1 Nephi 19:3
3 And after I had made these plates by way of commandment, I, Nephi, received a commandment that the ministry and the prophecies, the more plain and precious parts of them, should be written upon these plates; and that the things which were written should be kept for the instruction of my people, who should possess the land, and also for other wise purposes, which purposes are known unto the Lord.
Nephi kept everything that was important on his original large plates. They contained “the record of my father [he mentions his father’s journal twice], and also our journeyings in the wilderness, and the prophecies of my father; and also many of mine own prophecies…and the genealogy of his fathers [so he had also copied a good deal from the Brass Plates], and the more part of all our proceedings in the wilderness.”
It appears that “journeyings” were their travels, and “proceedings” were what they did when they stopped in the various places. They spent eight years to traverse the distance of a typical four month’s journey, so there would have been a lot of story to tell. His writing the information on plates indicates that Nephi believed he was doing a necessary, permanent, and probably final job of it.
Before we assume that the Small Plates are just an abridgement of the Large Plates, we ought to ask, What were the Small Plates for? The answer we usually give is that when Mormon was working on his own history, he found these plates and decided that for some reason that he didn’t know, he would stick them on at the end of his own work. The Lord had known, 2,500 years before, that they would be needed because Martin Harris would lose the precious 116 page of manuscript (D&C 10:38-42).
Nephi tells us the Lord instructed him that the Small Plates should contain an account of “the ministry and the prophecies, the more plain and precious parts of them, should be written upon these plates.” That can be read: “plain-and-precious” or “plain” and “precious.” If the latter, it again calls attention to the double languages in which Nephi wrote First and Second Nephi. There are some things that are so sacred that if they are lost, their loss virtually signals the closing of that dispensation of the gospel. Interestingly, those most sacred things that must not be forgotten are also the things that must not be written, except, of course, in places that are carefully guarded—guarded physically or by a code language. Nephi seems to be saying both.
Nephi’s instructions to his successors were that the plates “should be handed down from one generation to another, or from one prophet to another, until further commandments of the Lord.” In ancient Israel the chief prophet was often the king (as it was with Nephi and Benjamin), but, as in Judah, the early Nephite kings apostatized, so apparently to avoid the loss or alteration of the Small Plates, they were to be kept by the descendants of Jacob until they could safely become a part of the royal regalia.