childhood vs mettle

childhood

noun
  • The state of being a child. 

  • The time during which one is a child, from between infancy and puberty. 

  • The early stages of development of something. 

mettle

noun
  • Good temperament and character. 

  • A quality of endurance and courage. 

adj
  • Spirited, vigorous, stout-hearted. 

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