light at the end of the tunnel vs optimism

light at the end of the tunnel

noun
  • A better situation after long hardship. 

  • A vision of a bright light, surrounded by darkness, seen by a dying person 

optimism

noun
  • the belief that good will eventually triumph over evil 

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

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

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