be a warning of vs prefigure

be a warning of

prefigure

verb
  • To show or suggest ahead of time; to represent beforehand (often used in a Biblical context). 

  • To predict or foresee. 

noun
  • That which prefigures or appears to predict; a harbinger. 

How often have the words be a warning of and prefigure occurred in a corpus of books? (source: Google Ngram Viewer )