ceremonial vs plainness

ceremonial

adj
  • Of, relating to, or used in a ceremony. 

noun
  • A ceremony, or series of ceremonies, prescribed by ritual. 

plainness

noun
  • The product or result of being plain 

  • The condition of being plain (in all senses) 

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