perspicacity vs perspicuousness

perspicacity

noun
  • Acute discernment or understanding; insight. 

  • The human faculty or power to mentally grasp or understand clearly. 

perspicuousness

noun
  • The state or characteristic of being perspicuous; perspicuity. 

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