discover vs light upon

discover

verb
  • To find or learn something for the first time. 

  • To create by moving a piece out of another piece's line of attack. 

  • To question (a person) as part of discovery in a lawsuit. 

light upon

verb
  • To find or think of something unexpectedly. 

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