optimism vs skepticism

optimism

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

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

  • the belief that good will eventually triumph over evil 

skepticism

noun
  • Doubt or disbelief of religious doctrines 

  • The practice or philosophy of being a skeptic. 

  • The doctrine that absolute knowledge is not possible 

  • A studied attitude of questioning and doubt 

  • A methodology that starts from a neutral standpoint and aims to acquire certainty though scientific or logical observation. 

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