This posthumous volume brings together an essay by the author together with a selection of previously published articles (most by Rock) on the theory that perception is an indirect process in which visual experience is derived by inference, rather than being directly and independently determined by retinal stimulation. Rock's reasons for holding that perception is indirect were mainly empirical. He paid close attention to a broad range of experimental evidence in evaluating theoretical claims. His approach, in which theory and experiment go hand in hand, is well represented in this book. In the first chapter, Rock lays out the theoretical issues underlying perception. The remaining 22 chapters present detailed evidence in support of the indirect view. They are divided into sections covering indirect perception, organization, shape, motion, illusions, lightness and final considerations. Each section is introduced by the author. Stephen Palmer's introduction to the book places Rock's work within the context of the history of perceptual theory - approaches forumlated by Helmholtz (inferential), by the Gestaltist psychologists (organizational), and by Gibson (ecological).