There was a time when strange lights appeared in the marshlands. Commoners might have known the eerie luminescence as "Will-o'-the-Wisp" or "Hinky Punk," while the learned pondered the mysteries of "Ignis Fatuus." Superstitions aside, what natural phenomenon was at work here, before accounts of false fires in the night largely vanished from history? In this episode of Stuff to Blow Your Mind, Robert and Joe search for answers.