image by Yoga with Horses & Linda Guanti
The bend I refer to is that of specifically the neck and generally the entire body. The bend is one of four factors I consider in the working of the horse, that are rules so to speak and guidelines. When something is not functioning properly, i.e. a movement isn't as correct as I would like, then I defer to checking on the four guidelines. They are, in no specific order, Bend, Posture, Speed and Balance.
Why bend is so important is because it is the basis of posture, and posture is how you direct the horse's movements. Posture is also how you affect the horse's speed and balance. So you can see they all go hand in hand. Bend comes before posture, because if you lose the bend or are obtaining it through force (and with force comes resistance on the part of the horse) and then attempt to create the posture to then direct the horse, it will not work as efficiently or may not work at all.
There are particular instances when straightening, and thus losing the bend, is appropriate. In between lead changes for example. If the horse has changed the bend away from you, he places you at a distinct disadvantage and in danger if you are on the ground. From the saddle you lose your ability to influence him with the reins in a predictable manner. It becomes more clear why the bend is so important as we look at the dangers.
Bend controls the direction the horse travels in, affects your ability to posture the horse which controls the speed that the horse moves forward, sideways or backwards, and the horse's balance.
Bend cannot be forced or coerced from the horse, but rather finessed. It takes tact, patience, timing and rhythm to develop and maintain the bend. It is the basic of rein aids and can be trained before the horse is ever ridden.
I couldn’t refrain from commenting. Exceptionally well written!