introspection vs peek

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 

peek

noun
  • A quick glance or look. 

verb
  • To look slyly, or with the eyes half closed, or through a crevice; to peep. 

  • To be only slightly, partially visible, as if peering out from a hiding place. 

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