meditation vs soul-searching

meditation

noun
  • A devotional exercise of, or leading to contemplation. 

  • A contemplative discourse, often on a religious or philosophical subject. 

  • Careful and thorough thought. 

  • A musical theme treated in a meditative manner. 

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 meditation and soul-searching occurred in a corpus of books? (source: Google Ngram Viewer )