For example, Martin Luther's Tischreden have numerous -quite serious- references to dealing with kobolds.[3][4] Eventually, rationalism and the Industrial Revolution threatened to erase most of these minor deities, until the advent of romantic nationalism rehabilitated them and embellished them into objects of literary curiosity in the 19th century. Since the 20th century this literature has been mined for characters for role-playing games, video games, and other fantasy personae, not infrequently invested with invented traits and hierarchies somewhat different from their mythological and folkloric roots.