affirmation vs assent

affirmation

noun
  • That which is affirmed; a declaration that something is true. 

  • A form of self-forced meditation or repetition; autosuggestion. 

  • The solemn declaration made by Quakers and others incapable of taking an oath. 

assent

noun
  • agreement; act of agreeing 

verb
  • To agree to a proposal. 

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