In 1957, Italian historian, Carlo Pedretti, rediscovered Leonardo da Vinci’s notebook.  The notebook included the notes and sketches for da Vinci’s anatomical research and many mechanical designs, including the mechanical knight. The image is one of the pages from da Vinci’s notebook.  The notes pictured are from his anatomical study of the human arm.  Image: Public Domain, https://commons.wikimedia.org/w/index.php?curid=59576