W.J.T. Mitchell in What is an Image says that It is a commonplace of modern cultural criticism that images have a power in our world undreamt of by the ancient idolaters. And it seems equally evident that the question of the nature of imagery has been second only to the problem of language in the evolution of modern criticism. He adds:

language and imagery are no longer what they promised to be for critics and philosophers of the Enlightenment-perfect, transparent media through which reality may be represented to the understanding. For modern criticism, language and imagery have become enigmas, problems to be explained, prison houses which lock the understanding away from the world. The commonplace of modern studies of images, in fact, is that they must be understood as a kind of language; instead of providing a transparent window on the world, images are now regarded as the sort of sign that presents a deceptive appearance of naturalness and transparence concealing an opaque, distorting, arbitrary mechanism of representation, a process of ideological mystification.

In art history the image is understood in terms of linear perspective in painting. Like Descartes' idealizing of the inner eye of consciousness, perspective, makes the single eye the center of the visible world. Everything converges on to the eye as to the vanishing point of infinity. The visible world is arranged for the spectator as the universe was once thought to be arranged for God. just as Descartes severs vision from the body in order to redefine it as a property of the mind, so the practice of perspective---while ostensibly addressing the spectator's material act of looking at the painting----similarly brackets off the body from the act of perception