come by vs obtain

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 

obtain

verb
  • To get hold of; to gain possession of, to procure; to acquire, in any way. 

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