Objects out of sight didn’t “vanish” entirely, if they influenced the ambient light, but Paul knew that the calculations would rarely be pursued beyond the crudest first-order approximations: Bosch’s Garden of Earthly Delights reduced to an average reflectance value, a single gray rectangle – because once his back was turned, any more detail would have been wasted. Everything in the room was as finely resolved, at any given moment, as it needed to be to fool him – no more, no less.
