homily vs protreptic

homily

noun

  • A sermon, especially concerning a practical matter. 

  • A platitude. 

  • A moralizing lecture. 

adv

  • In a homey manner. 

protreptic

noun

  • A didactic speech, book, etc. 

adj

  • Serving to instruct; didactic. 

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