without our dead

Joseph Fielding Smith: Now, some members of the Church have wondered just what was meant by the words of the Prophet, that we without our dead could not be made perfect. Will not a man who keeps the commandments of the Lord, who is faithful and true so far as he himself is concerned, receive perfection? Yes, provided his worthy dead also receive the same privileges, because there must be a family organization, a family unit, and each generation must be linked to the chain that goes before in order to bring perfection in family organization. Thus eventually we will be one large family with Adam at the head, Michael, the archangel, presiding over his posterity.

(Book: "Doctrines of Salvation," vol. 2, p. 174)