A sentence written on the underside of a plane — readable only from this exact vantage, by an observer who does not know they are looking up.
Three accounts of the same vanished afternoon. Each is true. The contradictions are part of the geometry.
The witness recalls a circular room with the texture of paper held too long against a flame. There were chairs but no people, and the chairs were still warm. The air smelled of something the witness almost recognised but could not name; later, much later, she would call it Tuesday.
The second witness, sworn in a different language, described a hexagonal corridor lined entirely with doors at uneven heights. The chairs he remembered hung from the ceiling, comfortable in a way that should have been impossible. He left through a door that had not been there moments before, and when he turned back, neither was the corridor.
The third witness laughed when asked. She said the others had been describing a feeling, not a place, and that feelings have walls only when you choose to live inside them. She said the chairs were a metaphor, the door was a metaphor, the witness was a metaphor. Then she paused, and added quietly: but the warmth, the warmth was real.
To read this you have already tilted your head. You did not notice when. Gravity is a habit, not a law; the first time you fell asleep on a moving train you understood this, briefly, before forgetting. The note that hangs above you was written by someone who is, at this moment, also reading it, also upside down, also unsure which of you is the original.
Below this note — which is to say, above — there is nothing. Or rather: there is the same nothing that is below your feet right now, which you have agreed, by long custom, to call a floor.
The corridor begins at the width of an open door, and the air here still smells of the room you left. There is no instruction to walk forward; you are already walking, the way one is already dreaming the moment one notices the dream.
Three paces in, the walls have narrowed by a measurable but unimportant amount. A small brass plaque on the left, illegible from this distance, will only become readable when you have already passed it.
The lights overhead are not lights, you realise, but the absence of ceiling above each one. The sky beyond is the colour of an envelope you have been meaning to open since childhood.
You have begun to stoop without remembering when. The text on these walls is your handwriting, though you do not recall writing here, and the dates do not yet exist.
The corridor is now narrow enough that you can touch both walls at once, and you do, because it is a kind of comfort. The walls are warm. They have been waiting for you.
At the far end, a door, or the suggestion of a door — a darker rectangle in the dark. You will arrive without choosing to.
The end is the beginning seen from the opposite side. You arrived at the door you set out from, and the door has been waiting all along.