introspection vs observation

introspection

noun
  • A looking inward; specifically, the act or process of self-examination, or inspection of one's own thoughts and feelings; the cognition which the mind has of its own acts and states 

observation

noun
  • The act of observing, and the fact of being observed (see observance) 

  • The act of noting and recording some event; or the record of such noting. 

  • A remark or comment. 

  • A realization of a random variable. 

  • A judgement based on observing. 

  • Performance of what is prescribed; adherence in practice; observance. 

  • A regime under which a subject is routinely observed. 

  • Philosophically as: the phenomenal presence of human being existence. 

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