Gordian vs wheels within wheels

Gordian

name
  • Gordianus, name of three Roman emperors. 

adj
  • Of the Gordian knot. 

  • Twisted; convoluted; tied as a knot. 

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

  • Of or pertaining to Gordius, king of Phrygia 

wheels within wheels

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