emancipation vs helotism

emancipation

noun
  • The act of setting free from the power of another, as from slavery, subjection, dependence, or controlling influence. 

  • The state of being thus set free; liberation (used, for example, of slaves from bondage, of a person from prejudices, of the mind from superstition, of a nation from tyranny or subjugation). 

helotism

noun
  • A form of mutualism in which one species is forced to perform tasks for another, for their mutual benefit 

  • The permanent oppression of a nominally free group of people 

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