In this, one of the most original ancient texts on sense perception, Philoponus, the sixth century AD commentator on Aristotle, considers how far perceptual processes are incorporeal. Colour affects us in the same way as light which, passing through a stained glass window, affects the air, but colours only the masonry beyond. Sounds and smells are somewhat more physical, travelling most of the way to us with a moving block of air, but not quite...