A carpenter from northern Italy, Peruggia entered the Louvre on the afternoon of Sunday, August 20, 1911, and concealed himself in a storage closet. He emerged early the following morning dressed in a workman’s white smock and strode into the Salon Carré. He knew the room well; several months earlier, he had helped to construct a special protective case over its most famous attraction, the Mona Lisa. Because it was a Monday, the day the Louvre was closed to the public, he had the salon to himself, and it took only a few seconds to lift Leonardo’s small panel from the wall and carry it to a nearby stairwell. A few moments later, with the painting concealed beneath his smock, Peruggia walked past an unmanned guard post and struck out across the Louvre’s vast center courtyard. And with that the world’s most famous work of art vanished into the Paris morning.

Even more remarkable, twenty-four hours would elapse before anyone noticed the picture was missing. When the alert finally went out, the French police launched a massive if somewhat farcical search. Among their first suspects was an avant-garde painter named Pablo Picasso, who was arrested at his Montmartre apartment despite the fact he had been hundreds of miles from Paris at the time of the actual theft.

Eventually, the gendarmes managed to track down Peruggia but quickly cleared him of any suspicion. Had they bothered to look inside the large trunk in his bedroom, the search for the Mona Lisa would have ended. Instead, the painting remained hidden there for two years, until Peruggia foolishly tried to sell it to a well-known dealer in Florence. Peruggia was arrested but spent just seven months in jail. Years later, he was actually permitted to return to France. Oddly enough, the man who carried out the greatest art crime in history then opened a paint store in the Haute-Savoie and lived there quietly until his death.

Maurice Durand learned several important lessons from the strange case of Peruggia. He learned that stealing great paintings was not as difficult as one might think, that the authorities were largely indifferent to art crime, and that the penalties generally were light. But the story of Peruggia also whet Durand’s appetite. Antique scientific instruments were his birthright—the shop had belonged to his father, and his grandfather before that—but art had always been his great passion. And while it was true there were worse places to spend one’s day than the first arrondissement of Paris, the shop was not a particularly exciting way to earn a living. There were times when Durand felt a bit like the trinkets lining his little display window—polished and reasonably attractive but ultimately good for little more than gathering dust.