Steve, I agree with your posting about “Yi” (“Mind intent”). You make a good point about the difference between form and application. Let me explain how I see the unity in the surface meaning of what we both expressed, since I now realize that what I posted could have misled people. You are, of course, still free to disagree with what I say.
First, I think that most schools of Taijiquan take a progressive view of training. In doing form, our mind is directed to one thing; in push hands to another; and in defending ourselves from harm, to yet another.
While doing form, I believe that we are trying to become aware of how our bodies move, but are not trying consciously to move each part of our bodies individually. In other words, we are trying to develop a holistic feeling of how each and every part of our bodies should relate to a particular movement goal. As this feeling becomes stronger and stronger and more automatic, we reach the stage of intuitive understanding (“shenming”) of movement. At this stage, we naturally move during form according to the principles of Taijiquan.
At the basic stage of studying form, I think it soon becomes important to knit the movement of various parts of the body together by some method, what the authorities describe as “threading” the power/strength through the body, or the “nine bends of pearl.” I believe this is best done by always having a particular mind/body focus (or “Yi”) that gives meaning and purpose to the movement of every part of the body. This “meaning and purpose” is not only realized at a particular endpoint within a posture sequence, but operates during the transitions as well. When one has an intuitive understanding of this, I think one no longer needs a conscious awareness of this and “shenming” (“intuitive understanding” or "spiritual illumination" or "enlightenment") takes over.
For example, in doing Ward Off in the form, I think one has to have a strong mental focus on the proper Jin point in the forearm. In Push Hands, however, I think one begins to leave this feeling in the background and instead progressively puts one’s mental focus into sticking, adhering, linking, and following. Once we begun to understand how the skills relate to offense, defense, and controlling our opponent, we can them use them intuitively during free-style movement. At that point, we can begun to focus our “yi” onto higher level concepts, like “forgetting oneself and following the opponent.” This is what I think you were in essence describing in your post.
I have gone to some length here in order to tease out what I understand to be some of the differences between these levels of training. I believe some practitioners too readily want to skip the basic practices and can unknowingly limit their ability to progress. (Just to be clear, I do not believe you are one of those or are advocating this.) Some seem to focus only on “relaxing” and doing what is “natural” and expect everything else to fall in place without further mental effort. I even know of some people who advocate doing form in almost a sleepy or trancelike manner, which I do not believe is appropriate for traditional Yang Style or the traditional training regimens.
Psalchemist, you asked me about “internal movement” and “synchronicity.” What I was trying to express is that talk of “moving the body as a ‘unit’” is ambiguous. I believe the classics advise to move our limbs with “one qi” (“one energy impulse?”), not really to move everything simultaneously.
Consider how we clap with two hands. Is this really one action, or two? If someone grabs one hand half way through a clapping motion, do you have to struggle to prevent the other hand from completing its motion? Does clapping require that the distance each hand must travel be carefully controlled or that the speed of both hands be consciously monitored? I would say not. Clapping is a natural motion that does not require conscious control of the individual parameters to have control over the action as a whole. We can naturally, effortlessly, and instantly modify our claps in all sorts of ways, as long as our minds remind focused on the activity of clapping and not on other aspects of the hand motions.
My argument is that movement in Taijiquan should have the same qualities as clapping. In my view, one does not practice form to get better and better control of individual body parts to ensure greater and greater synchronicity; instead, one practices to understand or to feel more and more deeply how the various parts of the body can form “one qi.” The synchronicity is merely a byproduct, but it can also function as a diagnostic tool.
When your opponent touches you, you do not change only the part of your body that is touched. Instead, you change your entire body and spread the degree of change over all your body parts. You do not will any part of your body to retain a previous state unconnected with the “one qi” that is now required by the external change.
The “one qi” must be created by your mind. A clap becomes a clap because your mind imposes that framework on your palms, not because your mind independently metes out the force required for each palm and measures the distance to the point of impact. Similarly, your “waist” guides the movement of your hand because your mind feels the connection between the two, not because your “waist” and “hand” happen to be simultaneously in movement. You do not really predict, estimate, or memorize the amount of motion necessary for each to arrive at the appointed place and with the appointed force.
To point it simply, I believe that those who do form well look as if they are engaged in a feedback process that makes them continuously reinvent how they move right before your eyes, rather than merely redisplaying motion they have fixed into their muscle memory.