Spinning Babies Perspective

Spinning Babies is not a method. Spinning Babies is a way of looking at childbirth.
Here, I see the mother and baby moving together as partners in birth. That makes sense, they each have a role, a choreograph or dance step to do in the birth process.
When baby is lined up with the pelvis, labor proceeds spontaneously. What do I mean lined up?

When baby's back is curled towards the front and