Section 10 is an amazing revelation. It teaches us about the power of repentance and forgiveness, the patience of the Lord, the reality of the adversary, our inability to judge people, and lots more.
In this post I'll focus on what the section tells us about the translation.
This section refers to the "plates of Nephi" five times.
Key point 1: These passages make no sense if Joseph wasn't using the plates to translate. If he was merely reading words that appeared on the stone in the hat (SITH), he wouldn't know or care what was in the stack of plates he obtained from Moroni's stone box in the hill Cumorah.
38 And now, verily I say unto you, that an account of those things that you have written, which have gone out of your hands, is engraven upon the plates of Nephi;
39 Yea, and you remember it was said in those writings that a more particular account was given of these things upon the plates of Nephi.
40 And now, because the account which is engraven upon the plates of Nephi is more particular concerning the things which, in my wisdom, I would bring to the knowledge of the people in this account—
41 Therefore, you shall translate the engravings which are on the plates of Nephi, down even till you come to the reign of king Benjamin, or until you come to that which you have translated, which you have retained;
45 Behold, there are many things engraven upon the plates of Nephi which do throw greater views upon my gospel; therefore, it is wisdom in me that you should translate this first part of the engravings of Nephi, and send forth in this work.
(Doctrine and Covenants 10:41-5)
Key point 2: Notice the references to the engravings on the plates (bolded above). The Lord specifically commanded Joseph to "translate the engravings." He did not say or imply that the translation would appear on a stone so Joseph could simply read it out loud.
In the context of Section 10, SITH is preposterous.
Not only did the Lord tell Joseph to "translate the engraving," but he got even more specific. He told him to translate "this first part of the engravings of Nephi." What part was that? It was "down even till you come to the reign of King Benjamin."
This passage shows us that Joseph had discretion in what parts of the plates to translate. If he was merely reading words off a stone, the Lord would not need to tell him what part of the plates to translate.
Key point 3: We can tell from Section 10 that Joseph did not yet have the plates of Nephi. The Title Page, which was on the last leaf of the plates he originally got from Moroni, listed the contents: the abridged record of the Nephites, the abridged record of the Jaredites, and Moroni's writings that sealed the record. No original plates of Nephi were included.
Verse 45 makes the distinction clear. The Lord told Joseph to translate the engravings of Nephi--Nephi's original writings, which were not in the abridged plates--and "send forth in this work."
What does "this work" refer to?
The translation of the abridged plates.
Recall Section 9, which also distinguished between "this record" (the abridged plates) and "other records," which turned out to be the plates of Nephi:
1 Behold, I say unto you, my son, that because you did not translate according to that which you desired of me, and did commence again to write for my servant, Joseph Smith, Jun., even so I would that ye should continue until you have finished this record, which I have entrusted unto him.
2 And then, behold, other records have I, that I will give unto you power that you may assist to translate.
(Doctrine and Covenants 9:1–2)
Key point 4: How did Joseph get the plates of Nephi? The Lord told Joseph and Oliver to translate the plates of Nephi, but they didn't have those plates in Harmony. Instead, they translated the plates of Nephi in Fayette at the Whitmer home.
Before leaving Harmony, Joseph gave the abridged plates to a divine messenger. On the way to Fayette, Joseph, Oliver and David Whitmer encountered the messenger on the road, who told them he was going to Cumorah. Joseph explained that this was one of the Three Nephites and he had the abridged plates. It makes perfect sense for the messenger to take the abridged plates back to the repository in Cumorah because Joseph had translated them all. From the repository, the messenger picked up the plates of Nephi and brought them to Fayette.
It's simple, really.
And an awesome confirmation that Joseph actually translated ancient plates.
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There are three common issues that arise from Section 10.
First, let's think about the warning that evil men would change the wording of the original translation of the book of Lehi (the 116 pages). I don't think there is any implication that they would modify the words on the 116 pages themselves. That would be obvious to anyone. Instead, the evil men would simply publish the changed version and say it was what Joseph translated. That would be plenty of "evidence" to support the bias against Joseph Smith.
Second, because Joseph was translating the engravings, he would not likely re-translate word-for-word. To expect him to do so would be unreasonable. Everyone knows, both now and back in 1828, that the Bible itself is subject to multiple translations. If Joseph had produced another translation that was similar to, but not identical to, the original one, that would be evidence that he actually translated. If he had produced another manuscript identical to the original 116 pages, that would be evidence that he was reading the words from a particular source. Therefore, the changes made by the evil men would have to be more substantive than just a few wording changes.
Third, one of the theological issues raised by the loss of the 116 pages is whether Martin Harris had free agency to take the plates. One traditional understanding of the events is that the Lord knew Martin would lose the 116 pages so He had Nephi prepare the "small plates" as a backup.
Years ago I was in a discussion about free agency vs predestination vs foreknowledge. I won't take the time to discuss all of that here, except to say that some people thought we had free agency, but others cited the traditional interpretation of D&C 10 to show that God knows far in advance what we'll do and therefore takes measures to offset our future actions. That sounds a lot like predestination; i.e., that Martin Harris was predestined to lose the plates.
There is another interpretation of D&C 10 and the lost 116 pages that does not require predestination (or the euphemism of foreknowledge).
Surely it was foreseeable that Joseph and/or his scribes could lose part of the translation. Therefore, there had to be a backup.
The original plates that Mormon abridged were available in the repository. Theoretically, no matter what Joseph or his scribes lost, the original records were always available. If Martin had lost, say, King Benjamin's sermon, the messenger could have gone into the repository to get the original version of that sermon and then bring those plates to Joseph.
But the point of the abridgment was to condense those records. To replace the Book of Lehi would involve re-abridging the records, a task that would be essentially impossible for Joseph within any reasonable time frame.
We can see in D&C 10 that the plates of Nephi (the "small plates") was not a duplicate of the Book of Lehi. It was different content because of Nephi's different emphasis.
We only have 1 Nephi through Words of Mormon because Martin Harris lost the 116 pages. Had he lost, say, Alma, we undoubtedly would have discovered that the Lord had prepared a separate backup for what was lost.
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Apart from the historical details, Section 10 shows us how forgiving the Lord is. Even though Martin Harris lost the 116 pages, he was allowed to serve as a scribe again. He was even allowed to be one of the Three Witnesses.
This teaches us that there is hope for all of us, despite our weaknesses and mistakes.
