In June 1828, Joseph Smith reluctantly allowed his scribe Martin Harris to borrow 116 pages of the original Book of Mormon manuscript. Harris promised to guard the pages and show them only to certain family members, but the pages soon disappeared and have never been recovered. Joseph sought divine guidance on how to proceed with the rest of the translation and learned by revelation how to complete the Book of Mormon translation without revisiting the text contained in the missing manuscript.

What little is known of the lost manuscript’s contents comes from Joseph Smith and the Book of Mormon prophet Nephi. Joseph wrote that the lost pages contained the book of Lehi. Like much of the Book of Mormon, the record of Lehi was an abridgment by the prophet Mormon of what Joseph called the plates of Lehi. Lehi’s son Nephi explained that this record contained accounts of Lehi’s dreams, visions, prophecies, and teachings to his children. Nephi had abridged Lehi’s record before composing his own history. According to some scholars, Nephi’s abridgment comprises the early chapters of the Book of Mormon. Others speculate the lost manuscript contained not only the book of Lehi but also material written by others, perhaps Mormon or someone who lived sometime between Lehi and King Benjamin.

At the time the manuscript disappeared, Joseph Smith and Martin Harris did not know of Nephi’s abridgment. As a result, when Joseph learned that Harris had lost the manuscript, Joseph thought he had failed in his divine commission. Joseph did not resume translating for about nine months. Later, when he and his new scribe, Oliver Cowdery, had nearly reached the end of the record, Joseph asked for revelation about whether to retranslate the lost pages. The revelation (see Doctrine and Covenants 10) said the plates of Nephi contained an account similar to the book of Lehi but with a greater focus on the spiritual history of Lehi’s family. Joseph learned that he should translate the plates of Nephi until he reached the place where the lost manuscript had ended. The revelation also forbade Joseph from retranslating the book of Lehi and warned him of adversaries possessing the lost manuscript who might attempt to manipulate the text and then discredit the published version of the Book of Mormon. Joseph worried so much about the possibility of an altered manuscript that in the preface of the Book of Mormon, he warned conspirators not to oppose God’s work. No one ever came forward with the lost manuscript.