A good explanation, however one small part is exactly backwards:

"If CBM is an accurate description of a body reaction then the action that produces CBM is 'body swing'"

This is incorrect - CBM is the first action, which is in turn followed by swing.

Further, CBM and swing are actions, while CBMP and sway are positions, that may often result from these actions, although they do not always, and there are other ways to end up in those positions.

Anonymous,

Obviously I disagree with your point of view that 'CBM is the first action, which is in turn followed by swing'.Also, your point of view is the single biggest misconception about CBM. But I'm glad you brought it up because it gives me a chance to elaborate on how I understand CBM.

I'll explain exactly why by elaborating on my previous reply.

Firstly you seem to imply that the concepts 'swing' and 'body swing' mean exactly the same thing in the 'ballroom' context. While they are closely related ideas they have subtly different meanings. 'Swing' is commonly used in a more general and loose sense. We all dance Waltz or SlowFox with 'swing' whether it is good 'swing' or bad 'swing' is another matter. In fact it is possible to produce some sort of 'swing' without CBM or a pretty distorted idea of CBM (though many of us would regard this as very unattractive).

The concept of 'body swing' is used to describe 'swing' that is produced or created in the way the I described in my previous reply ie. usage of ankle/knee/ hip joint in combination at the commencement of the movement to get the one side travelling faster than the other and produce an early rotation within the frame, etc, etc...(read my previous reply). The essence of the 'body swing' idea is that CBM is not a separate action preceding 'swing' but rather, for it to be applied and danced correctly, it must be an integral part and product of the very swing itself. In this sense CBM as a concept is an 'observation' of a reaction produced by the commencement of swing using the idea of 'body swing'. If you produce 'swing' using the concept of 'body swing' you are commencing your 'swing' in intent (mind) and action (body) from the very, very start of the movement. If you produce 'swing' using the concept of 'body swing' you will have produced the CBM reaction.

I believe that it is this way of viewing and applying CBM that enables one to easily understand and apply the CBM concept in one's dancing. A common mistake is to deliberately produce an action (vs reaction) of 'turning or rotating of the opposite side of the body towards the moving leg...' without any intent or notion of 'body swing' in the dancers mind. Additionally this action incorrectly originates only in the upper body (shoulder action). What follows is a complete distortion.

I agree with you that cbm has to fall naturally into it's place in a downswing - upswing progression.

However, a simple energy conserving downswing-upswing will not include CBM. CBM requires that a rotational acceleration be produced (best thought of as the trailing side of the body encouraged to catch up and often eventually take the lead). This requires something propel that side of the body, and this something is the specific way you move across the foot while transitioning between 3 and 1.

Swing does not necessarily involve CBM,
however CBM taken between 3 and 1 will, when executed at the magnitude appropriate for most figures which feature it there, necessarily result in a particular type of swide swing over the next two beats. And it's that particular side swing that produces by sway around the latter half of 2/beginning of 3.

A person-sized rectangular weight swinging as a pendulum will not naturally exhibit the twising type of motion we call CBM unless something acts to twist it - swing does not cause CBM, standing leg action does. On the other hand, applying translation + CBM to this test pendulum would produce side swing and result in sway...

To further clarify the distiction of intent required to generate CBM, let me suggest an example for Quickstep.

Consider something like a progressive chasse followed by either a forward lock, or a natural turn, and how you would lead the difference. According to the ISTD, there is CBM on the first steps of both the forward lock and the natural turn, but the CBM on the forward lock is given as "slight" - very, very slight in fact, as this is essentially the only active difference between the first steps of these figures. When it says "commence to turn" for the natural turn, what it means is do that action that commences a turn - and that action is CBM. Wheras the forward lock would lack the feeling of commencing a turn, because there is to be essentially no turn over the figure.

Both figures commenced from the same position. Both land on the same part of the foot at the start of 1. But in one a strong feeling of CBM is included to create a turn, and in the other the CBM must be weak enough to not lead the lady into a turn. To me, this says that CBM must be an intentional parameter, which coincides with the free downswing, but must exist as a unique intent.

As a lady make sure you know the mans steps. As you complete the cross the man is on his two toes with his feet together on the spot Hoping to lower verticaly. Because of the nature of the step at the end your feet are crossed up. The experienced lady dancer knows that her next step into maybe a Open Telemark. The first step must not be taken under her own hipline, but out of it. Otherwise the alignment will be severly underturned. Then the wrestling commences followed by the argument.

I beg to disagree!

While the description of the man's part is more or less accurate visually, he will be standing on his right toe only. He must not have weight on both toes, or the lady will be unable to complete the couple's turn as she dances her cross. It's important for the man to neither rush nor retard the lady as she finished her action.

"The first step must not be taken under her own hipline, but out of it."

I'm not sure if you are referring to the first step of the double reverse, or the first step of a following figure, but regardless, the lady always steps under her own body on the first step, because she moves her body not her foot. She must never step with her foot alone while leaving the body behind. Failure to maintain the body in vertical alignment over the foot when entering a heel turn will result in off balance posture and a forcibly faked heel turn.

The lady will finish with her feet crossed. She must clear a path for the man and not occupy the space that he needs. Try the ladies step and see were it finishes. If you stay in that finished position and extend your right leg back under your body line you will have difficulty with, for instance a Open Telemark. Just try it.

"Try the ladies step and see were it finishes. If you stay in that finished position and extend your right leg back under your body line you will have difficulty with, for instance a Open Telemark. Just try it."

The reason you have to do this is only because you are approaching the action of stepping incorrectly. One should not extend the leg to take a step, rather one first moves the body and the leg swings naturally underneath it, without nearly as much specific effort.

Because the step features CBM, the hips will turn as the body is moved for the step. This provides sufficient "uncrossing" and means that the leg falls in the proper position, out of the partner's way. Any subsequent extension of the leg itself will go in the proper direction because the hips are already directed there.

I wondered how long before CBM came into this. It is exaxctly as i wrote. If you apply CBM unless you get into something like a Yoga position. Doesn't the leg alter its position in relation to the body Try it. This is happening all the time. Step four Spin Turn Waltz. The mans step will actually move to diag wall 'naturally .Whilst the ladies step goes down the line of dance.
For the man this is a very polite way of moving out of the ladies space', allowing her to swing past and not dawdle or be pulled through. Also ladies turn your head a little more to the left on step four making sure that your head arrives last of all. Try , if you don't like then dont do.

"If you apply CBM unless you get into something like a Yoga position. Doesn't the leg alter its position in relation to the body Try it."

When you apply CBM, the position of the leg with respect to the body does indeed change, but stated against this frame of reference it's very confusing. CBM requires that the orientation of the hips in the room change, but it does not required the orientation of the leg to change (yet). So if the hips turn and the leg goes straight, then the body-leg relationship has changed. In most swing dance figures, alteration of the actual direction in which the legs swing over the floor is not advisable until step 3.

From the lady's cross in the DRS, she can in fact step straight down LOD into another heel turn simply by using CBM to neutralize her hips. But even if you desire to send her more to DC to accomplish a lot of turn (open telemark ending LOD?) All that is required is that you send her body in the proper direction. We never send a leg anywhere on step one - we send the body, and the leg finds itself underneath.