...okay, I am not getting on with the problems I see in Steinbrecht's exposition of the side-passes. So instead of going into details of what bends when, were the feet fall, which aids to use to control what, all juxtaposed with an underlying mix of anatomical details, which does not count up, I went ahead and took a good look at the first few parapgraphs of the previous chapter, which is devoted to riding the horse on straight and on curved lines...
(1) ...every line a horse walks on is determined by the direction of its body... the horse, which is not bend thus will follow a straight uncurved line... the horse, which is bent will trace a curved line. The line's curvature will be equal to the degree to which the horse's body is bent...
...here the questions begin. The very problem of equitation rests in the fact that the green horse's body does not line up with the path it travels on. Asymmetries in its body will cause a decidedly different reaction to initial left and right turns. So why does Steinbrecht come up with this presentation, which describes an automobile rather than a horse... The horse, in liberty and/or under saddle, on the other hand, is very well able to turn in an outside bend and/or while turning rotate around its center of gravity. It is not at all bound to curvatures of its body for fast and successful turns... To the contrary...
(2)...a. ...the forehand designates direction, the source of propulsion, however, originates in the hindquarters... the more minutely one lines up with the other the better the horse's locomotion and posture will be... diversion of the forehand or the hindquarters from their line of travel will compomise both...
...again, many questions. What does he mean by the line up of forehand and hind quarters...? Certainly not that they must travel along the same hoof track...? More than once he declares the positive value of side-passes (i.e. diversion of shoulder's and croup from one line of travel...) and their role in the improvement of the horse's posture and locomotion...
(2)...b. ...a change of direction can originate in the forehand, or it can come from the hindquarters... It also can be the effect of both so that, for instance, in a right turn the forehand steps right, whereas the hindquarters depart to the left from the current line of travel...
...now here we go, this again is the Steinbrecht I love... Yes, the horse can turn around its center of gravity... and in fact this is the fastes and easiest way to turn...
(2)...c. ...depending on the choice of balance points the horse will support the turn more with the front or with the hind legs... and, as a matter of course, the part that carries more weight is less mobile, and hence will contribute less to the actual process of turning...
...hhm, ...now, ...wait a minute! ...Yes, most certainly there always must be a support ...After all the horse does not fly ...But doesn't this support, which can be provided by the horse's legs alone, fluctuate...? As for instance in a given gait...? And just as in locomotion the horses' legs support its body for always only split seconds anyway...