discern vs espy

discern

verb
  • To detect with the senses, especially with the eyes. 

  • To distinguish something as being different from something else; to differentiate. 

  • To perceive, recognize, or comprehend with the mind; to descry. 

  • To perceive differences. 

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. 

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