Just one to cap it off. You're now in a top view, looking down onto the light-source-surface. In front of that has been placed a set of boxes in various shapes and sizes, all of which have mirrored surfaces. The point of the positioning of the boxes is to stop light from the light-source-surface shining directly outside of the group. The only way out for the light is by reflection of reflection of reflection... (image has had brightness and contrast boosted to show the effect more clearly)