introspection vs thought

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 

thought

noun
  • Representation created in the mind without the use of one's faculties of vision, sound, smell, touch, or taste; an instance of thinking. 

  • A very small amount, distance, etc.; a whit or jot. 

  • A way of thinking (associated with a group, nation or region). 

  • The operation by which mental activity arise or are manipulated; the process of thinking; the agency by which thinking is accomplished. 

  • Anxiety, distress. 

  • The careful consideration of multiple factors; deliberation. 

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