come upon vs overtake

come upon

verb
  • To befall; to affect; to happen to. 

  • To discover or find, especially by chance or accident. 

overtake

verb
  • To occur unexpectedly; take by surprise; surprise and overcome; carry away 

  • To become greater than something else 

  • To pass a slower moving object or entity (on the side closest to oncoming traffic). 

noun
  • An act of overtaking; an overtaking maneuver. 

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