yeh i've always been taught to bend the horse with my legs so that the whole of the horse is bending not just the head and neck, the track of the hindlegs should follow the track of the fore legs.
I've always been taught to bend a horse like this:
The horse should be moving forward positively maintaining balance, the rider should be balanced themself and be incontrol of the horse.
The outside hand should maintain a light contact allowing the horse to move freely so the horse can be moving forward actively.
The inside hand should be slightly open with the rider flexing the arm to great a slight bend of the neck.
The inside leg maintains contact at the girth to keep the horse pushed out and not falling in on the circle, the horse's body should bent around this leg.
The outside leg should maintain contact but be slightly off the girth.
Once the horse has started to bent and the rider can see the inside eye and nostril, both legs should be used to encourage the horse to bring it's hocks further underneath and th horse should flex it's topline.
The horse should then relax it's poll and jaw and should maintain the bent and be moving forward positively.
The rider should turn their head and shoulders inward in the direction they want to travel, keeping they're body relaxed but not dropping the shoulders.
That's how i was taught by my instructors hope it helps!!
anebel offtopic: but what do you mean by middle english text?