This article examines two forms of 19th-century animal magnetism. The fi rst had its roots in early 19th-century Romanticism, the other fl ourished on the fringe of orthodox science and medicine in the last decades of the century. Common to both is a confl ation of scientifi c experimentation, hermetic thought and popular culture. Mesmerism represented a peculiar, excitingly unorthodox face of 19th-century modernity. Now largely discredited and forgotten, it fed on the contemporary enthusiasm for scientifi c discoveries and confi dence in the human ability to do virtually anything. What distinguished mesmerism from other vitalist theories was its claim to shift the boundary between physics and metaphysics.