As I've worked this Winter in my teeny tiny indoor, using concepts and ideas from When 2 Spines Align one of my biggest "aha" moments has been about the circle of energy/circle of aids.
I started off the Winter working on getting my powerlines correct(see previous posts about 2 Spines) and changing my biomechanics slightly to be more effective. Lots of hours went into using muscles that I hadn't been using and NOT using muscles I had been using. Also, the concept of the visual powerline has been particularly tough, since I love to look down and that puts my seat weighted to the front and of course puts Jet on his forehand.
So, anyway, lots of circles changing some habits and working on some basic things like simple transitions. The changing of biomechanics was hard but I could see in the mirrors and feel Jet being more correct, so that was encouraging, but I still was struggling with the concepts for half halt. Sometimes the half halts would be pretty good and sometimes not be effective. I kept struggling with what was different between success and failure. All the rides were good but some were so much more connected and balanced, leading to more complicated work that was easy. But what the he-double hockey sticks was the difference that made the difference?
After months of this and re-reading When 2 Spines Align I finally got it a couple of weeks ago. It's all about the circle of energy/the circle of aids. If the rider's powerlines are correct, if the horse is straight(relative to whatever figure he is doing), and the horse is forward, there is an almost self perpetuating circle of energy in every stride the horse takes. The horse goes forward from the rider's seat/leg, reaches to the bit and pushes away as he connects with the rider's connecting power line, and transfers his weight slightly back. Every single stride. In tiny almost imperceptible movements. Yes, there are stronger half halts which involve more forward or more wait, but it is the every stride circle of energy which gives the lovely and light carriage that involves the horse carrying himself easily. You know, like great riders do and can't explain. The caveat being, if the rider's biomechanics are even slightly off, the circle of energy does not work. The key for me personally was concentrating on my power lines in general and oddly enough, having spaces in my knee joints and my lats flexed. Who knew?
When instead of concentrating on "big" half halts every few strides and instead thinking about every stride using the powerlines to make Jet have carriage I wanted, with straightness, and a couple of forward half halts before any transition, I started getting the best work ever. More about the "big" half halts to come, some interesting revelations there as well.