Greetings Andrew and Bob,
Bob. thanks for jumping in. I agree with almost all your thoughts.
Andrew, thanks for taking the time to clarify your views and your understanding further. Clearly you have some experience and have put thought into these issues.
I think I understand much better how you see and understand our practice. Your inquiry has also led me to pull out my DVD and verify that Master Yang Jun was doing what I thought he was doing. As for Yang Zhenduo, I do not recall any more how he did these transitions at the seminars I attended, although I thought he used more or less the same method. Since I no longer have much access to him to give clarification, explanations, and corrections, I now use Master Yang Jun as my model in almost all cases. The only thing I am still somewhat unsure about is how exactly you would prefer to do the transition and whether it is a matter of angles, distance, or touching the foot down. If there is a video clip you could link to and that would have someone performing the transitions as you would prefer, it would be helpful for me to see.
I do not recall that we actually use the term "circling step" in our teaching, but what I mean by it is that whenever you take a full step, you should usually choose a path for your foot that curves closer to the other foot when you pass by it. For me, it is important that I think of "closer," rather than "close," since circumstances will dictate the actual path of the foot.
I realize that there is probably no way to justify the way the Yang family makes this stepping transition other than to accept it as part of the family's tradition. I am working hard to match the traditional form in every detail, and will continue to perform the transition from withdraw and push to single whip as demonstrated by Yang Zhenduo and Yang Jun out of respect for the continuity of the family's teachings.
I think you may profit from opening your mind even more, rather than settling on tradition as the sole justification for this practice. I train in precisely this way, and this is the method I use quite comfortably and effectively even in spontaneous moving step. I am not sure I could have gotten the same skill using another method.
In contrast, many Yang stylists perform this transition with a definite withdrawing of the left foot close to the right foot in a temprorary "cat stance", just as you stated in your post. To me, this centering of the left foot provides the opportunity to move into any direction prior to implementing the single whip, in case a different posture or a different direction is indicated. It feels very comfortable to me and makes the transition to single whip more fluid and lively.
What we tend to say about such views is that there are always advantages and disadvantages to any approach. For instance, if you are talking about using angular movement to form a temporary cat stance at the angle, this has the advantage of flexibility, but the disadvantage of being slow. Stepping directly with no centering movement at all has the advantage of being quick and helping to strengthen the legs, but the disadvantage of decreasing stability and creating awkward Jin flow. Where some practitioners have one direct stepping technique, you are positing two.
I would say that we take a middle position in this case. We use one in
direct stepping technique, rather than one or two direct ones. If there is a lot of time or the angles are favorable, our moving foot will come quite close to the standing foot, approximating the movement of those that simply bring the moving foot in first. If there is little time or the angles are unfavorable, our curving movement can become straighter and straighter, approximating the movement of those that have one direct movement.
To make this distinction even clearer, as you claim that the Yang family does "center" the left foot in this transition, try finding a point during the transition from the fully-weighted right leg to extending the left foot in which you can comfortably lift the left foot off the ground and suspend it for a minute or more. If you can't do so without withdrawing the left foot further in, then I would have to say that there is not a true centering of the left foot in your transition.
I agree that having the leg in is more stable than having it extended, but this is only one principle.
Consider "Seek stillness in motion." One way that I try to respect this principle is to try to feel that every moment in a transition is like any other and that I have nowhere that I must go. If I must bring the leg in, this means that I am uncomfortable leaving it out and am no longer treating all positions with neutrality. What if I need to leave the leg out in order to stick to my opponent's leg? Or hook it? Or step on it? Depending on circumstances, the best path for my leg may not be straight in and straight out in an angular way.
I offer the same challenge, this time with the right foot, in the transition from "ward off left" to "ward off right". When I was training in Yang style long form many years ago, my teacher would have us do "holding rounds", in which we would hold the center position of each transition for a minute or so in order to fully distinguish between the empty and full legs.
I can see how this might be good training, but I do not think it would train me in how we distinguish full and empty.
Speaking in plain English, I would say that distinguishing full and empty in terms of weight involves having full control of momentum. To train this, we perform the empty-hand form so that it is clear that momentum plays no role in most of the stepping techniques. I test this, not be asking students to hold a position for long periods of time, but by spontaneously asking them to freeze for a moment. If they cannot freeze at a touch, then I would say that the are not in control of their momentum. A good time to test this is just before a foot is about to touch the ground or just after it leaves the ground. It is not necessary to freeze for long, since freezing for a long period tests other abilities than control of momentum.
Consider also "Continuously and without interruption." While Tai Chi movement is made of different components, stressing their differences tends to weaken their sense of unity. If you look closely at Master Yang Jun's final left step into Single Whip (from Grasp Sparrow's Tail), you can see one curving motion with two elements. For me, this shows in microcosm, Yin and Yang united in Taiji.
There are times in our weapons forms where we do bring a leg in and step immediately back out in the same direction, but here we discourage a complete transfer of weight to avoid a break in the Jin flow. In other words, after developing control of momentum in the hand form, we want to begin using momentum in the weapons forms. Thus, the same principle has a slightly different expression in the two classes of form. You can see the same compromise in action in observing most people perform the form using low stances. In order to stretch the legs as far as possible and get as low as possible, they tend to carry slight momentum in their steps.
I should also say that we do not distinguish full and empty only in terms of weight. When it comes to push hands or more advanced practice of the hand form, we talk much more about full and empty in terms of energy. I have talked with practitioners who have been trained to think in terms of 100% and 0%, or 99% and 1%; and they often have difficulty understanding our view of Tai Chi theory. For us, these percentages have little theoretical importance, whether we talk of weight or energy. In other words, regardless of your weight separation, you can have insufficient control of momentum and be double weighted. Regardless of your weight separation, you can and should still distinguish full and empty in terms of both weight and energy. The question is how to understand and how to train this.
I would like to respond as well to an additional comment you made in your reply to my original post, regarding "central equilibrium." With all due respect for Yang Jun, I do believe that central equilibrium is one of the five steps and can be performed in transitions and not just at the conclusion of each posture. Many Chinese Yang stylists emphasize this center position within the transitions.
I may not have expressed myself well. For me, "centering" and Central Equilibrium are not the same thing. Nor would I say that we have no interest in a "center position." We move toward the center, but do not require that you reach it or that you pause there. In other words, if we are moving between points A and C, we do not want to insert a new point B, even if that is a nice point to be at. We do, however, want to choose a path to point C that best balances speed, stability, and flow. As for Central Equilibrium, let me explain more fully.
In English, we talk about "steps," but the Chinese does not do so in the same way. The Chinese word "bu" (步) can be translated "step," but also as "stance" or even "footwork." Some also talk, especially in English, more about left, right, center, etc., but we talk more about the word in the Chinese doublet that indicates the quality, rather than the direction of movement: e.g., gu
("beware" or "take care of" 顾), pan
(" anticipate" 盼), or ding
("settle" 定). We would say that you want to be "settled" everywhere in the form and have stability; however, if this is all you say, you violate the theory. Sunzi tells us that if you always do something, you actually never do it. Taiji requires change. We must try to have full and empty even in this.
You seem to want to respect Central Equilibrium (or Settling on the Middle 中定) by inserting a new stable point between every pair of stable stances. Consider that such a point does not occur in every transition, and therefore there would be no way to practice this principle in every posture. We see the need to stress this principle just after you send your energy out at the peak of every posture and your Qi is necessarily up. We want practitioners to actively resettle the Qi, feel the Qi sink, and recapture the feeling of neutrality in movement that is lost in the feeling of Fajin. In my view, we focus for one instant on neither attacking nor defending, but rather on "settling on what is neutral." Although this idea connects with the energy flow generated by the legs, it is not dependent on moving the legs in any particular direction. It is not just an issue of balance, which is what the English word "equilibrium" might incorrectly overstress.
Lastly, let us consider the case of Ward Off Left. Here we move the left foot straight forward into the left bow stance. It would be more stable to move the left foot in and then out, but this would also have two disadvantages. By turning one motion into two, it takes more time and prevents you from learning how to do the move as one. Also, by losing shoulder-width spacing as you bring the foot in, you must now search to find it again at a difficult angle. By moving as we do, we tend either to move along the natural lines that frame the stance (which angular movement cannot do) or else move along the curves that approach these lines as natural mathematical limits (which straight movement cannot do).
If I had to summarize our method, I would say.
1. Step simply. If you need only to reposition your foot, just do that (e.g., right leg in White Crane Spreads Wings or the right leg moving into the third part of Fair Lady Works the Shuttles). Make sure that you lift the foot off the ground and that you do not just pivot, because you want to show that you could have stepped if necessary. However, don' t actually take a full step.
2. Don't turn a minor step into a major step. If the distance to cover is small, don't make it overly long by choosing a circuitous path, especially if the overall flow of energy is already in line (e.g., the left foot moving into or out of Play the Pipa or the left foot moving from Part the Wild Horse's Mane into Ward Off Left).
3. If you must step, try to step in harmony with the lines of force you need. If you begin far from the line you need, "seek the straight in the curved" and curve into the line you need (e.g., the right leg in Lifting Hands Stand Forward or the left leg in Single Whip after Grasp Sparrow's Tail). If one foot must pass the other, from front to back or from side to side, try to choose a curve toward your weighted leg that will increase your stability as the moving foot crosses its line, rather than holding to a purely straight line (e.g., the left leg in Defect Downward, Parry and Punch). If neither of these situation applies, just step straight (e.g., the left leg in Ward Off Left).
I hope this is helpful in explaining our view of things. Hopefully others will step in if I have anything wrong.