All this has been forgotten today. Now higher criticism is considered a nefarious plot against chrstianity, and most people don't even know the traditional Jewish teaching that every single letter of the Torah comes directly from G-d (in fact it is forbidden to reject a single letter of the Torah). This is now actually considered a "chrstian" concept (Protestant, to be precise) and most people think Jews don't have a dog in that fight.
Well put..
I honestly am one who welcomes the additional data exposed by this source theory. But, I am also someone who believes that this text is one of the best preserved and keenly one of the most if not the most reliable history of all available texts in this world.
Just as in the "Christian" Bible, these sources when viewed in an accepting rather than rejecting context are complementary "witness" statements. Just as the exposition of the four disciples have deep contradictions, this is the nature of true witness statements rather than colluded fabrications that fear rather than proclaim and value truth. The two histories preserved into our modern five Books of Moses have been identified as stitching together of the records kept by the Northern Kingdom and the Southern Kingdom. Rather than omit a single word, the "Redactor" just folded these together side by side because no word was more replaceable or sacred and this was just passed to us as our inheritance. Both of the accounts agree on matters of substance but also vary in focus and nature of the text and narrative.
For some reason, I don't understand, people just look at these texts and their dating and say.. well these are too new. But, they know darn well, that the old records were on clay tablets and not sheep skin. Thus when the first Temple was destroyed, this old text and all of the lost books referred to in the transcriptions of this text were lost. Why is that such a mystery? For the people of that time it was a misery, but what can be done?
Archeology is slowly unearthing what support that is possible considering that there are people who want any evidence destroyed. They depend on people rejecting God so that they might continue to reap the wealth and power they achieve by the enslavement of people who don't understand that faith is the foundation of freedom.
The Bible as a whole is an amazing document. Like a fractal image, changing yet staying the same, bringing meaning in ways that people of all of the hundreds of generations from the time of Abraham could use in their own time. Abraham's relationship and understanding of God is just as hard to pass on today as it was in his time. But, he didn't have this wondrous text and the work of the brightest minds of every generation after to help him pass this to Isaac. We are infinitely blessed and this document is so much more than what a single human could accomplish, and a message aimed at the hearts of each living soul in each generation, and someone dares to claim that God couldn't accomplish this?
People who think this small only consider the pebbles in front of them and think they are the entirety of the wonders of this universe.
The Torah doesn't come from clay tablets, nor does it have multiple sources of any kind. According to Tradition the Torah was written entirely by G-d, 974 generations before the Creation. It actually preceded the universe and is in fact its "blueprint," its "DNA." In fact, one tradition insists that the universe was literally made from the letters of the 'Alef-Beit.
In the 26th generation of Creation, the Torah was given to Israel; HaShem dictated it letter-by-letter, and Moses wrote it down (there is an opinion that the narrative of Moses' death was written by Joshua, but Moses could in fact have taken down the dictation of his own death just as he took down the rest of the Torah). Even the medieval "arch-rationalist" Maimonides insisted in his Thirteen Principals of Faith that the entire Torah which Israel possesses was given to Moses. And some six hundred years later, another "arch-rationalist" (Vilna Ga'on) insisted that the Torah contains every fact about everything that has ever existed, whether human, animal, plant or mineral, and that it does so down to the smallest detail.
Moses wrote the first Torah Scrolls at HaShem's dictation and they have been faithfully copied since that time by scribes who follow the most rigorous rules, including one that commands them to have a complete kosher Torah Scroll before them as they transcribe. So there are no "sources" or "clay tablets." It all comes from G-d directly and unmediated.
The purest form of the Word of G-d is the Halakhically written kosher Torah Scrolls kept in the 'aronot of synagogues throughout the world and throughout history, not the texts that chrstian and atheist scholars use.