See this dialog response. 1. What came before?
Convo:
  Person 1) What is The Language of Music (theory book)?.
  Person 2) The Language of Music (theory book) The Language of Music (2012) is a contemporary music theory book written by Tom Brooks and published by Hal Leonard Publishing..
  Person 1) What is in the book?.
  Person 2) The book explains principles used in modern music starting at a foundational level (Basic Building Blocks of Music) and progressing to topics such as Chord Building, Transposition, Cadences, Modes, and Chord Substitution..
  Person 1) Are there any other interesting aspects about this article?.
  Person 2) The book also demonstrates concepts using well known pop/rock song examples..
  Person 1) Is the book popular?.
  Person 2) It is used as a textbook by college level music theory programs..
  Person 1) What else is notable about the book?.
  Person 2) The book also includes a quick start guide, a chord library appendix, and a DVD with 38 video tutorials by the author..
  Person 1) Did the author write any other books?.
  Person 2) 