What is your position on the authorship of Genesis?
An impressive array of evidences for the seeming heterogeneity of sources within the first five books of the Bible have converged to form the basis of the Documentary Hypothesis, a broad scholarly consensus whose most able current popular expositor has been Richard Friedman.
However, even those who find the Documentary Hypothesis compelling have good reason to admire the resulting literary product on its own terms. For example, in the case of the two Creation chapters, Friedman himself writes that in the scriptural version of Genesis we have a text "that is greater than the sum of its parts" (R. E. Friedman, Commentary, p. 16). Sailhamer aptly summarizes the situation when he writes that "Genesis is characterized by both an easily discernible unity and a noticeable lack of uniformity" (J. H. Sailhamer, Genesis, p. 5).
For the purposes of the commentary, I have treated the book of Moses from a canonical perspective, ignoring the rather complex questions about how primary sources in Genesis may have been written and combined to form the scriptural text as we now have it. The idea that a series of authors may have had a hand in the authorship of Genesis should not be foreign to readers of the Book of Mormon, where inspired editors have explicitly revealed the process by which they wove separate overlapping records into the finished scriptural narrative.
In contrast to the carefully controlled prophetic redaction of the Book of Mormon, however, we do not know how much of the editing of the Old Testament may have taken place with less inspiration and authority. Joseph Smith wrote: "I believe the Bible as it read when it came from the pen of the original writers. Ignorant translators, careless transcribers, or designing and corrupt priests have committed many errors" (J. Smith, Jr., Teachings, 15 October 1843, p. 327).
Is the book of Moses in its "final" form?
While I do not think it is necessary to believe that every word in our book of Genesis came from the pen of Moses, both study and personal witness have confirmed to me that Joseph Smith made his revisions as the result of a prophetic mandate from God. This being said, I think it would be a mistake to assume that this work of scripture is currently in any sort of "final" form, if indeed such perfection in expression could ever be achieved within the confines of our "little, narrow prison, almost as it were, total darkness of paper, pen and ink; and a crooked, broken, scattered and imperfect language" (J. Smith, Jr., Documentary History, 27 November 1832, 1:299). As Robert J. Matthews, the foremost scholar on the Joseph Smith Translation (JST), aptly put it, "any part of the translation might have been further touched upon and improved by additional revelation and emendation by the Prophet" (Plainer, p. 15).
Though Joseph Smith was careful in his efforts to render a faithful translation, he was no naïve advocate of the inerrancy or finality of scriptural language. Although in some cases in his Bible translation he resolved blatant inconsistencies among different accounts of the Creation and the life of Christ, he did not attempt to merge them into single, final harmonizations. Differences in perspective, and even seeming inconsistencies between such accounts, composed "in [our] weakness, after the manner of [our] language, that [we] might come to understanding" (D&C 1:24), can be an aid rather than a hindrance to human comprehension, perhaps serving disparate sets of readers or purposes.
Moreover, in Joseph Smith's translation of these accounts, his criterion for acceptance was generally pragmatic rather than absolutistic in nature. For example, in rendering a particular verse in Malachi he admitted that he "might have rendered a plainer translation," but in this case was satisfied so long as the words were "sufficiently plain to suit [the] purpose as it stands" (D&C 128:18). This approach is also evident in his renderings of key verses of scripture in his discourses, where he often varied the wording in order to better bring out some point he was making.
There is another reason why I am reluctant to think of the book of Moses as being in its "final" form. My own study of the translations, teachings, and revelations of Joseph Smith has convinced me that he sometimes knew early on much more about certain matters than he taught publicly. Indeed, in some cases, we know that the Prophet deliberately delayed the publication of early temple-related revelations connected with his work on the JST until the later Nauvoo period. For example, in Bachman's groundbreaking studies on the origins of D&C 132—which has not only to do with celestial marriage but also the whole context of temple work—he convincingly argued that nearly all of that section was revealed to the Prophet in 1831 as he worked on the JST. This was more than a decade previous to 1843, when the revelation was first recorded (D. W. Bachman, New Light). Likewise, Joseph Smith waited until 1843 to publish the first chapter of the book of Moses. In that revelation, he had been specifically commanded not to show it "unto any except them that believe until I command you" (Moses 1:42). Some of what the Prophet learned as he worked on the JST and other translation projects may have never been put into writing (see, e.g., Book of Abraham, Facsimile 2, explanations of figures 8-22). Brigham Young is remembered as stating "that the Prophet before his death [spoke] about going through the translation of the scriptures again and perfecting it upon points of doctrine which the Lord had restrained him from giving in plainness and fulness at the time" (cited in G. Q. Cannon, Life, pp. 147-148).
Even after Joseph Smith was well along in the translation process, he seems to have believed that God did not intend for him to publish the JST in his lifetime. Writing to W. W. Phelps on 31 July 1832, he said: "I would inform you that [the Bible translation] will not go from under my hand during my natural life for correction, revisal, or printing and the will of [the] Lord be done" (J. Smith, Jr., Writings 2002, p. 273). Although he later reversed his position and made serious efforts to prepare the 1833 manuscript of the JST for publication, the statement implies that, at least during the early part of his ministry, he did not feel authorized to share all that he had learned during the translation process.
Does the book of Moses restore the "original" version of Genesis?
LDS teachings and scripture clearly imply that Moses learned of the Creation and the Fall in vision and was told to write it. Moreover, there are revelatory passages in the book of Moses that have remarkable congruences with ancient texts. However, I think it would be unwise to rely on JST Genesis as a means for uncovering a Moses Urtext. Even if certain revelatory passages in the book of Moses were found to be direct translations of ancient documents—as was, apparently, D&C 7—it would be very difficult to establish whether or not they once existed as an actual part of some sort of "original" manuscript of Genesis.
During the process of translation, Joseph Smith made several types of changes, running the gamut from "long revealed additions that have little or no biblical parallel, such as the visions of Moses and Enoch, and the passage on Melchizedek," to "common-sense" changes and interpretive additions, to "grammatical improvements, technical clarifications, and modernization of terms"—the latter being the most common type of change (P. L. Barlow, Bible, pp. 51-53). Also, of great interest, is the hypothesis that the book of Moses contains features that qualify it, at least in part, as a "temple text" (J. M. Bradshaw, In God's Image, pp. 342-344).
Of course, even in the case of passages that seem to be explicitly revelatory, it remained to the Prophet to exercise considerable personal effort in rendering these experiences into words (cf. D&C 9:7-9). As Kathleen Flake puts it, he did not see himself as "God's stenographer. Rather, he was an interpreting reader, and God the confirming authority" (K. Flake, Translating Time, pp. 507-508; cf. G. Underwood, Revelation, pp. 76-81, 83-84).
With respect to the English translation of the Book of Mormon, Royal Skousen argues that the actual choice of words chosen was given under "tight control" (R. Skousen, Tight Control). By way of contrast, however, Skousen questions whether one should assume that every change made in the JST constitutes revealed text. Besides arguments that can be made on the basis of the modifications themselves, there are questions regarding the reliability of, and degree of, supervision given to the scribes who were involved in transcribing, copying, and preparing the text for publication. Differences are also apparent in the nature of the translation process that took place at different stages of the work. For example, while a significant proportion of the Genesis passages that have been canonized as the book of Moses "[look] like a word-for-word revealed text," evidence from a study of two sections in the New Testament that were translated twice indicates that the later "New Testament JST is not being revealed word-for-word, but largely depends upon Joseph Smith's varying responses to the same difficulties in the text" (R. Skousen, Earliest, pp. 456-470. For the original study, see K. P. Jackson, et al., Two Passages.).
For all these reasons, LDS scholars should be cautious in any claims that the JST as a whole constitutes a restoration of the "original" form of scripture.
So, in summary, what is the book of Moses?
I believe that the Moses 1 was a more or less word-for-word revelation under tight control. I also believe that both Moses and Joseph Smith received visions of what the Creation and the Fall. Lorenzo Brown remembered Joseph Smith as saying:
"After I got through translating the Book of Mormon, I took up the Bible to read with the Urim and Thummim. I read the first chapter of Genesis, and I saw the things as they were done, I turned over the next and the next, and the whole passed before me like a grand panorama; and so on chapter after chapter until I read the whole of it. I saw it all!" (Lorenzo Brown in "Sayings of Joseph, by Those Who Heard Him at Different Times," Joseph Smith Jr. Papers, Church Archives, The Church of Jesus Christ of Latter-day Saints, Salt Lake City, UT, cited in K. Flake, Translating Time, p. 506 n. 31. Flake notes: "Brown's statement is based on his recollection in 1880 of a conversation that occurred in 1832. For questions concerning the reliability of this account, see R. J. Matthews, Plainer Translation, pp. 25-26, n. 12.")
This being said, I don't believe that Joseph Smith directly recorded all that he saw with respect to these chapters, at least partly because of the sacredness of the events. Rather, he added selected prophetic insights, as well as, in some cases word-for-word revelation (e.g., story of the sacrifice of Adam, accounts of Enoch), directly into the biblical Genesis account. Even with respect to the limited, partial version that he recorded, he was told to keep it sacred (see e.g., Moses 1:42, 4:32).
As a result of Joseph Smith's revelatory translation efforts, we are given enough revised and expanded material to further highlight the many temple themes in the book of Moses, but not so much as to radically rework Genesis to the point it is unrecognizable. It seems entirely plausible to me that, as Joseph Smith is purported to have said, he intended to go back and at least rework some portions of the translation to add in truths he was previously restricted from giving in plainness.
At this point, all the opinions I express above are based on very limited evidence. I hope that in the future, more light will be thrown on these topics.