cause vs source

cause

noun
  • The source of, or reason for, an event or action; that which produces or effects a result. 

  • Sufficient reason for a state, as of emotion. 

  • A goal, aim or principle, especially one which transcends purely selfish ends. 

  • A suit or action in court; any legal process by which a party endeavors to obtain his claim, or what he regards as his right; case; ground of action. 

verb
  • To actively produce as a result, by means of force or authority. 

  • To set off an event or action. 

source

noun
  • The person, place, or thing from which something (information, goods, etc.) comes or is acquired. 

  • A reporter's informant. 

  • Source code. 

  • The name of one terminal of a field effect transistor (FET). 

  • Spring; fountainhead; wellhead; any collection of water on or under the surface of the ground in which a stream originates. 

verb
  • To obtain or procure: used especially of a business resource. 

  • To find information about (a quotation)'s source (from which it comes): to find a citation for. 

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