enthusiasm vs lassitude

enthusiasm

noun
  • Intensity of feeling; excited interest or eagerness. 

  • Something in which one is keenly interested. 

lassitude

noun
  • Lethargy or lack of energy; fatigue. 

  • Listlessness or languor. 

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