In 1843, Joseph Smith taught, ?If a man gets the fulness of God, he has to get [it] in the same way that Jesus Christ obtain[ed] it & that was by keeping all the ordinances of the house of the Lord.?[1]  Here Smith suggested that Jesus had undergone the same rites that would be performed in the Nauvoo Temple.  Again, Morton Smith and others have argued that Jesus did perform some kind of higher rite and that such continued to be performed, particularly in late second-century Alexandria.  Such a rite likely had elements in common with rites described in Judeo-Christian apocalypses, mysteries (particularly Eleusis), and Platonism, and pieces of the rite may have had echoes in parts of the Catholic liturgy (particularly baptism) and theurgy.  So if Joseph Smith attempted to piece together this lost rite based on all these elements (apocalypses, mysteries, Plato, Catholic rites, and theurgy),[2] he would have been on the right track.

[1] June 11, 1843, Words of Joseph Smith, 212.

[2] A forthcoming dissertation claims that the endowment had these elements.