(Warning: The views expressed in this post are Jewish, but not Orthodox. If reading non-Orthodox Torah makes you angry, please do not read this post. Also, you are advised to take a razor blade to your mikraot gedolot and excise much of the Ibn Ezra, some of the Siforno and Abravanel, and select Rashis and Rambans. (I don't mean to suggest that anyone at anytime would ever endorse what I am about to say --only that some of the classic commentary is similarly "Jewish, but not Orthodox."))
At the end of this week's parsha, we meet Amelek, eternal enemy of the Jewish people. Immediately after this encounter (at the very beginning of next week's parsha) we meet Yithro, respected friend and giver of good advice. Umberto Cassuto tells us these two stories stand in "neat antithesis" to one another, saying that while Amelek was fierce and came for war, Yithro the Midianite came in peace. Cassuto makes his case stronger by pointing to certain keywords, as follows:
-- When Amalek arrives, men are chosen for war (וַיֹּאמֶר מֹשֶׁה אֶל-יְהוֹשֻׁעַ בְּחַר-לָנוּ אֲנָשִׁים) After Yithro arrives men are chosen to be judges:(וַיִּבְחַר מֹשֶׁה אַנְשֵׁי-חַיִל מִכָּל-יִשְׂרָאֵל)
-- During the battle with Amelek Moshe sits on a stone (וַיִּקְחוּ-אֶבֶן וַיָּשִׂימוּ תַחְתָּיו וַיֵּשֶׁב עָלֶיהָ) Later he sits in judgement (וַיֵּשֶׁב מֹשֶׁה, לִשְׁפֹּט אֶת-הָעָם)
-- At first Moshe's hands are heavy (וִידֵי מֹשֶׁה כְּבֵדִים) Later the burden of judging is described with the same word (כִּי-כָבֵד מִמְּךָ הַדָּבָר)
Cassuto's point is that an author (whether the author was God, as I believe, or a redactor) makes certain choices. He choses to tell His story in a certain way, using certain words, for certain literary reasons. And the fact that these choices can be observed tells us that the Torah is a literary whole - at least in such places where those choices are apparent.
I like this type of observation because (I think) it confounds the DH idea that the Torah is crazy quilt of literary traditions, unreflectivly stitched together by a redactor. Now many of you will be quick to point out that this type of study doesn't prove that the Torah was given by God (as I believe it was.) Also, it does not rule out the possibility that maculations were later introduced into the text.
However, I think even skeptics must concede that observations such as this suggest (rather strongly in my opinion) that the Torah was (for the most part) finalized by one hand, a hand that made deliberate and purposeful authorial choices.
(And why couldn't that hand have belonged to God?)