big picture vs purpose

big picture

noun
  • The totality of a situation. 

  • Used other than figuratively or idiomatically: see big, picture. 

purpose

noun
  • Function, role. 

  • meaning for existing or doing something. 

  • Resolution; determination. 

  • The end for which something is done, is made or exists. 

verb
  • To have or set as one's purpose or aim; resolve to accomplish; intend; plan. 

  • To have (an) intention, purpose, or design; to intend; to mean. 

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