If Nephi took the plates of Laban which contained the 5 books of Moses, how did the first books of the Old Testament get the same information contained on these plates as they were now out of reach of anyone in the Old World?
The Brass Plates of Laban were written in Egyptian hieroglyphics. They were very likely a rather ancient document in Lehi’s time, and could well have been the original scriptures.
This opinion may be deduced from the following information. When Moses was called by God to deliver the Israelites from bondage, he demurred, saying
O my lord, I am not eloquent, neither heretofore, nor since thou has spoken unto thy servant: bu I am slow of speech, and of a slow tongue. (Exodus 4:10)
So his brother, Aaron, was appointed as his spokesman.
What was Moses problem? Most opine that he had a speech impediment, but this is not the case. We learn from Acts 7:22, where Stephen, in defending himself before the Sanhedrin, and citing the history of Moses, says that
Moses was learned in all the wisdom of the Egyptians, and was mighty in words and in deeds. (Acts 7:22)
Moses problem was a simple one–he couldn’t speak Hebrew! As an infant he was taken in by Pharaoh’s daughter, was raised as a son of the Pharaoh and was being groomed to be the next Pharaoh. Josephus says of Moses that “being very skillful in making speeches, and having this natural talent among others, that he could greatly move the multitude with his discourses.” (Flavius Josephus, Antiquity of the Jews, IV, II, p 85)
When Moses was about 40 years old, in fear of being turned in to Pharaoh’s priests by a couple of the Hebrew Goshenites that he remonstrated for fighting, he fled to Midian where he spent the next 40 years, undoubtedly speaking a form of Arabic.
At this point he is called by God to lead the children of Israel out of Egypt. Moses wrote the first five books of the Bible. What language do you think that he used to record the sacred words of God? I would well image that he would have used the sacred writing form of his native Egyptian tongue–hieroglyphics.
If this were the case, the succeeding prophets would have had to learn Egyptian to read his writing and to teach “the law” to the Hebrew people. So it is possible that the Brass Plates of Laban were the very original scriptures– Moses’ writings in hieroglyphics added to by each of the succeeding prophets. (The fact that Lehi and Mosiah taught their sons to read Egyptian so that they could read the Brass Plates was very likely more of a tradition than a necessity).
However, the Jews from Goshen spoke Hebrew, and undoubtedly the hieroglyphics on the Brass Plates were soon translated into Hebrew so the various priests could teach the law and the prophets to the people. So the original scriptures were undoubtedly copied many times by the Hebrew scribes to make them available to the people.
Josephus, in his Antiquity of the Jews, took his information primarily from the Septuagint, a Greek translation of the Hebrew scriptures, developed over a 70-year period in the 3rd and 2nd centuries, B.C. But Josephus also rather frequently refers to “the sacred books” as sources of his information.
So the Hebrew scriptures were available to the people from very early times, and undoubtedly many copies had been made. These copies, of course, were hand written, and often reflected the apostate leanings of the recreant Jewish scribes. For this reason it is stated in the Articles of Faith of the Mormon Church that We believe the Bible to be the word of God as far as it is translated correctly.