"'We are therefore often unable to achieve our goal with normal snaffle work alone, or we reach it after a long detour and much more time.
'A horse with a weak neck that is carried too high, with a raised nose that is poked out, bends the neck incorrectly right in front of the withers. The neck evolves into a ewe neck. The poll flexion and the snug position of the saliva glands against the neck muscles is omitted. A horse with a stiff, high neck and head exercises his strength against the haunches immediately and oppresses them. Individual body parts suffer therefore even when the rider is just cruising around, without working the horse. The modest and correct application of an auxiliary rein, on the other hand, will soon lead the horse to assume an appropriate posture.
'The auxiliary reins must in no case be used to force horses into frames. They are merely supposed to give the horse a limit that he is not allowed to exceed in trying to get out of postures he is already able to assume. And they are supposed to improve these postures gradually. They should teach the horse that the posture within this limit makes it easier for him to move.
'The horses are easily convinced and obey modest and correct demands that we can increase according to the progression in the training.
'Some riders train difficult horses without auxiliary reins. They expect and achieve success in part through time, and in part through their rein conduct and their seat. E.g. in the case of horses who raise the neck and stick their nose out, they carry their hands very low on either side of the neck and lean forward very much, trotting this way with the weight on the forehand until the horse drops his head and neck, trying to find support for the forehand in the reins. Then they lead them back into balance.
'Why weight one part more for a time, cause an incorrect saddle position, why assume an incorrect seat (which is not applicable in military formations, anyway), if we can reach our goal more easily and quickly with the appropriate use of an auxiliary rein.
'Auxiliary reins must be used with great care and tact. Applied appropriately, they have multiple advantages. Applied ignorantly, tremendous disadvantages.
'Auxiliary reins serve the rider not only as a support in improving the horse's posture. But they briefly lend the horse a support that he could not find in the rider's hand alone in many cases, when the neck is weak and limp, or when the haunches are weak, and he would otherwise lose his posture entirely.'"
(1837; translation: T. Ritter)