In 1878, Robert Louis Stevenson, author of classics such as Kidnapped and Treasure Island, embarked on a walking tour of the Cévennes, a mountainous region in south-central France. His travelling companion was Modestine, a diminutive donkey with a mind of her own who, over the course of the journey, bore some of his provisions and much of his rancour. Modestine and Stevenson tramped without plan or purpose through scenic villages and fearsome forests-reportedly...