obedience vs piety

obedience

noun
  • The quality of being obedient. 

  • The collective body of persons subject to any particular authority. 

  • A written instruction from the superior of an order to those under him. 

  • Any official position under an abbot's jurisdiction. 

piety

noun
  • Reverence and devotion to God. 

  • A devout act or thought. 

  • A belief that is accepted unthinkingly and with undue reverence. 

  • Similar reverence to one's parents and family or to one's country. 

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