freedom vs obstacle

freedom

noun
  • The lack of a specific constraint, or of constraints in general; a state of being free, unconstrained. 

  • The right or privilege of unrestricted use or access 

  • Frankness; openness; unreservedness. 

  • The state of being free, of not being imprisoned or enslaved. 

  • Improper familiarity; violation of the rules of decorum. 

obstacle

noun
  • Something that impedes, stands in the way of, or holds up progress, either physically or figuratively 

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