audacity vs mettle

audacity

noun
  • Fearlessness, intrepidity or daring, especially with confident disregard for personal safety, conventional thought, or other restrictions. 

  • Insolent boldness, especially when imprudent or unconventional. 

mettle

noun
  • A quality of endurance and courage. 

  • Good temperament and character. 

adj
  • Spirited, vigorous, stout-hearted. 

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