dissertate vs sermonize

dissertate

verb
  • To make a dissertation; to discourse. 

  • To write one's dissertation. 

sermonize

verb
  • To say in the manner of a sermon or lecture. 

  • To preach a sermon to (somebody); to give (somebody) instruction or admonishment on the basis of one's morality or opinions. 

  • To speak in the manner of a sermon; to preach; to propagate one's morality or opinions with speech. 

  • To inculcate rigid rules. 

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