constancy vs trueness

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. 

trueness

noun
  • Loyalty; faithfulness; constancy. 

  • The characteristic of being true. 

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