Here Stanford explores the pervasive and archaic use of "did" in the Book of Mormon, particularly the "affirmative declarative periphrastic" did, or ADP did. Brace yourselves for some intense grammar and loads of intriguing data showing that the unusual usage of this grammatical form in the Book of Mormon strongly differs from the King James Bible and other books available to Joseph Smith, and differs strongly from the English of Joseph Smith's day, but is consistent with EModE patterns a few decades before the KJV was produced. There is a remarkable fingerprint in the Book of Mormon that defies common efforts to ascribe the Book of Mormon to Joseph Smith's authorship.
Here is Stanford's abstract:
Abstract: In the middle of the 16th century there was a short-lived surge in the use of the auxiliary did to express the affirmative past tense in English, as in Moroni «did arrive» with his army to the land of Bountiful (Alma 52:18). The 1829 Book of Mormon contains nearly 2,000 instances of this particular syntax, using it 27% of the time in past-tense contexts. The 1611 King James Bible — which borrowed heavily from Tyndale’s biblical translations of the 1520s and ’30s — employs this syntax less than 2% of the time. While the Book of Mormon’s rate is significantly higher than the Bible’s, it is close to what is found in other English-language texts written mainly in the mid- to late 1500s. And the usage died out in the 1700s. So the Book of Mormon is unique for its time — this is especially apparent when features of adjacency, inversion, and intervening adverbial use are considered. Textual evidence and syntactic analysis argue strongly against both 19th-century composition and an imitative effort based on King James English. Book of Mormon past-tense syntax could have been achieved only by following the use of largely inaccessible 16th-century writings. But mimicry of lost syntax is difficult if not impossible, and so later writers who consciously sought to imitate biblical style failed to match its did-usage at a deep, systematic level. This includes Ethan Smith who in 1823 wrote View of the Hebrews, a text very different from both the Bible and the Book of Mormon in this respect. The same may be said about Hunt’s The Late War and Snowden’s The American Revolution.