confidence vs melancholy

confidence

noun
  • A feeling of certainty; firm trust or belief; faith. 

  • Information held in secret; a piece of information shared but to thence be kept in secret. 

  • Self-assurance. 

melancholy

noun
  • Great sadness or depression, especially of a thoughtful or introspective nature. 

  • Black bile, formerly thought to be one of the four "cardinal humours" of animal bodies. 

adj
  • Affected with great sadness or depression. 

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