knowable vs lucid

knowable

adj

  • Capable of being known, understood or comprehended. 

lucid

adj

  • clear; easily understood 

  • bright, luminous, translucent or transparent 

  • mentally rational; sane 

noun

  • A lucid dream. 

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