soul-searching vs thoughtful

soul-searching

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

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

thoughtful

adj
  • Demonstrating thought or careful consideration. 

  • Demonstrating kindness or consideration for others. 

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