One night Werner and Jutta tune in to a scratchy broadcast in which a young man is talking in feathery, accented French about light. The brain is locked in total darkness, of course, children, says the voice. It floats in a clear liquid inside the skull, never in the light. And yet the world it constructs in the mind is full of light. It brims with color and movement. So how, children, does the brain, which lives without a spark of light, build for us a world full of light?
