Historians recently unveiled a rare 13th-century document depicting the tales of King Arthur and Merlin - and its survival is considered a miracle. The manuscript was discovered in an unlikely place in a Cambridge library - tucked in as the binding for an old book. Thanks to modern technology, experts were able to scan and create a virtual image of the manuscript without risking any damage to it. Each copy of the manuscript was unique, and the Cambridge copy was written between 1275 and 1315.