feel out vs spy

feel out

verb
  • To try to ascertain a person's point of view, or the nature of a situation, by cautious and subtle means. 

spy

verb
  • To search narrowly; to scrutinize. 

  • To act as a spy. 

  • To explore; to see; to view; inspect and examine secretly, as a country. 

  • To spot; to catch sight of. 

noun
  • A defensive player assigned to cover an offensive backfield player man-to-man when they are expected to engage in a running play, but the offensive player does not run with the ball immediately. 

  • A person who secretly watches and examines the actions of other individuals or organizations and gathers information on them (usually to gain an advantage). 

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