anima vs essential nature

anima

noun
  • The inner self (not the external persona) of a person that is in touch with the unconscious as opposed to the persona. 

  • The unconscious feminine aspect of a person. 

  • The soul or animating principle of a living thing, especially as contrasted with the animus. 

essential nature

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