"In physics, spacetime (also space--time, space time or space--time continuum) is any mathematical model that combines space and time into a single continuum. Spacetime is usually interpreted with space as existing in three dimensions and time playing the role of a fourth dimension that is of a different sort from the spatial dimensions.
" - http://en.wikipedia.org/wiki/Spacetime
As long as you continue to envision one point as space-bound:
the meaning of the phrase "keep one point" will elude you. All of your questions regarding "keep one point" are centered around spatial characteristics. All I'm asking is that you put aside trying to figure out what one point is and consider "keep one point" from the point of view of how the phrase relates to the temporal relationship between mind and body.
So now you have me wondering if what you mean by "keep one point" meshes with some concepts from, umm, stuff outside of Aikido I have encountered elsewhere.
The concept, from bird's eye view (and perhaps the bird has cataracts): say I want to make a circle, I must forget that I am making a circle. At each moment, at each point (in space and time), I am just trying to make the best linear forces I can. I do not scatter myself to a bunch of different directions or where I want to go or where I was. Rather, "here" I am, and I try to be the best "here" I can be. But, woops, no clinging to that moment, by the time I recognize that moment, forces that I have exerted have put me somewhere else. The next moment has come, and I am somewhere else, and the relationship of me to that circle I somehow happened to be making has now changed. I must then be "here" again, and "here" has changed, so the linear forces I am dealing with must necessarily have changed. Any conscious analysis/clinging to something/thoughts will just totally screw it up. Reality doesn't take breaks while you stop to think, so you can't stop to think.
It's basically a feedback loop between awareness/observance of the goal and the moment-to-moment optimization/course correction that effects that goal. It's a state of mind that is recognized, isolated, and trained to deeper levels.
Another simple example where this state can be readily observed: when boxing, at the exact moment you launch a strike, if you only focus on striking, that is the exact moment when you are the most delightfully punchable. You must simultaneously be reacting to the possibility of getting hit even as you go to hit the other. Just another manifestation of the simultaneous mixture of awareness and action...
But, that's another thing from another art. But is it a cognate of "keep one point", false or otherwise?