courage vs mettle

courage

noun
  • The quality of being confident, not afraid or easily intimidated, but without being incautious or inconsiderate. 

  • The ability to overcome one's fear, do or live things which one finds frightening. 

  • The ability to maintain one's will or intent despite either the experience of fear, frailty, or frustration; or the occurrence of adversity, difficulty, defeat or reversal. Moral fortitude. 

mettle

noun
  • A quality of endurance and courage. 

  • Good temperament and character. 

adj
  • Spirited, vigorous, stout-hearted. 

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