epigraph vs proverb

epigraph

verb
  • To provide (a literary work) with an epigraph. 

noun
  • A literary quotation placed at the beginning of a book or other text. 

  • An inscription, especially on a building. 

  • The set of all points lying on or above the function's graph. 

proverb

verb
  • To write or utter proverbs. 

  • To name in, or as, a proverb. 

  • To provide with a proverb. 

noun
  • A striking or paradoxical assertion; an obscure saying; an enigma; a parable. 

  • A drama exemplifying a proverb. 

  • A phrase expressing a basic truth which may be applied to common situations. 

  • A familiar illustration; a subject of contemptuous reference. 

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