In a Sargent Painting, a Vicomtesse Lives On

Laurent de Saint Périer had something he wanted to show his parents. On a recent Tuesday morning, he left his apartment, in the Sixteenth Arrondissement, and walked several blocks to their place, on Avenue Victor Hugo. Saint Périer was wearing dark jeans and a white shirt with raspberry stripes. He had an embroidered scarf that he’d picked up in Ethiopia slung around his neck, and he was discreetly sweating from the effort of having hauled the surprise, which he’d stuffed into a large canvas tote from the children’s-clothing brand Bonton. Once he’d greeted Papa (more formally known as Amaury-Urbain Florian Marie de Poilloüe de Saint Périer de Kergorlay) and Maman (Hélène-Henriette Charlette de Bourbon, before her marriage), he produced an ancient-looking wooden box, which he set on a sideb