Ki is the dynamic of oscillation
Mochizuki Sensei specified that ki itself has both yin and yang and that aiki to can be either yin or yang. In either case, I think it would still be a combination of yin and yang.
Please comment more on this.
or the equivalent coinciding or alternation of opposing balanced complements -- of ... pretty much anything. It is a wholly different WAY of categorizing form, action and potential, than the western force-mass categories. Even though they often treat the same subject matter, they do not map onto one another at all -- but there are points of connection. It is completely intelligible in its own terms -- but the connecting point to western physical categories is understanding coincident complement forces/stresses and oscillatory dynamics.
There is one physical action that exhibits simultaneous yin (compression/contraction) and yang (tension/expansion) -- a shear. In shear -- tension and compression act at the same time and at right angles to one another. Shear occurs in bending stresses (in a plane) -- or more generally and more interestingly, in torsion, where they form a dual-spiral relationship around and strongest at the perimeter or skin of the object. See image: https://picasaweb.google.com/lh/phot...eat=directlink
If one projects these torsional yin/yang, compression/tension shear stresses in three axes of space you get this: https://picasaweb.google.com/lh/phot...eat=directlink
This is basically a six-directions diagram with the "windings."
Without getting into higher maths-- the potential of rotation (stress) and actual rotations are equivalent and the center of rotations can move around in counter-intuitive -- but understandable ways. This the reason for the illusion of the bendy pencil -- your mind tracks the oscillating center of rotations in the object more than it does the object itself and as the center moves the pencil appears to bend with displacement of its travelling center of rotation. This is directly witnessing ki applied to a rigid object -- and in which your perception of the ki dominates over perception of the actual object to which it is applied. The "feel" of ki in potentials (versus actual) rotations with the kinesthetic sense within the body or any connected body is similar.
The ki, in IP/IS, is used to "feel" within the body without having to have some nerve impulse. The mind can detect both nerve impulse and the "feelings" of ki. Usually, people believe that it is the mind that is feeling, but it is not. The nerves feel and the ki feels, but the mind can only receive the impressions from those feelings and it organizes that information and takes action on it.
Ki -- in the sense that I assert it, is a field quantity. If expressed in one part it is expressed in all parts-- unless there is a discontinuity. As a field quantity, what is felt in one part is felt in all parts. At a discontinuity - the field reflects itself -- which is a oscillation pattern, and one can learn to feel the orientation/placement of that reflection at the discontinuity. It is very hard to describe what it feels like -- a sense of a freedom to rotate (either folding or unfolding) and/or displacing the location of the freedom to rotate, inward or outward.
On the relation of these harmonies, this is great and succint description.
A straightforward and matter of fact discussion.
The three external harmonies are:
the feet harmonize with the hands
the knees harmonize with the elbows
the hips harmonize with the shoulders
The three internal harmonies are:
the heart harmonizes with the intent
the intent harmonizes with the qi
the qi harmonizes with the strength
This progressive inward or outward displacement of location of rotation or the freedom to rotate I associate with these three external harmonies -- since they all track the proximal/distal coordination relationship as the body folds/unfolds or twists/untwists inward to the center or outward from it.
On the internal harmonies -- I take it thus:
Heart (xin) harmonizing with mind/intent (yi) -- directs action to reflect all action -- not to anticipate and not to react -- depending more on initiation by reflexive faculties and not by conscious direction;
Intent (yi) harmonizing with qi(k)i orients reflective/reflexive action in-phase or out of phase -- but WITH the oscillation or potential freedom to rotate -- and never directly trying to oppose the displacement itself -- and to its limit until it naturally reflects and reverses phases at a discontinuity);
Qi(ki) harmonizing with strength (li) orients the pattern of muscular additions to the action to drive (or damp) the qi(ki) flow to greater (or lesser) energy exactly -- like pumping a swing (or damping it. This is the use of resonance or critical damping -- to generate or dissipate energy in the action.