constancy vs frailty

constancy

noun
  • The quality of being constant; steadiness or faithfulness in action, affections, purpose, etc. 

  • An unchanging quality or characteristic of a person or thing. 

frailty

noun
  • The condition quality of being frail, physically, mentally, or morally; weakness of resolution; liability to be deceived. 

  • A fault proceeding from weakness; foible; sin of infirmity. 

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