Fingers fumble for that switch, the magical trigger that instantly plunges its operator into a familiar world, where everything is clear. If only he could find it. Inching like worms across the smooth wall, they pounce, latching on now with elated satisfaction. They feel cautiously, doubt and disappointment creeping in. No, this is not it. A frustrated grunt escapes into the gloom. The worms resume their search, now desperate to discover the target. Aha! The fingers move together in a clumsy but joint motion, up, down, up, there! Light floods the world, making everything clear.