I had some excellent experience on jury duty, sitting in a chair. Two things are important to me, sitting in a chair: sit on the edge of the chair, as I believe you describe (a chair with four legs solid on the floor); then, one foot flat on the floor with the knee at about a 90 degree angle, and the ball of the other foot resting on the floor under your tailbone, approximately. I sit this way all day at the computer, and have done so for the last twenty years.
My back is not straight, especially the lower back, for the most part. Workman’s comp came out to review it at one place I worked (management requested it, they were nervous), and they said fine. I can find absorption in this posture, which to me is like talking to the one who made this shell and letting it take me wherever. So to speak.
Cranial-sacral theory provides an excellent explanation of the importance of the crossed-legged postures, as far as I’m concerned, and that would be: they isolate the motion of the cranial sacral system at the sacrum so that it’s apparent. Activity in meditation is involuntary, but for me it’s important to remember that the fascia and ligaments can generate muscular activity without conscious intention, as they stretch.
Allopathic and cranial-sacral medicine both use dermatones, the areas on the skin where the nerves from the spine end up, as a means for diagnosing spinal dysfunction; standard testing is to run a pin head down the leg or arm, and see where there’s a lack of feeling, and there are charts that will show you between which vertebrae the nerves are pinched if you have a lack of feeling in a particular location. What this says to me is that if you have feeling to the surface of the skin all over the body, your head, neck, and spine are aligned pretty much correctly, regardless of how it looks.
At the same time, it’s my belief that in the lotus, motion of the cranial-sacral system at the sacrum results in activity in the muscles of the legs and pelvis, as feeling is opened or extended throughout the lower body. That activity ultimately returns to the bones on either side of the skull through the extensors, which travel in three sets behind the spine to the temporal bones on each side of the skull behind the jaw. As the temporals move the parietals on either side of the crown of the head, and the nerves that determine the cranial-sacral fluid volume rhythm respond to pressure at the saggital suture, it’s possible that a feedback develops in the cranial sacral rhythm. John Upledger talks about “still points”, when the cranial-sacral rhythm appears to cease momentarily, and the fascial support for the body rearranges subtley; he found that maintaining a slight extension on the bones of the skull was conducive to still points, but the individual’s own psychie and need were the real determining factors.
We all have anxiety around falling down, especially backwards. Look for motion side to side, around, and forward and back wherever consciousness occurs; that’s a sense of a physical place, the “wherever consciousness occurs”, which the zen masters aver we should attend to 24/7. Relax the activity in the three directions. Let it sink, if you feel good with it, remember that the stretch that generates activity doesn’t necessarily feel pleasant, but it doesn’t have to go all the way to painful if you can relax the associated activity and let the mind move.
Single-weighted postures have a built-in activity from the stretch involved as well. & blah blah blah as somebody so eloquently said!