Behind Crandall, the fourth wall was a window of thick plate glass, looking out on the underside of the floating city. The dull blue vista was lit brokenly by flat white rectangles of light staggered along the down-juts of other buildings; the buildings looked like reflections in a pond, upside down. But look closer and you could see men in them: right-side-up men in upside-down buildings. Now and then some glossy, striped, gape-mouthed thing would swim up near the windows, attracted by the lights; jellyfish billowed up, pumping like disembodied heart valves.