QUOTES BY PETER SPOHR
On the Rider's Seat

"The normal seat that is vertical to the horse's back supports the hind legs in stepping under as well as in thrusting. Stepping under is favored by leaning forward, placing more weight onto the inseam, thighs, and stirrups, rather than on the seat bones, whereas placing more weight onto the seat bones by a slight backward inclination favors the hind leg's thrusting, extending and staying behind the vertical. Therefore, lightening the horse's flexing side while increasing the weight on the extending side enlarges the stride length. On the other hand, reducing the extension of the hind leg by diminishing and finally completely eliminating the suspension phase by weighting predominantly the hind leg that is stepping under increases the flexion of the haunches considerably (cf. B2: "The diagonal trot without suspension). Conversely, lightening the hind leg that is stepping under and increasing the weight on the thrusting hind leg considerably increases its extension."     (1903; translation: T. Ritter)