enlighten vs mumble

enlighten

verb
  • To make something clear to (someone); to give knowledge or understanding to. 

  • To supply with light. 

mumble

verb
  • To speak unintelligibly or inaudibly; to fail to articulate. 

  • To chew something gently with closed lips. 

noun
  • A quiet or unintelligible vocalization; a low tone of voice. 

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