litotes vs tropology

litotes

noun
  • An ironic figure of speech whereby something is stated by denying its opposite, particularly the negation of a negative quality to say something positive. 

tropology

noun
  • The use of a trope (metaphor or figure of speech). 

  • The interpretation of scripture or other work in order to educe moral or figurative meaning; a treatise of such interpretation. 

  • A recurring motif or metaphor, a trope; an interplay of tropes. 

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