Ignatius Teo wrote:
Instead, consider.... What makes the long bones move? What causes the body to stabilize itself? What happens when the body is under load or acted upon by a (linear) external force? What difference is there, if any, if the body is relaxed/tensed in that circumstance? How do you redistribute the load/force on your body so as not to stress it structurally? How does the "unbendable arm" thing REALLY work?
When someone pushes against Tohei's (for example) forearm, his chest, his shoulder, etc., he essentially lets the lower-body/ground handle the responsibility for the push. That is, he allows the body to form a path to the ground (this is the mind-body thing), so his body musculature doesn't have to do much more than maintain the integrity of that path. As a result, Tohei's body doesn't present as much of a moment-arm (lever arm) to the push and he's very had to push over.
This path from the push to the ground or the ground to the push (depending on how you look at it), is the essence of Kokyu. Kokyu-ho-dosa, Reiki-no-ho, etc., essentially practice moving this path through the arms while trying not to use the arms.
The "Unbendable Arm" is supposed to be simply another example of bringing the ground someplace, in this case the arm. If you push down on my arm, you're going to feel the ground, as purely as I can make it. The Ki Society may say something about a hose and water, but their visualization will bring about the same "ground" effect, for the most part. [[Incidentally, I have never liked the 'unbendable arm' demo because there are 3 or 4 ways to do it wrong and still think you've got it. I tend to avoid it because it's not a very definitive demo.]]
The interesting thing to note about the Ki-Society, IMO, is that while they use different terminology and different visualizations, they use the same principles and effects. As David Shaner Sensei began to try to give more detailed descriptions of what was really happening in some of the Ki-experiments, he easily and obviously overlapped metaphors and analogies a few times.