Two faces of the teacher: Comparing editions of Charcot's Leçons du mardi.

ABSTRACT Jean-Martin Charcot, renowned teacher and clinical neurologist of the nineteenth century, held a unique set of impromptu “show and tell” case presentations that were transcribed as professor–patient dialogues. These lessons, known as the Leçons du mardi, were hand transcribed by his students and published as a limited-edition lithograph in 1887–1888, but reprinted for wider circulation with modifications in 1892, one year before Charcot died. This study highlights several important differences between the two versions of the work, with interpretative commentary on the importance of studying them side by side to more completely understand Charcot, his career, and the development of early clinical neurology.