keep oneself to oneself vs secrete

keep oneself to oneself

verb
  • To be introverted; to stay away from others. 

secrete

verb
  • To conceal. 

  • To extract a substance from blood, sap, or similar to produce and emit waste for excretion or for the fulfilling of a physiological function. 

  • To exude or yield. 

How often have the words keep oneself to oneself and secrete occurred in a corpus of books? (source: Google Ngram Viewer )