firmness of purpose vs persistence

firmness of purpose

persistence

noun
  • Continuation of the previous day's weather (particularly temperature and precipitation statistics). 

  • The number of times an operation can be iteratively applied to a number before it reaches a permanently constant state. 

  • The property of being persistent. 

  • Of data, the property of continuing to exist after the termination of the program. 

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