agitate vs ignite

agitate

verb
  • To disturb or excite; to perturb or stir up (a person). 

  • To cause to move with a violent, irregular action; to shake. 

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. 

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