Deep inside Yale's Beinecke Rare Book and Manuscript Library lies a 240 page tome. Recently carbon dated to around 1420, its pages feature looping handwriting and hand drawn images seemingly stolen from a dream. It is called the Voynich manuscript, and it's one of history's biggest unsolved mysteries. The reason why? No one can figure out what it says. Stephen Bax investigates this cryptic work. [Directed by TED-Ed, narrated by Pen-Pen Chen, music by Wonder Boy Audio].