First Nephi 14:18-27
More than 600 years before the apostle John wrote the book of Revelation, Nephi saw him, and what we would write about. Nephi wasn't the only one to see the things that he saw in his vision. But he was only allowed to write a "small part" of the things that he saw (v.28). Others have seen them as well, and written them (v.26). But their accounts are not available to us, they are sealed up for now. The only surviving account we have a copy of is that of the apostle John as he wrote it in the book of Revelation in the Bible. But this account might still remain fragmentary and lacking it's original clarity after his words were sifted and changed by unholy people (13:26). Note how the angel says when they were written, they "were plain and pure, and most precious and easy to the understanding of all men". This sounds like what Nephi wrote in the four previous chapters (11-14) - plain, pure, precious, easy to understand. But it doesn't sound like what "all men" would say concerning our present day Book of Revelation. Maybe the plain and precious parts haven't been restored yet so that we can use faith, prayer, work, and personal revelation to demonstrate to God our desire to understand, which demonstration will earn those most precious things.