There is variability, and then there is variability. When Miyagi Chojun chose to take Higaonna Kanryo's Fuzhou Sanchin and close the hands, he chose to bring a style down a very different path. Thus we have Uechi style Sanchin...
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...and then we have Goju style Sanchin
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There is no mistaking the two styles. And there is no mistaking that Miyagi Chojun turned his back on half of what makes Kanbun's style what it is. It was a choice, and he went far down that path - with no turning back
Here's the thing. What makes Kanbun's style special is like decaffeinated coffee unless you are doing some reasonable facsimile of this - virtually every single class.
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I used to be ambivalent to this kind of training, figuring I could pick it up in the weight room. But there's no way to develop the yin half of pangainoon if you don't develop the tiger's grab. In the book of Bill, a shoken and a hiraken is only half a weapon if you think only about poking and thrusting with it. In the book of Bill - and likely the book of Kanbun - the other half of Pangainoon was grabbing with THE EXACT SAME TECHNIQUES that you poke or thrust with. That's my story, and I'm sticking with it.
So I've been passively watching virturally an entire region of The New World being ambivalent about the use and placement of the thumb in Kanbun's style. Let me be clear... there's no ambivalence about the positioning of the thumb in jar training. If you're not doing this, just don't even bother.
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So... do you see this?
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Kanei isn't ambivalent about where he puts his thumb in that posture. Why? If you don't spend half your time in a Uechi classroom grabbing with your shokens and your hirakens - and these weapons have a very "special" effect when you correctly grab with them - then you're really going down a path of no return with Kanbun's style. Go far down that path and you cannot come back. Your mindset is altered. Your brain synaptic patterns are altered. Your physique is altered.
It's a choice.
There... I feel better now.

- Bill