Throughout the nineteenth century, and into the twentieth, advancing knowledge about the brain's functions kept in perpetual motion a pendulum which swung between two polar beliefs. Especially as concerns the "psychic" functions of the cerebrum, upholders of "action propre" asserted that specific functions have specific loci within a major subdivision of the brain while supporters of "action commune," or field theory, maintained that a structure such as the cerebrum exerts a unitary or equipotential action. The effective impetus to a detailed scientific study of the brain as the "organ of mind" came in the nineteenth century, in part through the impact upon scientific thought of the physiologic doctrine of phrenology.' Phrenology's founder, Franz Joseph Gall (1758-1828), and its chief popularizer, G. Spurzheim (17761832) sought to establish empirically the postulates that brain is the organ of mind and that, in producing mental phenomena, brain has a highly specific action propre. In emphasizing the significance of Gall's and Spurzheim's work, however, one must realize that both of their postulates were well established, at least speculatively, before the nineteenth century.