1 Nephi 3:17 - 3:21
1 Nephi 3:17 - For he knew that Jerusalem must be destroyed, because of the wickedness of the people.
Nephi tells the boys that the reason that their father left Jerusalem was because it would be destroyed. The wickedness of the people would be the cause. I can just envision Laman and Lemuel rolling their eyes again saying that their father was nuts thinking that Jerusalem could possibility be destroyed.
1 Nephi 3:18 - 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.
Nephi tells his brothers that the people of Jerusalem have turned down the warnings of the prophets. They have considered their words to be that of crazy people who do not know of what they are talking about. If the family would have remained in Jerusalem, they would be destroyed along with very one else. To save the lives of his family, Lehi needed to escape while it was possible.
1 Nephi 3:19 - 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;
And since they were going to leave Jerusalem and never return, they needed to take books and records to have in their new home. This would preserve their language and culture.
This was going to be their home library. They would use it to teach their children how to read as well as of the works of the Lord. In pioneer days, people had few books. If they had a book it was probably the bible. And those who wanted to teach their children or the children who wanted to learn to read often use the bible as their text book. Schooling was sporadic and because of the need for all members of a family to work, there was little chance for a full education. So whatever books were in the home were used. Again the bible probably was the book they used.
1 Nephi 3:20 - And also that we may preserve unto them the words which have been spoken by the mouth of all the holy prophets, which have been delivered unto them by the Spirit and power of God, since the world began, even down unto this present time.
In addition, it would be a reference for the family and their descendants of what the prophets had written since the beginning of the world. And since the words are the product of the Spirit revealing them to men, they are in themselves very valuable.
They are the instructions for life and how to live it properly. These records would be absolutely vital to governing their lives in a new location. Without records they would become a primitive people without a bases for governing their behavior to one another and those who they might come across in their new home.
1 Nephi 3:21 - And it came to pass that after this manner of language did I persuade my brethren, that they might be faithful in keeping the commandments of God.
These were the arguments Nephi use to convinced his brothers that they needed to try again to get the brass plates from Laban.
