1. The OT
Although the Pentateuch reads well as a coherent and continuous document and was certainly in existence as it is by the 4th cent. BCE, closer examination reveals that it contains a number of sources. Some of these are named: e.g. ‘the book of the wars of the Lord’ (Num. 21: 14–15). Other items in the OT seem also to have existed independently, such as the lament of David (2 Sam. 1: 18). But critical scrutiny of the text of the Pentateuch has disclosed clear evidence that several formerly separate sources now form the book we have today. It was noticed, for example, that the creation narrative in Genesis closes at 2: 4a and another parallel narrative, different in style and content, takes over at 2: 4b. Similarly, in Gen. 6: 5–9: 19, the story of the Flood, there are not only differences in style, but also contradictions and inconsistencies—e.g. seven pairs of animals are to be taken into the ark (Gen. 7: 2) but only one pair in Gen. 6: 19.
The widely accepted hypothesis to account for these features in the Pentateuch fastens particularly on the different names used for God—Yahweh and Elohim. The sources have been given the symbols J, E, D, and P. J from Jahveh (the German form for Yahweh) is thought by many scholars to derive from the south of the country in the 9th cent. BCE; J gives the account (Gen. 2: 4b ff.) of the creation of humanity and its early history and then the story of the early years of the elect nation under divine providence; E (from Elohim) from the north in the 8th cent. BCE. The name Yahweh was not known to the patriarchs but was first revealed to Moses (Exod. 3: 14); D = Deuteronomy, associated with King Josiah's discovery of the law book in the Temple (622 BCE) consists of important speeches, e.g. of Moses to the Israelites. But the influence of D continues into the historical narratives in Josh., Judg., 1 & 2 Sam., and 1 & 2 Kgs.; and P (‘Priestly’) also has a creation narrative, Gen. 1–2: 1a and is dated to the Babylonian Exile or just after with a strong interest in the ritual of the sanctuary and the emphasis on offerings being made by priests of the tribe of Levi. This four-document hypothesis is attributed to the German scholars Graf and Wellhausen, and it remains a springboard for all OT research. Nevertheless much of the hypothesis has been disputed; perhaps the most vulnerable part is the identification of a source E. It is held by some that the different names for God are not sufficient ground for positing different literary sources.
Without denying the legitimacy of the division of the Pentateuch into four sources, there are nevertheless those who much prefer to read and value it as a single plea of literature, as it always has been in synagogue and church, with a meaning and a message in its final form.
There are also conservative scholars who reject the documentary theory of sources altogether and point to a lack of consensus about the historical contexts of the four sources. Therefore, they suggest, it is wiser to assume that the Pentateuch was first compiled in the form of short narratives which were later coordinated into a continuous literary piece, possibly in the course of cultic festivals. Elsewhere in the OT it is widely agreed that Isa. 1–39 is an editorial compilation of sources, and certainly distinct from Isa. 40–66.
2. The NT
It is generally accepted that the close verbal relationships between the synoptic gospels demand a hypothesis about the use of sources. Luke (1: 1) actually explains that the author knew of several predecessors. Although there is no universally agreed solution to the synoptic problem, it is usual to hold that Mark was the first gospel to be written, and that Matthew and Luke embodied Mark in their longer works. The remaining material common to Matthew and Luke is explained either by their both having access to the same source (‘Q’) of tradition, or (a minority view) that Luke knew Matthew as well as Mark.
There is a minority view that the gospel of John is a compilation of pre-existing sources, e.g. of the Signs or the Discourses, arranged under the heading of the Feasts. A pattern on the whole work has been imposed by an editor. But an objection to this view is that the work as a whole has a consistent and recognizable style. It is, however, probable that the author of John had available written sources of material, such as the accounts of the Feeding of the Multitude, used in John 6: 1–21.