" The space is appropriately shoe-boxy and all the shelves are there. I've set them up with a coordinate system, so my program can find aisle 3, shelf 13 all by itself. Simulated light from the simulated windows casts sharp-edged shadows through the simulated store. If this sounds impressive to you, you're over thirty. "

― Robin Sloan , Mr. Penumbra's 24-Hour Bookstore (Mr. Penumbra's 24-Hour Bookstore, #1)