The Cellini saltcellar recently stolen from Austria’s Kunsthistorisches Museum is said to be worth $58 million. How come so much? “The figure they cited is stunning, and no wonder: It comes out of an empyrean that few objects ever visit. Art, like any other commodity, receives its worth partly from the quality of the artifact and partly from its scarcity. But the Cellini is unique—and not just in the sense in which all artworks are unique: Nothing even remotely like it exists. Lose a Warhol, and you can always get another one. Rembrandts are hard to find, but not impossible. But there’s only one Cellini table piece.”