If the Midwestern car salesman Harry J. Hahn had still been alive in late January 2010, when the news broke that Sotheby’s auction house in New York had sold the painting for 1.538 million dollars, three times its estimated value, he would have been a very happy man. In 1919, then an American aviator in France during World War I, Hahn had married a local girl called Andrée Lardoux. As a wedding gift, the bride claimed that her aunt, the Comtesse Louise de Montaut, had given the couple an old painting. (Lardoux often changed her story and the “countess” turned out not to be an aristocrat but an impoverished nurse.) In 1917, French art expert George Sortais had certified it to be a work by Leonardo da Vinci, identical to the picture attributed to the artist that hangs in the Louvre known as La Belle Ferronnière or, sometimes, the Portrait of an Unknown Woman.