Amazing dressage lesson

Duke had his hocks done last Thursday, so he had Friday and Saturday off, a hack (at the walk) Sunday, light ride Monday, and increased ride with 20 meter circles Tuesday.
John started us by "breaking up his neck" where he holds his neck stiff at the base.  I opened my inside hand, used my inside leg just a little to keep him from collapsing in too much, and then as soon as he bent his neck, used inside leg to leg yield back out onto a bigger circle (and released inside hand).  If he tried to bulge out through the outside shoulder, I used outside leg to keep him on the circle, moving in.
If I couldn't break him up, I'd either do a couple steps of counter bend, or move his haunches into the circle with the outside leg.  Then, when he gave everywhere, we'd ask him to go forward a little (both legs on-off-on-off even) and John said he could see a difference in the trot (I could feel it) where it was more "swinging".
We did this, took a break, did it again, then did the other side, a break, did it again.
Then we moved up to trot, doing it again, and then canter.
John had us change directions through the circle, and then he did this absolutely amazing thing, where I could FEEL Duke lift up his inside shoulder (John said that was his hind leg stepping under), which was really cool.
Duke tried to figure out what I wanted, and tried to do it.  It was pretty awesome.
But what was amazing was not only could I feel him go round, I could get him to do it.  John had to talk me through it, but I didn't have to have John get on him first to get that amazing feeling.  Very very very cool.