Sealed book of Mormon Ch.10

AND now, I am constrained by the Spirit to
explain further some of the things that the Lord
suffereth to be given to the children of men that
they might be kept in remembrance of him, that
they might always remember him and keep his
commandments which he hath given unto them,
so that the Holy Ghost may always be with them during the course of the days of their probation.
And many of these things are taught unto
the people symbolically through the
administrations of the Holy Priesthood that
hath been established in the churches that he
hath suffered to be built up among the
children of men.
And many of these things are taught in the
temples of the Lord, as they are called by the
church, and are the basis of an endowment of
great understanding and teaching unto the
children of men.
Behold, the Lord showed this endowment
unto Adam and his posterity and commanded
them to teach their children this sacred
ordinance as a way to keep them in
remembrance of him.
And this endowment was given unto many
of the prophets of God to give unto the people a
symbolic representation of the plan of salvation,
and also to teach them many of the truths that
the Father revealed unto His children in His
kingdom before He placed them in the world
that He had created for them.
And this endowment was given unto Nephi
who passed it down from generation to
generation, and it was taught in the temples that
he caused to be built among his people.
And it was a cause of exceeding joy to the
people of Nephi that they had the opportunity to
go to a temple dedicated to the teachings and
instructions of the Lord.
And at this time, or during the time of the
reign of Nephi, there was none that was
prohibited from partaking of the ordinance of
the endowment, it being taught to the people
symbolically with signs, tokens, penalties, and
symbols that no one could understand unless he
was given this knowledge and understanding by
the gift of the Holy Ghost, which gift was only
given to those who were righteous.
And it was the purpose of Nephi and his
brothers, who were anointed High Priests, to
teach the people the words of Christ, that all
people should be allowed to have the
endowment presented before them, thus with
the hope that they might be encouraged to seek
an understanding of the mysteries of God.