concealment vs manifestation

concealment

noun
  • The practice of keeping secrets. 

  • protection from observation or surveillance. 

  • The condition of being hidden or concealed. 

manifestation

noun
  • A pattern or logo on a sheet of glass, as decoration and/or to prevent people from accidentally walking into it. 

  • The act or process of becoming manifest. 

  • The embodiment of an intangible, or variable thing. 

  • The symptoms or observable conditions which are seen as a result of some disease. 

  • This particular manifestation resembled a young girl crying. 

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