 Mack develops the thesis that this was the earliest writing about Jesus, developed over decades by a community which he describes with unwavering confidence.Following John S. Kloppenborg, he believes that there are three major layers to it, each of which coincides with a stage in this community's life.The layers are significantly structured - the earliest material is spaced out and bracketed by later material, the later material showing awareness of the earlier sayings, but not vice versa.