The Doctrine and Covenants/Section 131

Instructions given by Joseph Smith, Ramus, Illinois, May 16 and 17, 1843. History of the Church 5:392-93.

the celestial glory there are three heavens or degrees;

And in order to obtain the highest, a man must enter into this order of the priesthood [meaning the new and everlasting covenant of marriage];

And if he does not, he cannot obtain it.

He may enter into the other, but that is the end of his kingdom; he cannot have an increase.

(May 17th, 1843.) The more sure word of prophecy means a man's knowing that he is sealed up unto eternal life, by revelation and the spirit of prophecy, through the power of the Holy Priesthood.

It is impossible for a man to be saved in ignorance.

There is no such thing as immaterial matter. All spirit is matter, but it is more fine or pure, and can only be discerned by purer eyes;

We cannot see it; but when our bodies are purified we shall see that it is all matter.