Oh, the Birkin bag lore. An indispensable piece of fashion history, its origin story begins midair. The year was 1981, the airline Air France, and the protagonist Jane Birkin. Upgraded to first class, the British actress and singer found herself seated next to Jean-Louis Dumas, the artistic director of Hermès. As she stashed her overfilled wicker basket in the overhead compartment, its contents—diapers for her daughter Charlotte, cigarettes, business cards—fell into Dumas’s lap. It was a familiar struggle for Birkin, who had difficulty finding a stylish bag big enough to hold her essentials. Inspired by her dilemma, and her elegance, Dumas took note. In 1985, Hermès unveiled its solution: a black leather bag modeled on a previous design meant to hold equestrian gear. Named for Jane Birkin, it became a sensation, a coveted item that women fight to buy. Now that first prototype, stamped with Birkin’s initials and complete with a shoulder strap and her own nail clipper hanging inside, is up for sale. Let the bidding begin! —Jeanne Malle