The translaton is simple, but the meaning is not! Geracerichtung means "straightness." But what does straightness mean to the trainer?
Early in a their training, horses tend to keep the length of their bodies an equal distance from the arena wall or fence, so if the shoulders are 1 meter from the fence, the hips are 1 meter from the fence. This sounds pretty straight, until you realize that the horse’s shoulders are significantly narrower than his hips! So a young horse in this position is actually quite crooked. What we really need is for the horse’s spine to be parallel to the wall or fence, or whatever line they are traveling. That is one facet of straightness.
The horse at the right is surrounded by 4 identical arrows and 2 parallel lines. The arrows on the left fit perfectly between his body and the line, the way a young horse moves along the wall or fence. If he were truly straight the two arrows on the right would also fit nicely, but they don't. The top arrow has extra room and the bottom arrow is squashed. This horse is not straight.
A problem with crookedness is that the horse's hind legs are not working equally. The horse in the picture has his left hind leg more underneath him, so it is providing more push. The right hind leg is taking it easy. Overall the horse has less power than if both hind legs were working.
When the horse is traveling on a bending line, like a turn or circle, his body should still follow the line of travel, his midline should be parallel to his path, and his hind legs should follow directly behind his front legs just as on a straight line. This requires that the horse’s body be bent. Bent IS straight on a bending line!
Biomechanics experts debate how and how much the horse actually bends his body, what degree of movement the horse is capable of between the vertebrae of his back bone, whether some of the feeling and appearance of bend actually is caused by tilting the ribcage so it hangs more to the outside of the turn, but all agree that bend is necessary!
Another facet of straightness has to do with sidedness. Just as you are left- or right-handed, your horse has one side that is stronger than the other. Straightness requires strengthening the horse with particular attention to making him equally strong on both sides, so he can perform equally well in both directions.
Ironically perhaps, the best exercise to develop straightness is circling. When a horse is correctly bent on a circle, his inside hind leg works harder. So work on circles enables the trainer to strengthen each hind leg separately while working toward equalizing the strength in both hind legs.
Since straightening a horse requires strengthening, this step is time consuming. The horse can only progress as fast as he can build muscle even with the best trainer. How will you know when he is strong enough?