hortative vs protreptic

hortative

adj
  • Of a mood or class of imperative subjunctive moods of a verb for giving strong encouragement. 

  • Urging, exhorting, or encouraging. 

noun
  • A mood or class of imperative subjunctive moods of a verb for giving strong encouragement. 

protreptic

adj
  • Serving to instruct; didactic. 

noun
  • A didactic speech, book, etc. 

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