appreciate vs discern

appreciate

verb
  • To be fully conscious of; understand; be aware of; detect. 

  • To be grateful or thankful for. 

  • To increase in value. 

  • To view as valuable. 

discern

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

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

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

  • To perceive differences. 

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