In overview, beginning in 2 Nephi 25, Nephi spoke "somewhat concerning the words which I have written, which have been spoken by the mouth of Isaiah" (25:1). That set of interpretive sayings continues on until the end of chapter 30. I imagine that Nephi wrote these words midway through his reign as king in the city of Nephi. These chapters would have reassured Nephi’s people that, even though they would live in isolation and even though they knew that their posterity would not last, their efforts would not be in vain or unimportant. The Lord would come to them (ch. 26), they would leave a record that would come forth miraculously (ch. 27), and even though the devil would seek in many ways to impede the progress of that book (ch. 28), it will figure prominently in the last days (ch. 29), when many covenant people shall be restored with rejoicing unto the blessings of the Lord (ch. 30). At that point Nephi says, "And now, my beloved brethren, I make an end of my sayings" (30:18). And thus, these chapters should rightly be read as a textual unit.