grey matter vs intelligence

grey matter

noun
  • Brains; a person's ability to think. 

  • A collection of cell bodies and (usually) dendritic connections, in contrast to white matter. 

  • Literal brains as a general substance. 

intelligence

noun
  • Capacity of mind, especially to understand principles, truths, facts or meanings, acquire knowledge, and apply it to practice; the ability to comprehend and learn. 

  • The quality of making use or having made use of such capacities: depth of understanding, mental quickness. 

  • Information, often secret, about an enemy or about hostile activities. 

  • A political or military department, agency or unit designed to gather information, usually secret, about the enemy or about hostile activities. 

  • An entity that has such capacities. 

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