Since you’ve studied this scripture perhaps you can share your insights with the rest of us so that we can get a clearers picture of your perspective. The thing I could see the in common between the one finger zen training in hung ha and wing chun is the rooting and waist twisting/torquing mechanics to generate spiralling force from the ground up. Is that what you’re referring to?
Basically, yes. Coiling, rising energy, but there's more to it than that.
I've got a whole set of notes in front of me dusted off so I'll just select some highlights. Under "Dragon": the sum faht of "soft within hard", the Tang Toe Earth movements of swallowing and spitting. The Five Animal Fist second section contains Southern Dragon Fist methods to "steal and leak itno the oppoent using coiling and twisting of the body, blocking and striking with the elements of earth, while invading the opponent's space". These are the same basic elements of Wing Chun. Short range striking, but also short range grappling.
Dragon has claws, unlike Snake and Crane. So, I often wonder, why do so many Wing Chun students forget they have 10 fingers. Always crossing arms, chopping, striking, punching. It's the truly advanced Wing Chun students who find the Dragon and start ripping. Ask Alan Orr.
The common thing between the bridge and mechanics is how the animals are described in Taoist/Buddhist literature, because that was the framework in which the style creators worked. None of it was by chance. Taoist and Buddhist imagery and concepts were the common language of the people who met and interacted and codified things, so when you read a lot of what's been written about the Ng+ Ying styles over the centuries, the techniques when described in writing are rich with symbolism that clarifies a lot.
This is what expands beyond just Hung Ga Kuen as a specific grouping. Let's consider Li Ga, and how Bak Mei surfaced, right down the road. Southern Dragon motifs all over these. Everywhere, really, because "Dragon" is how they referred to old, strong people back in the day in Canton.
It might not jump out but if you read Tang era poetry about dragons (I'm that big of a nerd), or scholarly research into Wing Chun, it starts to knit itself into a big pattern. These scholars below (from Cornell) wrote about the connections between Southern Dragon, Wing Chun, other family styles.
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