First published in 2002. This is Volume VII of seventeen in the Philosophy of Mind and Psychology series. The Muirhead Library of Philosophy was designed as a contribution to the History of Modern Philosophy under the heads: first of Different Schools of Thought-Sensationalist, Realist, Idealist, Intuitivist; secondly of different Subjects-Psychology, Ethics, Aesthetics, Political Philosophy, Theology. Written in 1971, the central topic of this book is imaging, more specifically visual imaging and includes the embracing topic of the general question of the nature of mind-or, now that we have taken the linguistic turn, of the content and reference of mental-concept terms.