“Young Woman Seated at a Virginal” is the only mature work by Vermeer to be in private hands; it belongs to Thomas Kaplan, an American billionaire businessman, and his wife, Daphne Recanati Kaplan, who also own the largest private collection of works by Rembrandt. Unlike Frick, Kaplan and his wife do not live with their art; they have gathered their paintings and drawings as the Leiden Collection, which operates as an Old Master lending library. English.