This book is an attempt to provide an account of the conception of perception by way of a discussion of the conditions which may have to be satisfied for that concept to have an application. There is included, therefore, a discussion not only of perceptual experience but of the part played in perception by such things as conceptual understanding, belief, imagination, attention and activity. Although there is some reference to psychological work in the field of perception the main approach is philosophical in an analytical style. Nevertheless, the book tends to eschew large gestures in the philosophy of mind, favouring an attention to detail in a way which some might describe as phenomenological. The author has written much about perception in the past and the book might be characterized as summing up a lifetime of thinking about the subject.