mettle vs recklessness

mettle

noun
  • A quality of endurance and courage. 

  • Good temperament and character. 

adj
  • Spirited, vigorous, stout-hearted. 

recklessness

noun
  • The state or quality of being reckless or heedless, of taking unnecessary risks. 

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