Fisher was a dedicated teacher and mentor. He spent 5 or more hours each day with his stroke fellows. His method of teaching was Socratic. The fellows would see the stroke cases in depth, then meet with Fisher at dinner, after which, from 6 PM to 11 PM or later virtually daily, they would see the patients together. Fisher continually questioned each fellow about his observations and ideas. He would analyze each neurologic finding—a visual field defect, an arterial retinal embolus, an ataxic arm, or a gait abnormality—often for hours, studying and teaching how the nervous system worked. He was a dedicated reader and could often be found in the Harvard library studying and digesting original English and German reports. He emphasized that “we could not afford to redo the history of neurology every 20 years.” That is, continually rediscovering what had been known but forgotten. He was always available for discussions, characteristically long and detailed, in which he and we would explore a topic. As a very effective role model, his forte was showing how to learn and explore a symptom, sign, phenomenon, or behavior by careful bedside and laboratory analysis and by thorough reading of the literature. His method is captured in a presentation given at his formal retirement titled “Fisher's rules,” which was published in the Archives of Neurology (Figure1A, Figure1B). For the undersigned, he continued to be our mentor and oracle for the duration of his life. He was always available, if only by phone, which became all too frequent in the past few years. He submitted articles for publication until 1996. Until his very last days, he was cognitively intact, and he retained his knack of always knowing what question to ask that would clarify a clinical conundrum.