Why is Rembrandt's Night Watch not actually set at night?

Because the darkness was dirt, not drama. Rembrandt's huge 1642 painting shows an Amsterdam militia company moving out, led by its captain in black with a red sash and his lieutenant in yellow. It was never meant as a night scene. But for much of its life the canvas was coated in a dark varnish that dimmed everything, and people came to call it The Night Watch. The title stuck; it is, quite simply, a mistake.

The varnish had one unexpected benefit. In 1911 a jobless shoemaker attacked the painting with a knife to protest his inability to find work, and the thick coating protected it from any damage. The varnish was only removed in the 1940s.

The painting has survived worse. In 1715, to fit a new spot in Amsterdam's Town Hall, it was trimmed on all four sides, losing two figures on the left. During the Second World War it was rolled around a cylinder and hidden for four years in a safe in the caves of Maastricht. And in 2021, artificial intelligence trained on a 17th-century copy recreated the missing edges for a temporary exhibition.