In Mormonism, the Large Plates of Nephi (pronounced nee-fie) are alleged to be a collection of writings created by ancient inhabitants of the American Continent. Mormons believe that some of these writings were compiled and abridged by a prophet named Mormon along with his son Moroni, into a single record. They believe that this record was translated by Joseph Smith and is now available as The Book of Mormon.
Narrative
According to the doctrine of The Church of Jesus Christ of Latter-day Saints, Nephi was a prophet who, along with his family and a few others, left Jerusalem and came to the New World. Once they arrived there, he was given the task of keeping a record of the spiritual state of his posterity; and also a record of the socio-political environment. Additionally, he was to cause the records to be handed down, and maintained, from generation to generation.
To fulfill these obligations, Nephi created two sets of metal plates, upon which he and those who inherited the burden could engrave the appropriate text. One set of plates was called the Small Plates of Nephi. They were designed to hold the spiritual record of the people. The other was called the Large Plates of Nephi. Those plates were to be used for the history of the people: their wars, kings, etc.
In the Book of Mormon, the latter divisions (which are called books), starting with Mosiah and ending with Mormon (up to, and including, chapter 7), are said to be a translation of Mormon’s abridgment of the Large Plates of Nephi
External links
A Brief Explanation of the Book of Mormon (http://scriptures.lds.org/bm/explntn) on the lds.org website
Nephi, as the head of the political aspect of his people, would have been the one to sanctify the plates by his possession of them and the rulership.
Nephi begins to make the distinction between the content value of the official Plates of Nephi (known to us as the largeplates of Nephi) and the unofficial plates (small "p") of Nephi (known to us as the small plates of Nephi).
Nephi is now finished with his brief description of the textual sources, has explained why the small plates are unique, and perhaps has justified them as his own personal account.