Another thing found in Xenophon
When he was describing horse's conformation, he wrote something like... that the horse should move like a cat, or a wolf, or...? Well I have to read it again because I don't remember exactly. But then, on another forum (ESI) there was a short discussion about Akhal Teke horses and their "strange" way of moving; "like a hungry wolf on a cold night with a long way to go". It was then sayed that when you see a horse which "walks like a lion and trots like a wolf", it's a great muscle physiology and neurophysiology, no matter what breed.
Sorry for the metaphots but I don't know how to describe it
I remember such a horse, in one stable where I used to ride. He looked like very flexible and relaxed, like if he could move every part of his body separately, in every direction. Once he spooked when i rode him and I almost haven't noticed it! I haven't lost my balance even for a moment although he moved fast sideways and made half of a spin... if you know what I mean
in general no one ever lost balance when riding him, no matter what he did, and it wasn't collection; he was relaxed most of the time.
I'll try to read it again in Xenophon because I didn't find it important, only now when I saw the same written about Akhal Teke.
(by the way, thanks everyone for your informations about double back, it was very enlinghtening)