Joseph Fielding Smith: When everything gets finished, we will all be one family--every member of the Church a member of one family, the family of God. And we will all be subject to our first progenitor, Adam, Michael, the archangel, who has been appointed and given authority under Jesus Christ to stand at the head and preside over all his posterity. We are one family. So it is not merely enough that we be baptized for our dead or for ourselves, but also we have to be sealed to our parents. We must have the parents sealed to their parents and so on, as far back as we can go, and eventually back to Adam.
There will be cases where some of our ancestors will not be worthy and will drop out, but the links will have to be joined without them. So when the Prophet says we cannot be saved or exalted without our dead, he had this in mind. Suppose we do not do any work for our ancestors. Then where are we? We are out on a limb. We leave ourselves on the side lines. We are not joined into this great family. We may be born under the covenant and thus belong to our parents, but where there are breaks in that lineage we are not united.
(Book: "Doctrines of Salvation," vol. 2, pp. 173-174)
