appetite vs ardor

appetite

noun
  • Any strong desire; an eagerness or longing. 

  • Desire to eat food or consume drink. 

  • The desire for some personal gratification, either of the body or of the mind. 

ardor

noun
  • Great warmth of feeling; fervor; passion. 

  • Intense heat. 

  • Spirit; enthusiasm; passion. 

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