Vision is a classic, a perennial and intuitive, metaphor for knowledge. Shadows play a subtle and important role in good vision. Because of their subtlety shadows are prone to misinterpretation, and, I shall argue, they have in fact been classically misinterpreted. Because of their important role in good vision, this misinterpretation of shadows has led, I shall try to show, to a disregard and denial of the shadow-laden norms of good vision and sound perceptual judgment. And because vision is understood to be a deep metaphor for knowledge, this disregard of the positive role of shadows in vision has in turn naturally led to an idea of shadow-free intellectual knowledge which has itslocus classicus in the work of Plato, particularly in his well-known discussions of the Divided Line and the Allegory of the Cave in Books VI and VII of the Republic. If we retain, as i do, the faith of philosophers such as Plato, Plotinus, Descartes, and Husserl that vision is a deep metaphor for knowledge, then any such demonstration that a given analysis of knowledge, espicially one employing visual metaphor, parallels a misunderstanding of vision, is sufficient to render that idea of knowledge dubious, particularly in light of further evidence of a crucial role played in intellectual knowledge itself by this misunderstood element of vision.