cautionary tale vs parable

cautionary tale

noun
  • A story, originally told in folklore, to warn its audience of a certain danger. 

parable

noun
  • A short narrative illustrating a lesson (usually religious/moral) by comparison or analogy. 

verb
  • To represent by parable. 

How often have the words cautionary tale and parable occurred in a corpus of books? (source: Google Ngram Viewer )