dirty work vs dualism

dirty work

noun
  • One or more unpleasant tasks, assignments, or employment duties, especially those of a disreputable or illicit nature. 

dualism

noun
  • The belief that the world is ruled by a pair of antagonistic forces, such as good and evil; the belief that man has two basic natures, the physical and the spiritual. 

  • Duality; the condition of being double. 

  • The view that the world consists of, or is explicable in terms of, two fundamental principles, such as mind and matter or good and evil. 

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