insight of what the myriad maths are about, and often find myself completely out of my depth.
Intuitively though, it seems that if the addition operation is short-cutted, a moderating value would be lost, and the butterfly comes out of chrysalis in the round, as one direction lengthens without restraint. I still can't grasp the morphology of quarternions and division algebras that project a 4-D shape, and lost track of where I read a post of yours about 3-D imagining being an approximation. Like many I suppose, I find the images beautiful and can only wonder how that fills space over time.
And of course there is the ever present counter-intuitiveness of QM that over-shadows just how counter-intuitive Relativistic spacetime is itself! I for one greatly appreciate that yours is a genuine kindness in patient explanations of the rudiments of mathematical physics, thank-you. jrc