People! I know this is weird but it's facts. I have emphasized this in several book but not sure anybody has glommed onto the reality of it. In my latest book AXE, I show a full body energy diagram. In that pic, I point out that the ARC power follows the normal schema of Activate (dantian), Rebound (off soles of feet), and Catch (in hands). It's a full body traversal.
But what many people haven't quite taken on board is one phenomenon that other authors/teachers have rarely called out explicitly, though its obvious to any experience player, and its implicit in all energy traditions. But I want to emphasize the totally tangible, fully experiential reality of the following:
As the energy rise through your torso and back, it comes up unified: yin and. yang twined together, until the big torso wave hits the lingtai (spine about between shoulder blades). At that point the yin and yang currents split up. The yang (hard wave) current will go no higher than that lingtai branch point. (in the martial arts tradition that is. In esoteric yoga training, if you don't do it right then... things can go off the rails, but I don't teach those traditions. The martial arts version is safer lol!)
The yang goes forward through your torso straight into the heart center in the front, and it also kind of wrap around your upper torso beneath armpits to all reconnect at front/heart center. Meanwhile though, and this is the point of this post, the yin current continues upward, through the neck to and through the back of your skull, permeating the brain with a special affinity for its own original source socket (niwan 泥丸) at brain center and continues to project forward. For example when you're standing in Xingyi's classic static stance (really a dynamic process task, cf. AXE book), then the power will flash-permeate your FOREHEAD. Actually, your entire face.
But it's in the forehead as the largest and smoothest planar area of your face that you'll really FEEL it! Yes, I said FEEL it. This is how you know you're doing Santi correctly. Not at first of course, but eventually if you work to rule, at some point you'll realize HEY MY FOREHEAD JUST LIT UP! It's absolutely unmistakable. It's like a hot radiance or smoothed electric change went on there at the moment if comes through from the center brain (kind of a projective beam like an old fashioned movie project in the back of the theater lighting up the large flat screen in the front).
And within a second of your forehead lighting up like that, you'll get the payoff which is that the yin power has now broken through and is free to wash down your whole face, neck, collar bones and stream like a mighty torrent into the heart center where it reunifies with the yang current and together they blast outward through the sides of your torso and your upper arms, flowing from there into your forearms and hands or fists.
Note that I'm to talking here about the 3rd eye or anything like that. Tha t3rd eye stuff is fine (usually represented as a point by the way, not a plane surface as here) not denying it but what I'm discussing here is something particular and specific to martial arts that's really hugely super interesting once you get it going.
YOU WILL ACTUALLY FEEL THIS AS IT HAPPENS. It's not a concept, idea, theory, philosophy, metaphor, image, analogy, or any such.