enthusiasm vs melancholia

enthusiasm

noun
  • Intensity of feeling; excited interest or eagerness. 

  • Something in which one is keenly interested. 

melancholia

noun
  • Deep sadness or gloom; melancholy 

  • depression, characterised by irrational fears, guilt and apathy 

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