This paper is on matter and on art. Based on the assumption that the everyday attitude toward the world is a kind of materialistic realism and that philosophers, from the beginning of philosophy on, have objected to the plausibility of epistemological reliance on matter, I make attempts to investigate what matter is. I suggest doing this in reference to art. In particular I discuss works of art representing kinds of matter so extraordinary that their material character even could be doubted: light and sound. An installation by James Turrell and a piece of music composed by Morton Feldman, Rothko Chapel, function as paradigms to demonstrate the material character of light and sound and also the affinity of matter to space. Having qualities, matter proves to be different from space; being amorphous, however, matter as such has no distinct appearance, but, like space, enables appearance.