bring to heel vs water down

bring to heel

verb
  • To cause to act in a disciplined manner. 

  • To compel someone to obey; to force someone into a submissive condition. 

water down

verb
  • To make less restrictive; to make more lenient. 

  • To simplify or oversimplify; to make easier; to make less difficult. 

  • To make weaker, less effective. 

  • To dilute; to add water to. 

How often have the words bring to heel and water down occurred in a corpus of books? (source: Google Ngram Viewer )