Gordian vs mystifying

Gordian

adj
  • Twisted; convoluted; tied as a knot. 

  • Of the Gordian knot. 

  • Of or pertaining to Gordium (now Yassihüyük in Turkey), capital of Phrygia. 

  • Of or pertaining to Gordius, king of Phrygia 

name
  • Gordianus, name of three Roman emperors. 

mystifying

adj
  • Very hard to understand; baffling. 

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