ennui vs enthusiasm

ennui

noun
  • A gripping listlessness or melancholia caused by boredom; depression. 

verb
  • To make bored or listless; to weary. 

enthusiasm

noun
  • Intensity of feeling; excited interest or eagerness. 

  • Something in which one is keenly interested. 

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