Re: Restart on Jin/kokyu and "Spiraling"
Well, those are good points so let me try to re-state while keeping in mind that my focus was on the linearity. I tried to save time, but yes, let's get down to finer detail.
First of all, the real point is that there is a linear aspect of jin that goes from the dantien to the opponent. That's the main point. In many cases and many styles people deliberately hold the elbow down so that there is a clear channel from dantien to elbow to hand because it assists in the conveyance of the force (less stress on the joints).
In terms of the lines from the ground, I had a choice in terms of physics: I could say that the ground powers the dantien (the hip part is there, but let's simplify) and the movement of the dantien is the main power of the jin that connects with the opponent. OR I could say that the body as a whole works as a singular frame (this perspective is also a valid viewpoint) and the actual jin is a vector resultant that starts somewere below the dantien. Either way it's stated, though, there is a *linear* force on the opponent: that's just basic "jin", which I've actually heard native Chinese describe as a 'force vector'.
'Spiraling' may or may not affect the *power* of the jin, depending upon how it's done, but whatever effects spiraling may have they are apart from the core jin itself. The jin is a linear force.
Is that clearer?