If emtiness is form and form is emptiness then body is mind and mind is
body. It is only our ego mind that judges, that measures and creates false
separation. Enlightenment is as much a physical process as a mental one
because physical and mental processes are not separate, one can never exist
without the other.
The importance of a straight spine in meditation is very fundamental. The
diaphragm, pelvic floor, feet and other membranes associated with “chakra’s” store trauma and memory in the body distorting posture and bending the spine out of shape. A spine with proper curves is the result of progressively undoing this storage of memory, hence the physical and mental consequences (karma).
If the spine is not “straight” the mind will not be straight. A “straight” spine actually means a spine with proper curves. This is a prerequisite to achieving the Jnana states or bliss states. These are themselves an essential prerequisite to achieving full understanding or enlightenment.
Meditators who sit for hours on the cushion with bent backs and twisted bodies, forcing themselves through will to “keep on at it” are hypnotising themselves and making no progress. They would be doing more for themselves, their practice and the world if they took up yoga, learned to breathe properly and went to see a chiropracter.