Marek worked in the reading room of old newspapers, where the days smelled of dust and the nights of quiet scratching of paper. He busied himself correcting maps on which cities moved in the margins as if they had legs of their own. One evening, underneath the lining, he found an index card from a section that wasn't there. The grey cardboard was stamped: 'Register of Non-Existent Things', and next to it was a date from a century ago. When he turned the card over, a transparent envelope fell from it, like a raindrop that no one would notice. In the envelope lay an invitation, written out pale but sure, and signed with a round sign resembling a keyhole. "Come at midnight to the Blank Page Offices, gate C", proclaimed the text, "bring something that never existed". Marek left the library late, with a pencil in his pocket and a strange weight in his throat. The courtyard of the Oficyna was narrow, damp and quiet, and the yellow windows fluttered like dormant butterflies. A cat with eyes like a button perched on a wall, moved its whiskers and disappeared between the plants. Behind gate C stretched a corridor whose doors bore brass plaques: "Murmur", "Delight", "Until tomorrow". At the end stood a desk, at it a woman in a jacket with pockets full of pencils and a warm shadow on her face. "Ms Lucia, I'm deputising for the Warden of Imagination today," she said briefly, and checked the card Mark was clutching in his hand. "The registry only accepts into its care those who remember their first non-existent thing." "Do you remember?" she asked, handing him the pen, which trembled slightly like a leaf on water. Mark remembered something, though he had pretended for years that he did not; a small pane of glass in which the reflections came from tomorrow morning. He signed the agreement with his oldest memory, and the ink shimmered with the colour of trampled puddles after a storm. "Before joining the magazine, you must be able to name what the world is missing," said Ms Lucia. The air dimmed, as if someone had turned down the colour, and the corridor began to lengthen step by step. The storeroom had shelves up to the ceiling, and on each rested objects that knew only someone else's longing. "Spare tree shadows," Lucia whispered, "dictionaries of comet whistles, screws for clouds, clocks that count laughter instead of minutes." Marek stopped at a frosted glass casket where a patch of light lay, wrapped in tissue paper like candy. "It's not yours," she warned softly, "yours waits further away, behind the mirrored door, in the Special Vault." The deeper they went, the quieter the world rumbled, until Marek heard a short, firm knock in his thoughts. Behind the mirror door, smooth as the surface of a pond, a locker marked with his name and a child's whistle awaited. Burned on the brass signboard was: "The mirror that remembers the future", and underneath, dates that were not yet there. "Open!" - soundlessly rang out, just at the moment he thought he could get back in before it was too late. He reached out, touched the cool doorknob, and on the other side someone quietly repeated his next thought. The handle vibrated, the mirror lit up with a silver flicker, and something began to move to that side.