marbles vs shrewdness

marbles

noun
  • Sanity. 

  • Bits of rolled-up rubber shed by the tires of race cars that accumulate at the edges of the track, especially at the corners. 

  • Any of several children's games played with small balls (made of marble or more commonly glass). 

shrewdness

noun
  • The quality of being shrewd. 

  • An invented collective name for a group of apes. 

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