William Cavendish, first Duke of Newcastle's passions included women, music, writing, theatre and, perhaps above all, the finest horses. He was a widely acknowledged expert in the art of the riding horse, and his works laid the foundation for classical dressage. Mastery in horsemanship was the mark of a graceful and accomplished gentleman in the European nobility of the seventeenth century. In the first comprehensive study of Newcastle's two horsemanship...