Conspiracy theories and the theft of the Mona Lisa.

A claim of patriotism can justify almost anything.

The news came on a Tuesday night; and, for a moment, the people of Paris forgot their worries about the possibility of another war.

The Mona Lisa had vanished from her place on the wall of the Salon Carré, the Louvre’s gallery of Renaissance treasures, and no one knew what had become of her.

The painting’s disappearance on August 21, 1911, filled the fr…