According to the documentary hypothesis, the first four books of the Pentateuch, or Torah, were created through a combination of three major narrative sources. The three sources are the J or Yahwist source (which starts with the Eden story in Genesis 2–3), the E or Elohist source (which includes the story of the binding of Isaac) and the P or Priestly source (which starts in Genesis 1, then resumes in Genesis 5). J and E were combined first; P was combined with J and E afterward, perhaps by the time of the Book of Deuteronomy. For a summary, see Richard Elliott Friedman, Who Wrote the Bible? (Summit, 1987).