empyrean vs eternity

empyrean

noun
  • The region of pure light and fire; the highest heaven, where the pure element of fire was supposed by the ancients to exist: the same as the ether, the ninth heaven according to ancient astronomy, and Dante's poem. 

adj
  • Of the sky or the heavens; celestially refined. 

eternity

noun
  • Existence without end, infinite time. 

  • A period of time which extends infinitely far into the future. 

  • The remainder of time that elapses after death. 

  • Existence outside of time. 

  • A comparatively long time. 

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