But the whole subject of the marriage relation is not in my reach, nor in any other man’s reach on this earth. It is without beginning of days or end of years; it is a hard matter to reach. We can tell some things with regard to it; it lays the foundation for worlds, for angels, and for the Gods; for intelligent beings to be crowned with glory, immortality, and eternal lives. In fact, it is the thread which runs form the beginning to the end of the holy Gospel of Salvation–of the Gospel of the Son of God; it is from eternity to eternity. 12#:
Let every man in the land over eighteen years of age take a wife, and them go to work with your hands and cultivate the earth, or labor at some mechanical business, or some honest trade to provide an honest living for yourselves and those who depend upon you for their subsistence; observing temperance, and loving truth and virtue; then would the woman be cared for, be nourished, honored and blest, becoming honorable mothers of a race of men and women farther advanced in physical and mental perfection than their fathers. This would create a revolution in our country, and would produce results that would be of incalculable good. 23#:
This is the reason why the doctrine of plurality of wives was revealed, that the noble spirits which are waiting for tabernacles might be brought forth. 34:56.
Joseph F. SmithMarriage is also a principle or ordinance of the gospel, most vital to the happiness of mankind, however unimportant it may seem, or lightly regarded by many. There is no superfluous or unnecessary principle in the plan of life, but there is no principle of greater importance or more essential to the happiness of man—not only here, but especially hereafter, than that of marriage. Yet all are necessary. What good would it be to one to be baptized and receive not the Holy Ghost? And suppose he went a little further and received the Holy Ghost, thereby obtaining the testimony of Jesus, and then stopped at that, what good would it do him? None whatever, but would add to his condemnation, for it would be as burying his talent in the earth. To secure the fulness of the blessings we must receive the fulness of the gospel. Yet men will be judged and rewarded according to their works. “To him that knoweth to do good and doeth it not, to him it is sin.” Those who receive a part of the gospel with light and knowledge to comprehend other principles, and yet do not obey them, will come under this law; hence, condemnation will be added unto such, and that which they did receive may be taken from them and added to those who are more worthy. 
- ↑ Joseph F. Smith, Gospel Doctrine: Selections from the Sermons and Writings of Joseph F. Smith, compiled by John A. Widtsoe [Salt Lake City: Deseret Book Co., 1939], p. 105
- Brigham Young, Discourses of Brigham Young, p. 195; Journal of Discourses 2:90
- Brigham Young, Discourses of Brigham Young, p. 195; Journal of Discourses 12:194-195
- Brigham Young, Discourses of Brigham Young, selected and arranged by John A. Widtsoe [Salt Lake City: Deseret Book Co., 1954], p. 197; Journal of Discourses 4:56