come by vs earn

come by

verb
  • To obtain; to get, especially by chance or involuntarily. 

  • To come near to; to pass; to visit. 

intj
  • A command to a sheepdog to move clockwise around the sheep 

earn

verb
  • To gain (success, reward, recognition) through applied effort or work. 

  • To cause (someone) to receive payment or reward. 

  • To achieve by being worthy of. 

  • To receive payment for work. 

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