The Priestly (P) Source was written after the destruction of the Jerusalem temple in 587 BC. It was the last of the underlying sources for Genesis, Exodus, Leviticus and Numbers to be written. It was designed to encapsulate as much as it could of the information about the Israelite religion, in particular those pieces of information that were about to lost following the destruction of the Jerusalem temple by Nebuchadnezzar.
There are five elements to the P Source.
- That part of the Akkadian Source material that contained the first creation account (found in Genesis 1), the genealogy of mankind modelled on the Sumerian king lists (found in Genesis 5, 10 and 11), and the first account of Noah and the flood (found in Genesis 6-9).
- That part of the Akkadian Source material that contained the history of Jacob’s family written by Joseph’s grandchildren.
- That part of the Akkadian Source material that contained the Israelite censuses, and some other items that can be found in the book of Numbers, written during the Israelite wilderness wanderings.
- Material derived from the E Source story of the exodus and initial wilderness wanderings.
- The memory of the ordering of the worship and religious practices in the Jerusalem temple before it was destroyed by Nebuchadnezzar.
These things were brought together by the P Source writer in a new account of the history of the Israelite people that was orientated towards a “temple-based” view of the Israelite religion.
Akkadian tablets
The following steps were required before the Akkadian Source material could have survived during the period from Israel’s Egyptian sojourn until the Babylonian exile:
- Joseph to have served in the highest levels of the Egyptian society, so that some of his children could have learnt the difficult Akkadian cuneiform.
- Joseph’s family to be exposed to Egyptian mythology (which is reflected in Genesis 1).
- Joseph’s family to be exposed to old Sumerian mythology, such as the Sumerian king lists and the Atrakhasis myth (which are reflected in parts of Genesis 5 to 11).
- The results of this research and expanded knowledge to have been recorded in Akkadian cuneiform, and for the tablets containing this information to be physically carried by the Israelites when they left Egypt.
- The  tablets to be kept safe in Israel, probably in Shiloh, where the central Tent of Meeting was located, and then for the tablets to be moved to Jerusalem when the Tent of Meeting was established there.
- The Babylonians to take these tablets from Jerusalem to Babylon (before the temple was destroyed).
- The Babylonians to make the tablets available to the Israelite / Jewish scholars in Babylon.
All of this is both feasible and in accordance with the totality of the Biblical evidence.
Akkadian Source material
The P Source writer mostly relied on the Akkadian Source material when he was preparing his material that now finds itself in the book of Genesis.
In Exodus, very little P Source material came from the Akkadian Source, with the exception of some of the rules surrounding the Passover.
(King Josiah was shocked when rules for the celebration of the Passover were discovered that had “never” been followed in Israel. These rules were found when the temple was being renovated (2 Kings 22-23). This was not the “discovery” of Deuteronomy, as many scholars believe; it was the uncovering of Akkadian material, which only very few people could actually read, as can be gleaned from the account of this event in Kings .)
Some sections of Numbers seem to be drawn (at least partially) from Akkadian Source material. These include:
- The first census of the men-at-arms for the proposed invasion of Canaan from the south.
- Rules for the Passover – in Numbers 9 – also found in Exodus.
- Sending out the scouts in the land, and their report on returning.
(In P, Joshua has been exonerated from blame, whereas J does not exonerate him at all. Rather than either J or P reflecting the actual situation from Moses’ perspective, it is likely that Caleb (the only faithful scout in J) was a hothead, and invasion at that time would have come up against fierce resistance from Egyptian proxies in Canaan. On this basis, J is probably right to imply that Joshua did not support the invasion of the land, and both J and P are wrong to have assumed that it was treated as rebellion against Yahweh.)
- The execution of a man who collected wood on a rest day in contradiction to the laws set down by Moses.
- The summary execution of two people while engaged in sexual congress. One was the leader of the Simeonites, the other was a princess from the Midianite royal family. They went into the Tent of Meeting in order to have sex. This execution was done by the hothead Phineas, the grandson of Aaron, and later high priest.
(Phineas also emerges as a hothead in Judges.)
- The second census of the men-at-arms in preparation for the invasion of Canaan from the east, before crossing the Jordan River.
- The rule for inheritance where a father dies without sons (and possibly the later refinement of this rule).
- The promise of the Gadites and the Reubenites to commit to the invasion of Canaan in return for permission to settle on the east side of the Jordan.
P Source interventions
The  P Source writer made changes to the Akkadian Source material when writing his Genesis material, relating to the story of Abraham:
- He attributed to Abraham the promises later made to Jacob.
- He attributed a circumcision covenant to Abraham, which is unlikely to be historical.
- He made Sarah impossibly old when she gave birth to Isaac, thus increasing the “miraculous element” in that story. (It is more likely that Sarah was just pleased to be pregnant after 10 years of perceived infertility – the miraculous did not have to be increased.)
In Exodus, the P Source writer began by following the E Source account (and, according to the taste of the times, exaggerating its miraculous elements). Some of the rules in P for the Passover probably came from an Akkadian Source (but they also have been greatly elaborated). After this, P has commands about the construction and decoration of the tabernacle, almost certainly written after the destruction of the Jerusalem temple, but written with the intention that they would provide a blueprint for the re-establishment of the “inner tabernacle” after the hoped-for return of the nation to the land of Israel.
The rest of the P Source in Numbers and all of Leviticus reflects the P Source writer’s knowledge of the current Levitical rules. It also reveals his imaginative reconstruction of what Moses might have said and done more than 600 years earlier. This particular part has no historical value whatsoever.
Conclusion
Because the P Source presents itself as the most definitive and clearly constructed account of Israel’s history before the conquest of Canaan it dominates our understanding of the historical events. This is a pity, at least for the period of the Exodus and beyond, since it is of very little value as a historical resource for that period.
However, when we move back to Genesis, apart from its elaborations around the story of Abraham, it is very useful. Its direct use of the Akkadian Source material means that it has leap-frogged the colouring of the other sources (arising from their reliance on oral traditions), and given us something quite close to an eyewitness account of those times, at least from the perspective of Joseph’s family.