optimism vs sorrow

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 

sorrow

verb
  • To feel grief over; to mourn, regret. 

  • To feel or express grief. 

noun
  • (usually in plural) An instance or cause of unhappiness. 

  • unhappiness, woe 

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