culmination vs introduction

culmination

noun
  • The attainment of the highest point of altitude reached by a heavenly body; passage across the meridian; transit. 

  • Endpoint (usually good) arrived at after some series of actions or events, or some period , usually after the series or period has ended. The sum of something. 

  • A ceremony marking the completion of studies at an elementary school, middle school or junior high school, the term "graduation" being reserved for high school. 

  • Attainment or arrival at the highest pitch of glory, power, etc. 

introduction

noun
  • A written or oral explanation of what constitutes the basis of an issue. 

  • The act or process of introducing. 

  • A means, such as a personal letter, of presenting one person to another. 

  • An initial section of a book or article, which introduces the subject material. 

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