changed the approach to dog training in recent decades, understanding the role of early trainers and scientists contributes to an appreciation of how particular methods and techniques developed. Before 1900 In around 127-116 B.C. a Roman farmer, Marcus Varro, recorded advice on raising and training puppies for herding livestock. His writings indicate that not only was dog training for specific tasks well established, but that the value of early training was recognized. In 1848 W. N. Hutchinson published his book Dog Breaking: The Most Expeditious, Certain and Easy Method, Whether Great Excellence or Only Mediocrity Be Required, With Odds and Ends for Those Who Love the Dog and the Gun. Primarily concerned with training hunting dogs such as pointers and setters, the book advocates a form of reward-based training, commenting on men who have "a strong arm and a hard heart to punish, but no temper and no head to instruct" and suggesting "Be to his virtues ever kind. Be to his faults a little blind." Stephen Hammond, a writer for Forest and Stream magazine, advocated in his 1882 book Practical Training that hunting dogs be praised and rewarded with meat for doing the correct behavior. War years Konrad Most began training dogs for police work in Germany, and was appointed principal of the State Breeding and Training Establishment for police dogs in Berlin, where he carried out original research into training dogs for a broad range of service tasks. At the outbreak of war in 1914 he was charged with organising and directing the use of dogs to further the war effort. He headed the Experimental Institute for Armed Forces' Dogs during the Second World War, and afterwards ran the German Dog Farm, a centre for the training of working dogs, including assistance dogs for the blind. He played a leading role in the formation of the German Canine Research Society and Society for Animal Psychology. His 1910 publication, Training Dogs: A Manual, emphasized using instinctive behavior such as the prey drive to train desired behaviors, advocated the use of compulsion and inducements, differentiated between primary and secondary reinforcers, and described shaping behaviors, chaining components of an activity, and the importance of timing rewards and punishments. The book demonstrated an understanding of the principles of operant conditioning almost thirty years before they were formally outlined by B.F. Skinner in The Behavior of Organisms. While publishers of the 2001 reprint