Is there such a thing as a classic?

After Taylor Swift, the “Mona Lisa” is probably the most recognisable female face in the world. Every day around 20,000 people gape at Leonardo da Vinci’s painting in the Louvre. Yet it became famous not because of a beguiling semi-smile, but a thief. Until a worker stole the masterpiece in 1911, it was still mostly unknown; viewers flooded in to see what a French newspaper called “an enormous, horrific, gaping void”.