ignite vs instigate

ignite

verb
  • to spark off (something), to trigger 

  • to commence burning. 

  • to set fire to (something), to light (something) 

  • To subject to the action of intense heat; to heat strongly; often said of incombustible or infusible substances. 

instigate

verb
  • to goad or urge (a person) forward, especially to wicked actions; to provoke 

  • to incite; to bring about by urging or encouraging 

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