One of the dominant ways of understanding how Biblical narrative emerged was and is the documentary hypothesis which posits four separate and independent story lines fused together by a series of editors who kept what fit their compositional agenda and discarded material which didn't. The alienness of this hypothesis which assumes an editorial process harsher and more invasive than any of the 20th century, to the textual traditions of the ancient near east and the respect they accorded the written word, led me to search for a theory of composition more organic to the time and place in which the Bible was written.
The answer I found based on many predecessors was a version of the supplementary hypothesis. At its most basic level this theory suggests that the way in which Biblical narrative evolved was one of successive additions upon one original and complete text in order to make the text relevant to a new audience of readers - an organic procedure in a culture where the written word was respected, and revelation revered. Each stage of composition was a complete and cohesive work. The first stage, the original source, tells us of Abraham's sin and Isaac's murder. It is coherent and complete and altogether a work of literary genius, it is E: The first book of God.
It was however, only the first stage - The first book of God was followed by, J: The book of Mercy, who resurrected Isaac and composed the first historiographical work of the Bible, then P: The book of Order, who added the bulk of the laws found in the Pentateuch to J's historiographical work and so on and so forth. Each successive supplementation respected the received text and only added to it, the only erasures were accidental.