In defending the immaterialism for which he is most famous, George Berkeley, one of the most influential modern philosophers, redirected modern thinking about the nature of objectivity and the mind's capacity to come to terms with it. Along the way, he made striking and influential proposals concerning the psychology of the senses, workings of language, aims of science, and scope of mathematics. A team of distinguished contributors not only examines Berkeley's achievements in this Companion, but also his neglected contributions to moral and political philosophy, writings on economics and development, and defense of religious commitment and religious life.