certainty vs firmness

certainty

noun
  • An instance of being certain. 

  • The state of being certain. 

  • A fact or truth unquestionably established. 

firmness

noun
  • strictness; mental strength 

  • security; steadfastness; good grip 

  • physical durability; rigidness (of material) 

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