Royal Skousen notes how the original manuscript of the Book of Mormon contains examples of the phrase “understand of” such as Mosiah 1:5
we might read and understand of his mysteries
Why wouldn’t Joseph Smith just say “understand his mysteries”? This usage of the word “of” is consistent with one usage in the Bible as well as Early Modern English.
Would Joseph Smith have known the Bible so well to notice this phrase in Nehemiah 13:7? Why do most people not know about it?