Is it true that the Nephites and Lamanites did not have access to the writings on the gold plates? The writings of their prophets? It is my understanding that they used only the brass plates for scripture references.
The gold plates refer to the abridgment provided by Mormon/Moroni which Joseph Smith later translated into what we have now as the Book of Mormon. The plates of brass refer to the plates retrieved by Nephi and his brothers from Laban. The Nephites therefore, would have never had access to the gold plates; however, the teachings within the gold plates were surely taught to the people of Nephi.
In the beginning, the plates of brass would have been the sole source of scriptural references for them to study; however the words of Nephi give us further insight when he declared (2 Nephi 25:26),
“And we talk of Christ, we rejoice in Christ, we preach of Christ, we prophesy of Christ, and we write according to our prophecies, that our children may know to what source they may look for a remission of their sins (emphasis added).”
The Nephites were commanded of the Lord to write down their prophecies, and their revelations, as they taught important truths pertaining to salvation.
A second witness is provided by Jacob as he declared (Jacob 4:2),
“But whatsoever things we write upon anything save it be upon plates must perish and vanish away; but we can write a few words upon plates, which will give our children, and also our beloved brethren, a small degree of knowledge concerning us, or concerning their fathers (emphasis added).”
This verse teaches that they wrote their revelations and prophecies upon other plates.
The plates of brass could be likened to our canon of scripture today — our quads. Although we have our quads (our sole source of scripture — canon), we have plenty of other writings which can be considered scripture also: Ensign (Prophets & Apostles writings), General Conference. We see a similar trend within the Book of Mormon as shown here (Alma 18:38),
“And he also rehearsed unto them concerning the rebellions of Laman and Lemuel, and the sons of Ishmael, yea, all their rebellions did he relate unto them; and he expounded unto them all the records and scriptures from the time that Lehi left Jerusalem down to the present time (emphasis added).”
Scriptures which were received at that present time were expounded upon.
When the Lord visited his people upon the American continent, the Lord declared (3 Nephi 23:6), “And now it came to pass that when Jesus had said these words he said unto them again, after he had expounded all the scriptures unto them which they had received, he said unto them: Behold, other scriptures I would that ye should write, that ye have not (emphasis added).” The Lord, as commanded by his Father, provides this people with other scripture which they had not (3 Nephi 26:2).
The plates of brass were similar to our canon today — a corner stone to all other teachings, and as we have received additional scripture (Article of Faith #9), it is clear that so did the Nephites by which they taught, expounded, and convinced the children of God concerning the coming of Christ.