let in vs ward off

let in

verb
  • To let someone or something come in; to admit someone or something in. 

  • To associate with. 

  • To divulge one's inner thoughts to (someone), making oneself emotionally vulnerable to them; to open up to (someone). 

ward off

verb
  • To parry, or turn aside. 

  • To avert or prevent. 

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