buy vs earn

buy

verb
  • To obtain (something) in exchange for money or goods. 

  • To make a purchase or purchases, to treat (for a drink, meal or gift) 

  • To make a bluff, usually a large one. 

  • To bribe. 

  • To be equivalent to in value. 

  • To obtain, especially by some sacrifice. 

  • to accept as true; to believe 

noun
  • Something which is bought; a purchase. 

earn

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

  • To achieve by being worthy of. 

  • To receive payment for work. 

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

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