harbinger vs signify

harbinger

verb
  • To announce or precede; to be a harbinger of. 

noun
  • A person or thing that foreshadows or foretells the coming of someone or something. 

signify

verb
  • To show one’s intentions with a sign etc.; to indicate, announce. 

  • To mean; to betoken. 

  • To make a difference; to matter (in negative or interrogative expressions). 

  • To create a sign out of something. 

  • To give (something) a meaning or an importance. 

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