It would seem that the filmmaker Michael Haneke, who wrote and directed the wrenching and poignantly acted new French movie “Amour,” is swept away by the mystique of a pianist, alone onstage, conveying mastery and utter oneness with music by playing a great piece from memory. The drama of playing from memory is at the crux of a scene involving the elegant French pianist Alexandre Tharaud, who, portraying himself, has a small but crucial role.

The story revolves around an elderly Parisian couple, Georges and Anne, retired music teachers, as they cope with the stroke that has paralyzed Anne’s right side. In one scene Mr. Tharaud, in the role of a former student of Anne’s who has gone on to a significant career, makes an unannounced visit to his old teacher to see how she is faring. He can barely contain his shock at her condition. Anne (Emmanuelle Riva) asks a favor: Would Alexandre play a piece she made him learn when he was 12? It is Beethoven’s Bagatelle in G minor, the second of the Six Bagatelles (Op. 126), Beethoven’s last published piano work.

At first Mr. Tharaud demurs. He has not played the piece for years, he explains, and is not sure he can remember it. Then, saying he will try, he proceeds to play the stormy bagatelle flawlessly, at least as much as we hear before the film cuts to the next scene. I suppose it would have been too pedestrian a touch if, when Alexandre said he was not sure he could remember the bagatelle, Anne had said, “Oh, I have the score, of course, right there on the shelf.”