Re: Defining Kokyu
I wish we could see the event in this picture from various angles. To me, it doesn't look like they are perpendicular to the Jo at all. The angle of the Jo and the differences in body positions between the Uke's makes me think the actual line of force is at a slight angle to the Jo's long axis. Numbering the Uke's 1, 2 and 3 moving outward from O'Sensei, I note that 1's hands are not equidistant from his center, but the hand closest to O'Sensei is in fact further forward, implying to me that the force is not truly "perpendicular" to the Jo. As you move to 2 and 3, the angles become even more exaggerated along the vertical plane as well as the horizontal. This looks a lot more complex to me than the traditional description I've heard which involves four Uke standing perfectly perpendicular to a completely level Jo pushing with all their force. Thanks for posting this image, it's fascinating.
This reminds me of something one of my sensei's showed me once. We were doing work on maintaining a strong center in seiza, and I was sitting on the floor with a partner pushing on my shoulders from the front. Although I could maintain my posture, it was a definite effort. Sensei came over and said "align your forearms under his and lift gently as you do this" and as I found the alignment he was talking about, suddenly the pressure redistributed and the whole exercise became easier. When my turn came to provide the pressure to my partner, sensei showed him the same thing and I was amazed at how well it distributed the force I was trying to apply. It wasn't mystical "Ki" stuff, it was utilizing leverage and body mechanics, though from the outside, it might well have looked like some kind of mystical power, as the change in position was fairly subtle. Looking at this image, I have to wonder if there is something similar going on. O'Sensei's lifetime of martial study had to have given him an immense understanding of the forces the human body can exert and the limitations of our physical structure.