Apostle Joseph F. Smith preaches from the Tabernacle pulpit: "Some people have supposed that the doctrine of plural marriage was a sort of superfluity, or non-essential to the salvation or exaltation of mankind. In other words, some of the Saints have said, and believe, that a man with one wife, sealed to him by the authority of the Priesthood for time and eternity, will receive an exaltation as great and glorious, if he is faithful, as he possibly could with more than one. I want here to enter my solemn protest against this idea, for I know it is false. . . . Therefore, whoever has imagined that he could obtain the fullness of the blessings pertaining to this celestial law, by complying with only a portion of its conditions, has deceived himself. He cannot do it."
[Source: Journal of Discourses, Vol.20, p.31, Joseph F. Smith]