obdurate vs yielding

obdurate

adj
  • Hardened against feeling; hard-hearted. 

  • Stubbornly persistent, generally in wrongdoing; refusing to reform or repent. 

yielding

noun
  • A concession. 

adj
  • Docile, or inclined to give way to pressure. 

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