According to Noel Reynolds, two decades before Lehi received the visions and revelations that sent him and his family into the wilderness, a manuscript now generally believed to have included all or part of the book of Deuteronomy was discovered in the temple at Jerusalem. This occurred during the 18th year of the reign of the righteous king Josiah (approximately 621 B.C.). After the discovery, Josiah went up to the temple with "all the people from the least to the greatest" and read the book to them, renewing the covenant contained therein in the presence of the Lord," and all the people pledged themselves to the covenant" (see 2 Kings 22-23, especially 23:1-3; see 2 Chronicles 34-35). The book and this event then provided the basis for Josiah's reforms by which he overthrew idol worship and centralized worship of Jehovah at the Jerusalem temple. Some of Lehi's own understanding of the covenant with Israel might have derived from that memorable event. The discovery of that version of Deuteronomy was without doubt the manuscript find of the century. It occurred while Lehi, an exceptionally literate and learned man in the prime of his life, lived in or near Jerusalem. Reynolds writes:
While I do not want to develop an account of the origin of the brass plates in this paper, I would note that it is even possible that the late-seventh-century discovery of this new text provided someone with the motivation to create the brass plates as an enlarged and corrected version of the Josephite scriptural record."
He makes this footnote:
John W. Welch suggests that the plates of brass might have been produced for King Josiah himself, after the discovery of Deuteronomy (see his study "Authorship of the Book of Isaiah," in Isaiah in the Book of Mormon, ed. Donald W. Parry and John W. Welch [Provo, Utah: FARMS, 1998], 430-32.
[Noel B. Reynolds, Lehi As Moses," in Journal of Book of Mormon Studies, Vol. 9, Num. 2, 2000, FARMS, pp. 27-28, 81]