The possibility of human mechanical flight held particular fascination for Leonardo da Vinci.  He produced more than 35,000 words and 500 sketches dealing with flying machines, the nature of air, and bird flight.  He produced one notebook, or codex, almost entirely on flight in 1505-1506, known as the Codex on Bird Flights.  In this codex, Leonardo outlined a number of observations and beginning concepts that would find a place in the development of a successful airplane in the early twentieth century.  This extraordinary document, exhibited outside of Italy only a few times, is on display at the Smithsonian’s National Air and Space Museum in The Wright Brothers & The Invention of the Aerial Age gallery from September 13-October 22, 2013.  The story of the journey of the Codex on the Flight of Birds from the hand of Leonardo to the National Air and Space Museum exhibit is as fascinating as the document itself. The death of Leonardo da Vinci in 1519 was the beginning of an odyssey that would bring the Codex on the Flight of Birds to the Biblioteca Reale in Turin, Italy, more than four centuries later.  Along the way it would be in the possession of at least ten individuals and pass through as many as nine locations, including the remote Siberian border. Leonardo bequeathed all his manuscripts to his pupil and trusted friend, Francesco Melzi.  Melzi transferred the manuscripts he inherited from Leonardo to his house at Vaprio d’Adda, outside Milan, where he gave them good care until his death in 1570.  Melzi’s heirs were not as conscientious or scrupulous as he, and after a few short years allowed the collection of da Vinci treasures to be split up.  Given away, stolen, and sold, as complete codices or singles pages, Leonardo’s manuscripts passed from person to person and place to place for decades. In 1637, the Codex on the Flight of Birds surfaced at the Biblioteca Ambrosiana in Milan.  The journey to the Biblioteca Ambrosiana can be traced in the memoires of Giovanni Ambrogio Mazenta.  He recalled that he had seen thirteen notebooks by Leonardo about 17 years after Francesco Melzi died in the possession of Lelio Gavardi, a tutor to the Melzi family, who Mazenta claimed had stolen them.  Mazenta convinced Gavardi to return the notebooks to the Melzi family.  Impressed by Mazenta’s honesty, Orazio Melzi, son of Francesco, made a gift of the thirteen notebooks to Mazenta.  In fact, he offered to let him have anything else he wanted from the remaining materials bequeathed to his father by Leonardo.  Once word spread of Orazio Melzi’s seeming lack of interest in the Leonardo treasure trove, collectors and dealers descended, leading to the dispersal of the surviving evidence of the wide-ranging work of the genius from Vinci. Among those who ended up with several of the Leonardo codices was Pompeo Leoni, who came into possession of them after the death of Mazenta’s brother.  He disassembled them to organize the pages by subject and collated them into what became the Codex Atlanticus.  In 1610, Polidoro Calchi, Leoni’s son-in-law, sold the manuscripts to Galeazzo Arconati, who later donated the material to the Biblioteca Ambrosiana in 1637.  Arconati’s gift records the first specific mention of the Codex on the Flight of Birds since it passed from Leonardo to Melzi in 1519.  From this point forward, movements of the Codex on the Flight of Birds specifically are known. In November of 1796, Napoleon Bonaparte had all the Leonardo da Vinci manuscripts in the Biblioteca Ambrosiana transferred to Paris as payment of war tributes.  These manuscripts included the Codex Atlanticus, of which at that time the Codex on the Flight of Birds was a part.  In 1815, the Codex Atlanticus was returned to the Biblioteca Ambrosiana through intervention by the Vatican.  A part of it, however, known as Manuscript B, which included the Codex on the Flight of Birds, remained in France. Between 1841 and 1844, a mathematician and book lover named Guglielmo Libri spent time in Paris studying the manuscripts still there.  He removed a number of pages, including the entire Codex on the Flight of Birds, with the intention of selling them.  Libri took apart the Codex on the Flight of Birds.  Five pages (1, 2, 10, 17, and 18) were sold in London between 1859 and 1864, ending up in the hands of a painter and art collector, Charles Fairfax Murray.  The other thirteen pages were sold to Giacomo Manzoni, and upon his death in 1889, passed to his heirs.  In 1892, a Russian named Theodore Sabachnikoff, who was an avid student of the Italian Renaissance, bought the 13 pages of the Codex on the Flight of Birds the Manzoni family inherited.  When Charles Fairfax Murray learned of this, he sold to Sabachnikoff one of the five pages he owned, page 18, not realizing the other four were from the same notebook.  Sabachnikoff’s goal was to publish the Codex on the Flight of Birds, and having done so then generously gifted it to Queen Margherita of Italy, who deposited it in the Biblioteca Reale in Turin in December 1893.  Ten years later, page 17 made its way to Turin.  The last three pages (1, 2, and 10) were sold to a collector from Geneva, Enrico Fatio, who a few years later gave them to King Victor Emmanuel III of Italy, who reunited them with the others.  Finally, after four centuries of extraordinary twists and turns, Leonardo da Vinci’s complete Codex on the Flight of Birds came to rest in the Biblioteca Reale in Turin. The Codex exhibit at the National Air and Space Museum will be a once-in-a-lifetime opportunity to appreciate the genius of da Vinci in the same space as the Wright Flyer, which made the airplane a reality four centuries after the Leonardo produced the Codex on the Flight of Birds. Peter L. Jakab is chief curator at the National Air and Space Museum.