I don't think Homer (for example) ever talked about "maintaining your spine angle" tho....
He wouldn't have to if the head remains steady and the eyes are fixed on the ball. The eyes would, as Lynn teaches, monitor any movement off the ball.
Homer does write about the four snares- bobbing being one of them.
But what Annika will explain is that while the head remains steady- the spine adjusts itself during the pivot.
AND... you would never know it until you see/understand how this study explains what the spine does in a pivot. Another notch in our development of knowing what the golf swing is all about.
The 4 sections change. Something to do with Pitch, Yaw and Roll, if I remember one of Annikans earlier posts correctly.
The spinal column is rotating in a diagonal or oblique plane which is a combination of those great pics!.
I think from down the line view many like to draw a straight line to represent the spine and its angle. And I think, no real knowledge that although that is nice and maintaining the angle from down the line seems to make sense to me, the spine is not a straight line and in order to accomodate rotation and shifting, parts must be in motion.