“I think we are agreed that it would take a great deal of training for anyone to acquire the background necessary to compose First Nephi. Now imagine any man insane enough to try after such colossal exertions to write another such story, of equal length and detail but this time about a totally different race of people, living in an age far removed from the other and in a wholly different geographical setting! As far as I know, not even Joseph Smith ever called anyone's attention to this prodigious feat; we all take it for granted.”
Our modern book of Ether is an English translation of Moroni’s abridgement of the Jaredite history (Ether 1:2). As explained in a previous installment, the Jaredite history was written by Ether the Jaredite on 24 metal plates that were discovered by the people of Limhi. Mosiah the younger, a Nephite prophet, interpreted these plates by way of a special stone (referred to in modern times as the “Urim and Thummim”) and Moroni felt inspired to add this record to his father’s abridgement of the Nephite record. While Moroni may have had access to the 24 metal plates, it seems more logical that Moroni drew his material from Mosiah’s translation of the Jaredite record.