lucidity vs obscurity

lucidity

noun
  • The state of being aware that one is dreaming, i.e. being in a lucid dream. 

  • The property of being lucid, lucidness. 

obscurity

noun
  • The state of being unknown; a thing that is unknown. 

  • The quality of being difficult to understand; a thing that is difficult to understand. 

  • Darkness; the absence of light. 

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