reflection vs soul-searching

reflection

noun
  • Careful thought or consideration. 

  • The act of reflecting or the state of being reflected. 

  • The process or mechanism of determining the capabilities of an object at run-time. 

  • The folding of a part; a fold. 

  • Something, such as an image, that is reflected. 

  • The property of a propagated wave being thrown back from a surface (such as a mirror). 

  • An implied criticism. 

soul-searching

noun
  • Probing introspection; a critical consideration of one's conscience; also, an instance of such consideration. 

adj
  • Involving probing introspection, or a critical consideration of one's conscience, especially motives and values. 

How often have the words reflection and soul-searching occurred in a corpus of books? (source: Google Ngram Viewer )