causation vs purpose

causation

noun
  • The act or agency by which an effect is produced. 

  • The act of causing. 

  • Cause and effect, considered as a system. 

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 causation and purpose occurred in a corpus of books? (source: Google Ngram Viewer )