1 Nephi 3:19

19 And behold, it is wisdom in God that we should obtain these records, that we may preserve unto our children the language of our fathers;

Here Nephi reveals to his brothers the reasons for, and importance of retrieving the brass plates. The first reason he gives is language preservation. Language tends to degrade (or progress, depending on your point of view) over time even with written records available. We can easily see that here in the United States. After just over 380 years (from 1620 – the pilgrims’ landing) we no longer speak English. We speak American, whose roots are English, but have been altered over time by lots of influences, such as immigration and slang. Those who don’t read the Bible, for example, have a hard time understanding that language. The King James Version of the Bible uses an older language that is not generally spoken any more. So some of the more subtle meanings tend to get lost unless you make it a subject of intense study that takes you into the culture and understanding the more archaic expressions used. Another consequence is that in an effort to modernize the language in scripture some mistranslations can occur, changing the intended meaning. By going back to the original KJV (and other writings of the time) time and again, we slow down the changes in our language.

The Mulekites left Jerusalem around the same time the Lehites did, yet in that same amount of time their language had changed to the point that when the Nephites discovered them (about the same amount of time since the Pilgrims arrived in North America), they could not understand one another. Both groups left Jerusalem at about the same time, so the only real difference was that Lehi brought records, and Mulek did not. (see Omni 1:17)

1 Nephi 3:18

18 For behold, they have rejected the words of the prophets. Wherefore, if my father should dwell in the land after he hath been commanded to flee out of the land, behold, he would also perish. Wherefore, it must needs be that he flee out of the land.

Verse 17 tells us that Jerusalem has to be destroyed because of the wickedness of the people. Verse 18 tells us that rejecting the words of the prophets is the last straw. They obviously were doing more than just disobeying the prophets, or they wouldn’t have been called to cry repentance so strongly. Rejecting the prophets is a sure sign that you have no intention of repenting. Jeremiah, a contemporary of Lehi, records how the Jews chased a prophet all the way to Egypt, just to bring him back to Jerusalem and kill him. (Jeremiah 26:21–24) That is far more serious than merely disobeying the prophets. That's going out of your way to not only disobey, but kill them.

These prophets were subject to their own prophecies, of course. If Lehi had not left Jerusalem as commanded, he would have been killed, either because the people were killing prophets, or by not leaving he would have experienced the same fate as the rest of Jerusalem because he didn’t heed his own warnings.

1 Nephi 3:17

17 For he knew that Jerusalem must be destroyed, because of the wickedness of the people.

Jerusalem’s destruction is now a matter of record, but at the time Lehi and his fellow prophets were being persecuted, their prophecies about that destruction was one of the things that got them (the prophets) into trouble.

1 Nephi 3:16

16 Wherefore, let us be faithful in keeping the commandments of the Lord; therefore let us go down to the land of our father’s inheritance, for behold he left gold and silver, and all manner of riches. And all this he hath done because of the commandments of the Lord.

The next logical step, if Laban wouldn’t donate the records, was to try buying them. Lehi was a wealthy man, and he left all that wealth behind according to the Lord’s commandment. So Nephi and his brothers had some resources with which they could purchase most anything they wanted. They could also make a good offer for the plates. All that wealth would have been no good to them anyway when Jerusalem fell, so Lehi left it behind.

In our own personal journeys to the “Promised Land,” our temporal, earthly wealth is of little value except as it is used in the service to God.

1 Nephi 3:14–15

14 But Laman fled out of his presence, and told the things which Laban had done, unto us. And we began to be exceedingly sorrowful, and my brethren were about to return unto my father in the wilderness.

15 But behold I said unto them that: As the Lord liveth, and as we live, we will not go down unto our father in the wilderness until we have accomplished the thing which the Lord hath commanded us.

After Laman returns and tells how things went with Laban, they began to sorrow. I imagine everyone was sorrowing for different reasons. Nephi and Sam may have been sorrowing that this task would not be as easy as they hoped; Laman and Lemuel were probably upset about the wasted trip. They wanted to go home after one try. This is when Nephi begins to rule over his brethren as the Lord had promised him he would. (1 Nephi 2:22) Nephi starts into a speech about how they need to be more faithful and keep the promise they made to the Lord to retrieve the plates. He kind of shames them into doing the right thing. In the end, Nephi prevails with his idea to buy the plates. Notice that Nephi is very careful to say the Lord had commanded them. It was very clear in his mind that they were on the Lord’s errand, not Lehi’s. I don’t think Laman and Lemuel quite understood or believed that. I think they were on this trip for their father, not for the Lord.

1 Nephi 3:13

13 And behold, it came to pass that Laban was angry, and thrust him out from his presence; and he would not that he should have the records. Wherefore, he said unto him: Behold thou art a robber, and I will slay thee.

It seems like these records must have been pretty important to Laban. I wonder why he got so angry at Laman and accused him of being a robber when he simply requested the plates. Surely Laban didn’t care that strongly about the records of the prophets that were contained thereon. It must be the genealogy that he was so protective of. Or the artifact itself due to its value.

1 Nephi 3:10–12

10 And it came to pass that when we had gone up to the land of Jerusalem, I and my brethren did consult one with another.

11 And we cast lots—who of us should go in unto the house of Laban. And it came to pass that the lot fell upon Laman; and Laman went in unto the house of Laban, and he talked with him as he sat in his house.

12 And he desired of Laban the records which were engraven upon the plates of brass, which contained the genealogy of my father.

Apparently none of the brothers was all that excited about facing Laban to ask for the plates, otherwise there would have been volunteers. But instead they cast lots, a way to make a random choice. Interesting that the lot fell on Laman, who, being the oldest, should have been the volunteer. Was it coincidence that Laman was chosen? Maybe, but Proverbs 16:33 seems to indicate that the Lord has the final say about how the lot is cast. Either way we need to again give Laman credit here. He obviously didn’t want to go in the first place, but not only did he make the trip, he went in to Laban alone when the lot was cast in his favor. And I think he did the reasonable thing. He gave Laban the opportunity to do the Lord’s will first on his own accord.