In 1830, shortly after the Book of Mormon was printed, Joseph Smith embarked on what would later be called the Joseph Smith Translation (JST) of the Bible. In short, it was an attempt to retranslate and correct the text. The original manuscript belongs to the RLDS Church.
The LDS Church has not canonized the work and includes only brief footnote citations in its standard works. A recent BYU study has uncovered striking parallels between Smith’s work and Adam Clarke’s popular Bible commentaries of the same period.
IMPORTANCE OF THE WORK
The LDS Church refers to the work as an “inspired translation.” Joseph himself regularly referred to the work as a translation, such as: “I completed the translation and review of the New Testament on the 2nd of February, 1833, and sealed it up, no more to be opened till it arrived in Zion.”  When the Church updated its version of the King James Bible in 1979, it said the translation “…forms an important part of new LDS editions of the scriptures.”
Various Church authorities have reaffirmed the significance of the JST. Bruce McConkie instructed: “The Joseph Smith Translation, or Inspired Version, is a thousand times over the best Bible now existing on earth. It contains all that the King James Version does, plus pages of additions and corrections and an occasional deletion. It was made by the spirit of revelation, and the changes and additions are the equivalent of the revealed word in the Book of Mormon and the Doctrine and Covenants. For historical and other reasons there have been, among some members of the Church in times past, some prejudice and misunderstanding of the place of the Joseph Smith Translation. I hope this has now all vanished away.” 
An LDS Ensign article asserted “…the work was to be a revelatory experience, through which Joseph would come to an understanding of things that he had not previously known.” 
Robert J. Matthews, former dean of Religious Instruction at BYU, suggested in an Ensign article “…failure to publish the new translation was not due to any negligence or lack of interest on Joseph Smith’s part, but rather to a neglect on the part of the Saints to provide the temporal necessities by which the Prophet could attend to the work. The story is fascinating and meaningful, with important lessons to be learned, not the least of which is that when an opportunity presents itself to render service to a prophet doing the Lord’s work, we should act without delay or the opportunity may pass unfulfilled.” 
As the meaning of the word “translate” has come under increased scrutiny among members of the Church, it is relevant to explore Joseph Smith’s own claims regarding his translation of the Bible.
The introduction to the JST suggests that “Because the Lord revealed to Joseph certain truths that the original authors had once recorded, the Joseph Smith Translation is unlike any other Bible translation in the world. In this sense, the word translation is used in a broader and different way than usual, for Joseph’s translation was more revelation than literal translation from one language into another.”
The Church today emphasizes that “Joseph’s translation was not carried out in the traditional sense…he used the King James Version of the Bible as his starting point and made additions and changes as he was directed by the Holy Ghost.” 
BYU PROVIDES NEW INSIGHTS
Recently, Dr. Thomas Wayment, a professor of ancient scripture at BYU, and Haley Wilson Lemmon, “…uncovered evidence that Smith and his associates used a readily available Bible commentary…” They point out that “Adam Clarke’s famous Holy Bible, Containing the Old and New Testaments, was a mainstay for Methodist theologians and biblical scholars alike, and was one of the most widely available commentaries in the mid-1820s and 1830s in America,” and argue “that Clarke is the primary source Smith used.”
Clarke published his summaries in a series between 1808 – 1826, before passing away in 1832. In July 1832, Joseph Smith wrote to W. W. Phelps, stating “we have finished the translation of the New Testament.”
“Our research has revealed that the number of direct parallels between Smith’s translation and Adam Clarke’s biblical commentary are simply too numerous and explicit to posit happenstance or coincidental overlap. The parallels between the two texts number into the hundreds, a number that is well beyond the limits of this paper to discuss. A few of them, however, demonstrate Smith’s open reliance upon Clarke and establish that he was inclined to lean on Clarke’s commentary for matters of history, textual questions, clarification of wording, and theological nuance. In presenting the evidence, we have attempted to both establish that Smith drew upon Clarke, likely at the urging of Rigdon, and we present here a broad categorization of the types of changes that Smith made when he used Clarke as a source.” 
Smith’s reliance upon Clarke’s work seems unavoidable and reignites questions surrounding his apparent use of contemporary source materials to craft his narratives. The parallels to Clarke identified in the JST beg the question of the scribes’ role in his various “translation” processes.
SOURCE OF JAREDITE ROCKS
The recently discovered connections between Adam Clarke’s Bible summaries and Joseph Smith’s work has prompted increased scrutiny and comparisons of the two author’s works. It is fascinating to discover the following in Clarke’s summary of Genesis 6:16, dealing with the construction of Noah’s ark. Could Clarke’s words be the catalyst for windows and glowing rocks in Jaredite barges? Recall that the notion of transparent windows would have been unknown to ancient Hebrews.
“A window shalt thou make… The original word צהרtsohar signifies clear or bright…which plainly shows they did not understand the word as signifying any kind of window or light…a transparency…supposes that it was a precious luminous stone which Noah, by Divine command, brought from the river Pison. It is probably a word which should be taken in a collective sense, signifying apertures for air and light.”
- Rethinking Joseph Smith’s Bible Translation, BYU Journal of Undergraduate Research, Haley Lemmon and Thomas Wayment
- MormonThink – Joseph Smith Translation
- Haley Lemmon – The JST – Revelation or Plagiarism: Mormon Discussion podcast 299
LDS Discussions: BYU Study of the Plagiarism of Adam Clarke’s Work
- LDS Perspectives, Episode 55 – Thomas Wayment Interview
- Thoughts on Things and Stuff – Tracking Changes of the JST
- Adam Clarke’s Bible commentaries
 The Bible, a Sealed Book, Bruce R. McConkie, LDS.org.
 Joseph Smith’s Inspired Translation of the Bible, Ensign 1972.
 Joseph Smith’s Efforts to Publish HIs Bible Translation, Ensign, Jan 1983.
 JST Bible Translation, lds.org
 A Recently Recovered Source: Rethinking Joseph Smith’s Bible Translation, BYU.edu