espy vs lay eyes on

espy

verb
  • To find out or observe (someone or something, especially if not easy to see) by spying or looking; to catch sight of; to see; to spot. 

  • To see (someone or something) without foreplanning or unexpectedly. 

lay eyes on

verb
  • To see; look at; glimpse. 

How often have the words espy and lay eyes on occurred in a corpus of books? (source: Google Ngram Viewer )