past master vs prodigy

past master

noun
  • One who has an extremely high level of ability or knowledge within an area of achievement or expertise. 

  • Someone who has previously been a master at a given lodge. 

prodigy

noun
  • An extremely talented person, especially a child. 

  • A wonderful example of something. 

  • An extraordinary occurrence or creature; an anomaly, especially a monster; a freak. 

  • An amazing or marvellous thing; a wonder. 

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