Sylvia tends to be a bit wordy in general but The Balanced Horse is pretty pithy, with pictures to illustrate key points and it is a compact book. The book is not a training manual, instead it runs through the various aids for different effects and the inter-play between the seat/position and the aids for each desired effect. There are 13 pretty succinct chapters covering everything from balance, weight aids of the seat, rein aids, and much, much more.
A lot of the concepts are very similar to those described in When 2 Spines Align, Centered Riding, or quite frankly any classical text on dressage. The difference is that the descriptions really explain how small differences in body position or placement of the legs make huge changes in the outcome of the aids. For instance, did you know that placing the legs slightly behind the girth while keep the body at vertical has a collecting effect because it slightly tilts the rider's pelvis? Or that to lengthen the stride the legs stay at the girth and the shoulders tip very slightly behind the vertical for a slight driving aid? So if the rider is trying to lengthen the stride but has the legs slightly back things don't work quite right. Hmmmm...sounds vaguely familiar.
There were several revelatory moments just like this about some key things I have struggled with recently. Nothing has been terrible, the work has been coming along, but some things have not been quite right. Now I know why. Projecting from waist to hands and stretching down the weight has almost become habit in the past week and has made a huge difference to the quality of Jet's work and my ability to use much more refined aids. Now it will be a matter of going through all the other tweaks and making the small changes that make a huge difference.