"I do not approve of a seat which is as though the man was sitting on a chair, but rather as though he was standing with his legs apart."
Xenophone, 355 BC, Athenian philosopher and cavalry leader.
A Good Posture
In a chair position, the points of gravity in the human skeleton are not aligned. In a standing position, a straight vertical line can connect the points of gravity. The points of gravity start with the ear, then the point of the shoulder, then the second sacral vertebra, then the hip joint, and finally, the ankle.
What Xenophone implied in his writings was to maintain the straight vertical line while in the saddle. To put the picture together, stand with your side to the mirror, shoulders square, back straight, legs slightly apart. Now bend your knees as they would be if you were in the saddle. Make sure that you keep your back straight and your shoulders square. You will notice the vertical line connecting the points of gravity has not changed. This is the ideal posture that leads to harmony between you and your horse as it places the rider in responsibility of their own weight.
Why That Particular Seat?
Horses are sometimes unpredictable. A good confident seat will provide the rider with security and safety in case of emergencies. A chair position in a saddle can result in an insecure seat and inevitable falls. With your legs forward in the chair position, you are loosing contact between your inner thigh muscles and the horse. These muscles, when assisted with a proper leg position (i.e. maintaining the vertical line of gravity) act as a seat belt - holding you in place - when an emergency occurs.
The Chair Seat
Stirrups are short and the leg is too far forward, which causes uneven weight distribution and a weak seat.
The Correct Seat
The shoulder, hip, and heel can all be connected by one vertical line. This is a truly balanced, secure position
There are several benefits resulting from a good seat. Among them are safety, control, comfort, elegance, confidence, and harmony with your horse.