A jump lesson that taxed my brain cells

John did some flat work on warm up with us, to bring Duke back to the level John ended our lesson with two measly days ago.  I rode him one day on my own (sigh).  But it was really useful, because instead of taking John riding Duke, then 30 minutes of explanation to me, it only took a "few" minutes (10? 15?) to get us back to being decent and round.  Because we were in a jump saddle, I had to think much more about pushing my lower leg and heel down, and then, to keep from rounding, zipping up my front.
We did some bending to the inside, and then using my legs differently, to get Duke both forward and then round.  I don't know why this is so hard, but it's nice when we get it right.
From there, we jumped a vertical, turned right, jumped it again, and tried to get the damn distance correct.  First I was looking down, then I was looking too far left, then I was gunning him flat at it.  When we finally got it, John had us change the line, riding around another fence so we had to angle it.  This I screwed up so badly I had to go over it a couple times with my eyes shut.  John wanted us to go forward way out, and I was trying not to pull him too much back in front of the fence.  Duke eventually figured out (himself) that it was easier to put in a stride than keep launching over it.
From there, we jumped an oxer, then an oxer five stride to the plank, then another oxer, then an angle - angle vertical line, then an oxer with a roll back right turn to a narrow (where Duke kept thinking we were going to jump a different fence), then John put them all together in a massive course and had me ride it immediately.  That's the part that taxed my brain cells.  Even though we'd jumped each "segment" of it at some point, when he strung it all together, I had to hold the course in my head (without watching someone else do it) and then remember everything about every fence.  So we got a rail at the second angled vertical, but other than that, it was actually a quite satisfactory ride.
So if I can just figure out how to ride each fence when looking at them the first time, instead of on the third or fourth try, we might start getting only one rail.
I also told John how my mom said my posture was better, and he said "not how much better your horse is going?", which is kind of a compliment from John.  I also asked him why it's so much easier to balance cross country, even though you're going so much faster, and he said it's probably because Duke balances back when I sit up and I don't have to use my hands to do it.  When I use my hands, he kind of braces against them instead of balancing.
He taught this lesson on a horse, but I knocked down the narrow (twice) and then the angled vertical, so he had to stay on the ground for a while.
My stomach has been upset (for what seems like two months), so I was not terribly enthusiastic about the lesson, but it was a really good one.  I felt like we had a really good ride.