pessimism vs sadness

pessimism

noun
  • A general belief that bad things will happen. 

  • The condition of being pessimal. 

  • The doctrine that this world is the worst of all possible worlds. 

sadness

noun
  • An event in one's life that causes sadness. 

  • The state or emotion of being sad. 

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