healing vs placebo

healing

noun
  • The process where the cells in the body regenerate and repair themselves. 

  • An act of healing, as by a faith healer. 

  • The psychological process of dealing with a problem or problems. 

placebo

noun
  • The vespers sung in the office for the dead. 

  • A dummy medicine containing no active ingredients; an inert treatment. 

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