At this point, Nephi returns to his source in Isaiah. Isaiah 29:11 reads: “And the vision of all is become unto you as the words of a book that is sealed, which men deliver to one that is learned, saying, Read this, I pray thee: and he saith, I cannot; for it is sealed.” Verses 15 through 18 of 2 Nephi 27 begin with Isaiah’s words, but expand upon them. More context is given.
Some of the context here appears to have been supplied from the fulfilled prophecy of Martin Harris’s trip to the learned men in the East. Part of the story, as it has come to be known, has Charles Anthon asking that the book be brought to him. That is not a feature of Isaiah, and its presence here may come for the understanding of how that prophecy was fulfilled. The translation may have been affected by the extra knowledge gained through having seen the fulfillment of the prophecy.
Nephi returns closer to the Isaiah source by noting that the learned man cannot read the sealed book.