Gao Style Bagua Zhang

That's one of the clearest and most straightforward explanations of the contrast that I've read. You should write more ;-)

I think there is merit in classifying specific practices. But in this case, it's a matter of taking verbatim what the teacher says. Luo Laoshi in his teachings here in the Bay Area has repeated numerous times how his system is fully focused on building skill from in the "outside in" to use his words. Repetition of long, extended postures, hundreds of applications done over and over, mastering raw movement and structure and power, and then applying the mind to refining it over time. He said, "once you have chi, then we talk about chi". The energetic, emotional, mental, etc elements of these arts are not part of the basic training. The focus is on building up the body so that the more nuanced, microscopic aspects of the arts can be accessed.

Kumar is on a different track. He teaches from the perspective of totally mastering the internal awareness and sensation of the smallest movements, indeed from standing. In a certain sense you can only truly begin to raise hands in Tai Chi or take a single step of the Ba Gua circle once you've gotten the 16 Nei Gung principles built into your system. In a very real way, the internal martial arts as Kumar teaches them all require the use of ALL 16 Nei Gung in order to be truly doing them. They are the four wheels of a car you need in order to drive. Until then you are just doing an empty form, polishing the paint on a car that can't move. He's yelled at me more times than I can count that the specific movements of the form are irrelevant and the the internal training of the nei gung are of primary importance. 

Now, there's no reason you couldn't make all of these nei gung connections while doing the Ji Ben Shou Fa of Gao style Ba Gua. And on the other side, the more you do Tai Chi or Ba Gua, even poorly, the more you awaken to the nei gung elements within them.

But to me, after training in these two systems every day for over 10 years, they are diametrically opposed. Which is why they make for such a fantastic combination!

Ironically, both systems REQUIRE rigorous testing, free sparring and fighting superior opponents in order to reach their full fruition. That's one thing both approaches totally agree on!

Just one man's opinion here, not attempting to define anything for all time, but this is how I see things at the moment.

What about classifying certain practices, instead of whole systems, as pre v post heaven? Is this the same issue as fire v water?

Didn't Dong Hai Chuan and others pass the system on this way to their students? A system's always going to morph based on the individual talents of those that pass it on and the talents of those receiving the teachings, but it seems particularly relevant to a system where "change" is the primary topic of mastery.

I find value in the distinctions of fire and water or inside and outside. Bruce has said before that part knowing what something is, is knowing what it's not. While the shared root nature of two approaches to the same method may become experientially clear at advanced stages of training, the relative comparison gives dimension and direction to beginning and intermediate stages.

Personally I find this distinction to be nonsense. I don't think Liu taught Bruce an orthodox system but rather developed a set of changes for him  specifically. Why is only open to speculation.

Well ...it's true of a lot of various arts...we judge from the beginning, rather than engage in it and let it inculcate, then perhaps (as to our particular bents) we can 'judge' it...but usually by then we will have passed on that need as well. Oh, and I enjoyed you synopsis of the Breathing was helpful. Perhaps a little more on linking with the Ling ...

Didn't Dong Hai Chuan and others pass the system on this way to their students? A system's always going to morph based on the individual talents of those that pass it on and the talents of those receiving the teachings, but it seems particularly relevant to a system where; "change" is the primary topic of mastery.

I find value in the distinctions of fire and water or inside and outside. Bruce has said before that part knowing what something is, is knowing what it's not. While the shared root nature of two approaches to the same method may become experientially clear at advanced stages of training, the relative comparison gives dimension and direction to beginning and intermediate stages.