stoicism vs strength of character

stoicism

noun
  • A school of philosophy popularized during the Roman Empire that emphasized reason as a means of understanding the natural state of things, or logos, and as a means of freeing oneself from emotional distress. 

  • A real or pretended indifference to pleasure or pain; insensibility; impassiveness. 

strength of character

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