The following paper is composed of sections of three earlier publications, all dealing with the relationship of the anatomy of the nervous system to the higher mental functions. The first section is taken from my paper "The Development of the Brain and the Evolution of Language". It discusses the changes in the course of evolution of the brain that made it possible to develop the understanding of names, an essential feature of human language, which is either not present or exists only in rudimentary form in other animals. The second section, taken from "The Neural Basis of Language" discusses a presumably later step in the evolution of human language: The ability to repeat, and its anatomical substrate. In both of these papers the importance of anatomical connections between different portions of the brain is stressed. The third section from "Disconnexion Syndromes in Animals and Man" applies these anatomical principles to certain clinical situations. It is shown here that certain syndromes resulting from localized brain damage and widely interpreted as perceptual in nature are in fact the result of destruction of associative connections between different portions of the brain.