Nephi echoes here his general purpose, originally described in 1 Nephi 9:4. He clarifies his statement, however, with a description of what the scriptures mean to him. They are a personal delight; and as these plates are a personal record of his “ministry,” quotations from the brass plates are fitting. However, he has only once quoted a lengthy passage. Perhaps this comment reflects his intention to laboriously but lovingly copy the extensive quotations from Isaiah that will follow. Or perhaps his large plates may also have contained long quotations from the brass plates.
Despite Nephi’s personal statement (these things “delight” his soul), he also is writing to benefit his future readers. Nephi is conscious of his ultimate audience. He wants these scriptures that mean so much to him to also have the same value to his readers.