Darkness and apostasy will cover the earth in the last days—The Book of Mormon will come forth—Three witnesses will testify of the book—The learned man will say he cannot read the sealed book—The Lord will do a marvelous work and a wonder—Compare Isaiah 29. About 559–545 B.C.
This whole chapter is a much more pure source of Isaiah's writing found Isaiah 29, which is plainly written. I love this chapter! It shows that Isaiah also spoke plainly, that man cannot err.