According to Hugh Nibley, this prophecy has reference to the Old Testament going forth to the world. When Lehi said, "that these plates of brass should go forth unto all nations kindreds, tongues, and people" (1 Nephi 5:18), it was very shocking news, but it was fulfilled. The copies were made in Alexandria. That's were we got our Septuagint. It spread throughout the whole world from there, and all the world has the Bible now. Nobody ever dreamed that this local, national record would become the world record. Verse 19: "Wherefore, he said that these plates of brass should never perish; neither should they be dimmed any more by time. And he prophesied many things concerning his seed." Notice, this doesn't refer to the Book of Mormon; this refers to the brass plates. They are still bright. They have come down to us, and we still have them to this day. He said the records were "of great worth unto us." Why did they need them on the trip? Verse 21: ". . . that we could preserve the commandments of the Lord unto our children" (the commandments in the prophets, in the writings, and in the book of Moses). [Hugh W. Nibley, Teachings of the Book of Mormon, Semester 1, pp. 165-166] [See the commentary on 1 Nephi 5:11, also Alma 37:3-5]