The glorious vision of the brother of Jared was recorded by him and sealed up. It becomes the infamous sealed portion of the Book of Mormon, destined to come forth only when the world is sufficiently righteous (this probably means after the start of the Millenium). Nephi wrote of this sealed portion, saying:
’behold the book shall be sealed; and in the book shall be a revelation from God, from the beginning of the world to the ending thereof.
Wherefore, because of the things which are sealed up, the things which are sealed shall not be delivered in the day of the wickedness and abominations of the people. Wherefore the book shall be kept from them.
…And the day cometh that the words of the book which were sealed shall be read upon the house tops; and they shall be read by the power of Christ; and all things shall be revealed unto the children of men which ever have been among the children of men, and which ever will be even unto the end of the earth.’ (2 Nephi 27:7-11)
Joseph Fielding Smith
“At the command of the Lord…Moroni also sealed up the greater things in this vision and also the interpreters-which were the same ‘two stones’ had by the Brother of Jared-so that this vision should not be made known even in our day among the Gentiles, in the day of their wickedness; it could not be revealed ’until the day that they shall repent of their iniquity, and become clean before the Lord.’ (Ether 4:6) So we today do not have the fulness of the account written and sealed up by the Brother of Jared and again sealed by Moroni. This part of the record the Prophet Joseph Smith was forbidden to translate. We have, then, received but the ’lesser part.’” (Doctrines of Salvation, 3:224-5)
Joseph Fielding Smith
“Now the Lord has placed us on probation as members of the Church. He has given us the Book of Mormon, which is the lesser part, to build up our faith through our obedience to the counsels which it contains, and when we ourselves, members of the Church, are willing to keep the commandments as they have been given to us and show our faith as the Nephites did for a short period of time, then the Lord is ready to bring forth the other record and give it to us, but we are not ready now to receive it. Why? Because we have not lived up to the requirements in this probationary state in the reading of the record which had been given to us and in the following its counsels.” (Conference Report, Oct. 1961, p. 20)