forerunner vs herald

forerunner

noun
  • A precursor or harbinger, a warning ahead. 

  • By extension, a non-competitor who leads out the competitors on to the circuit, or who runs/rides the course prior to competitor trials, usually testing or checking the way. 

  • A postage stamp used in the time before a region or area issues stamps of its own. 

  • A runner at the front or ahead. 

  • A forebear, an ancestor, a predecessor. 

herald

noun
  • A harbinger, giving signs of things to come. 

  • A handbill consisting of an advertisement. 

  • An official whose speciality is heraldry, especially one between the ranks of pursuivant and king-of-arms. 

  • A messenger, especially one bringing important news. 

  • A moth of the species Scoliopteryx libatrix. 

verb
  • To proclaim or announce an event. 

  • To greet something with excitement; to hail. 

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