De Agricultura

And for all his restiveness and his continued disregard of the rein, there are whips and spurs prepared, and all other instruments of punishment which have been invented by horse-breakers. And it is not wonderful: for when the horseman mounts, the art of horsemanship mounts too; so that there then being two parties borne by the horse, and skilful in horsemanship, they will very naturally get the better of one animal who is subjected to them, and who is incapable of acquiring skill.