grey matter vs percipience

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. 

percipience

noun
  • The state or condition of being highly perceptive, as if in an almost hypnotic or telepathic state. 

  • perception 

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