Excerpt from "On the use of mirrors in the game of chess" by Milo Temesvar. (Created by Umberto Eco in The Name of the Rose)
For the second game I moved the mirror. When she arrived, she looked nervously at the mantlepiece and seeing the mirror's absence sighed very gently. I guided her to the chess table, noticing that the collar of her dress was embroidered with white pawns. She took Black this time, as I had expected. I sat opposite her and advanced my Queen's pawn. I could see her both before me and reflected in the mirror. Her hand hovered like an albino hummingbird over her pawns.
She played cautiously as before, and again the careful placement of the mirror was to my advantage. Her tells were shown as clearly as any amateur poker player's, and I discerned her strategies effortlessly. As her attack splintered against my artful pawn formation, I saw her grow agitated, and again her reflection in the mirror took on an opalescent lustre. Abruptly she sacrificed a rook, and in the mirror her reflection turned and snarled soundlessly at me, crimson lips curling away from white teeth, and her eyes as brilliant and green as new-cut emeralds.
Numbed, my hands moved of their own accord and i rejected her sacrifice, counter-offering the lynchpawn of my defense. Her reflection returned to normal, but it was too late; I crumbled and resigned a few moves later.
She sat back and smiled slightly and I caught the briefest possible glimpse of a flash in her hand. Instantly I understood. I was not alone in employing the art of mirrors to chess.