Thespian vs forerunner

Thespian

noun
  • A person from the ancient Greek city of Thespiae. 

forerunner

noun
  • 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. 

  • A precursor or harbinger, a warning ahead. 

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