rogation vs sadness

rogation

noun
  • A deeply serious and somber prayer or entreaty. 

  • The demand, by the consuls or tribunes, of a law to be passed by the people; a proposed law or decree. 

sadness

noun
  • The state or emotion of being sad. 

  • An event in one's life that causes sadness. 

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