intentive vs penetrating

intentive

adj
  • Expressing intent. 

  • Paying attention; attentive, heedful. 

  • Intent (of the mind, thoughts etc.). 

penetrating

adj
  • demonstrating acute or keen understanding 

  • able to pierce or penetrate 

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