Jules Joseph Dejerine was born in 1839 in Geneva, Switzerland [1–5]. Although his parents, who were originally from France, had only modest means, they encouraged their son to pursue his studies. In 1871, he went to Paris in a third-class train compartment intending to study medicine. He carried with him a brief introduction to Vulpian [1]. Edmé Félix Alfred Vulpian was one of the most influential French physicians at that time. Vulpian soon became a full professor of medicine; he was elected to the Académie Nationale de Médecine and the Académie des Sciences and later became dean of the Paris Faculty of Medicine [6]. Dejerine became a pupil of Vulpian’s at the Hôpital de la Pitié-Salpêtrière. The influence of and the relationship with Vulpian were the strongest and most enduring during his entire career. Dejerine also attended the lectures of Brown-Sequard and later became one of his friends.