compulsion vs fixed idea

compulsion

noun
  • An irrational need or irresistible urge to perform some action, often despite negative consequences. 

  • The use of authority, influence, or other power to force (compel) a person or persons to act. 

  • The lawful use of violence (i.e. by the administration). 

fixed idea

noun
  • An idée fixe, an obsession. 

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