optimism vs promise

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 

promise

noun
  • Reason to expect improvement or success; potential. 

  • A transaction between two persons whereby the first person undertakes in the future to render some service or gift to the second person or devotes something valuable now and here to his use. 

  • A placeholder object representing the eventual result of an asynchronous operation. 

  • an oath or affirmation; a vow 

verb
  • To commit to (some action or outcome), or to assure (a person) of such commitment; to make an oath or vow. 

  • To give grounds for expectation, especially of something good. 

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