In Nephi's rehearsal of the meaning of his father's dream, we expect him to use the special knowledge he has so recently received in personal revelation. What we might not expect, however, is this verse. In addition to the logical ramifications of Lehi's dream, in addition to the specifics of the vision he as received, Nephi rehearses the words of Isaiah on the same topic. Where did Nephi learn the words of Isaiah to use in exegesis?
This verse gives us an interesting glimpse into the Nephi that is only implied. Unless major sections of Isaiah were part of his vision, and he neglected to so state, then Nephi was able to cite Isaiah before his vision. Nephi was prepared with the basic understanding of the scriptures before he even approached the Lord for explanation of his father's dream. When he received the meaning of the dream, that also provided a context into which he could place the scriptural learning he had already acquired.
In this passage, Nephi demonstrates that he is not one to whom everything was given simply for the asking. He evidently was quite well prepared with a scriptural background, which apparently gained clarity through what he learned in vision.
The result of Nephi's preaching was to humble his brothers. This is part of the sad pattern of Laman and Lemuel's experience with the Spirit. They were capable of being touched at times, but were unable to hold on to those feelings, and allowed their pride to fill their souls again after short bouts with humility.