Verses 1 and 2 perhaps belong better to the end of chapter 3 than the beginning of chapter 4, as they are Nephi's final summation of the message Lehi gave to Joseph wherein Lehi cited Joseph of Egypt's prophecies. Verse 2 makes it clear that the Joseph of Egypt prophecies were contained on the brass plates. The impact of the brass plates upon Lehi had been profound. Not only was the excursion to obtain them ordained of the Lord, but it was fraught with personal danger, and engendered great fear and anxiety on Lehi and Sariah as they awaited the return of their sons.
Upon receiving the plates, very clearly Lehi read them, and as his blessing to Joseph indicates, read them often enough that he not only understood them, but was able to cite from them. It is also evident from Nephi's comment that Nephi had also read the brass plates sufficient to understand the source of his father's citations.