discover vs pick up on

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. 

pick up on

verb
  • To notice, observe, learn, or understand, especially something otherwise overlooked. 

  • To adopt a practice in which others already engage. 

  • To continue or build upon (for example, a task, analysis, or narrative), beginning from a point at which someone has previously stopped. 

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