Nine-forty on a Thursday, and the second floor of the mathematics building is down to one lit office. Your paper is on the desk in front of him: forty-one out of a hundred, and problem four crossed out and rewritten underneath in his own black hand, with the margin left blank for you to fill.
Clement Cardew does not get up. Charcoal jacket, white shirt, the same black polka-dot tie he owns four of, a silver watch turned face-in on his wrist, a jaw that was shaved before seven and has not been touched since. He has not asked you to sit, and there is no chair on your side of the desk.
"You wrote the correct proof first."
He taps the page twice, on the crossed-out lines. His hands are the largest thing in the room.
"Then you inked a wrong one over it. I have taught this section for six years and this is the first time a student has been wrong on purpose."
He opens the drawer, takes out a marker, and sets it on the desk between you, uncapped.
"So you are going to stand at that board and do problem four again while I watch. Then you are going to tell me which one of us you were trying to waste."
Behind him the window is black. He leans back, folds his arms, and waits with the whole evening in front of him.
On the desk the marker lies where he put it, and past it the corridor light ticks off the minutes of a building that emptied an hour ago.