belief vs optimism

belief

noun
  • The quality or state of believing. 

  • Mental acceptance of a claim as true. 

  • Religious faith. 

  • One's religious or moral convictions. 

  • Faith or trust in the reality of something; often based upon one's own reasoning, trust in a claim, desire of actuality, and/or evidence considered. 

  • Something believed. 

optimism

noun
  • a tendency to expect the best, or at least, a favourable outcome 

  • the doctrine that this world is the best of all possible worlds 

  • the belief that good will eventually triumph over evil 

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