Ferdinand II of Spain in a letter of May 23, 1498 to the Marquis of Mantua:
“To answer here what you asked me, that is to say, whether it is necessary that a well-trained horse should obey both the leg and the hand as if, without the repeated action of the hand or the leg, one could not direct all the operations decided by the Cavalier; while you have also seen horses evolve without any help with the firm legs of the rider which seemed immobile, and still others who guided their horse very well without the help of their legs.
Also according to my knowledge and in the logic of our reasoning, I would answer you that given the function of the hand which is to guide the shoulders, that of the legs to guide the hips, the distance which exists from the shoulders to the hips and finally the fact that these are opposing parties, with the art of dressage we will succeed in ensuring that the horse operates with perfect synchronization of the front and rear limbs. But it is also true that, once the horse is trained and understands all the aids, it is necessary to ride without their help, but this is a school for Princes.”
