cold feet vs optimism

cold feet

noun
  • Used other than figuratively or idiomatically: see cold, feet. 

  • A feeling of nervousness or anxiousness causing one to reconsider a decision about an upcoming event. 

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 

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