The ordinance of the sacrament has two components: bread and wine (or another liquid). The New Testament model includes both in the last supper scenario (Mark 14:22–24), as well as in early Christian tradition.
The model available for the sacrament in the Book of Mormon was unquestionably a distinctive episode: the Savior’s introduction of the sacramental meal to the Nephites at Bountiful. In contrast to the description on the covenant of the bread (see commentary accompanying Moroni 4), the correspondence is less clear between the 3 Nephi description and the blessing on the wine in Moroni 5:
And it came to pass that when he [Jesus] said these words, he commanded his disciples that they should take of the wine of the cup and drink of it, and that they should also give unto the multitude that they might drink of it.
And it came to pass that they did so, and did drink of it and were filled; and they gave unto the multitude, and they did drink, and they were filled.
And when the disciples had done this, Jesus said unto them: Blessed are ye for this thing which ye have done, for this is fulfilling my commandments, and this doth witness unto the Father that ye are willing to do that which I have commanded you. (3 Ne. 18:8–10)
Mormon’s description includes the covenant of obeying the commandments, which is explicit in the blessing on the bread but only implied by “do always remember him” in the blessing on the wine. The similarities and dissimilarities between the records in 3 Nephi and Moroni 5 suggest that, while the language in Moroni is fixed, it was not necessarily the repetition of a fixed phrase in the original plates. Mormon and Moroni wrote some four hundred years after the Nephite practice. Both were familiar with the sacrament prayers as Moroni records them. Therefore, the similarities in language between the blessing on the bread and the 3 Nephi account have an equal chance of being influenced from Mormon and/or Moroni’s familiarity with the current fixed-language practice as that 3 Nephi was the source for the fixed-language.
The evidence of the sacrament as a liturgical form in Old World Christianity also shows development of the rite. While the model is certainly the Last Supper, there is only a tenuous relationship between developed Christian practice and the context of a Passover meal in which the Savior instituted it. Later Christian practice became disassociated from the Passover, even though the symbolism of the paschal lamb and Christ as the sacrifice for humankind remained. As one detail, the sacrament occurred much more frequently than the Passover, which was only an annual event.
The Book of Mormon probably represents a similar development from feeding a multitude to partaking of ritual emblems. Before Jesus explained the symbolism of the sacrament, the multitude ate and drank until their hunger and thirst were satisfied:
And it came to pass that Jesus commanded his disciples that they should bring forth some bread and wine unto him.
And while they were gone for bread and wine, he commanded the multitude that they should sit themselves down upon the earth.
And when the disciples had come with bread and wine, he took of the bread and brake and blessed it; and he gave unto the disciples and commanded that they should eat.
And when they had eaten and were filled, he commanded that they should give unto the multitude.
And when the multitude had eaten and were filled, he said unto the disciples: Behold there shall one be ordained among you, and to him will I give power that he shall break bread and bless it and give it unto the people of my church, unto all those who shall believe and be baptized in my name.
And this shall ye always observe to do, even as I have done, even as I have broken bread and blessed it and given it unto you. (3 Ne. 18:1–6)
The fact that the Messiah originally fed the Nephites a meal seems to parallel the early Christian agape feast which accompanied the presentation of the sacrament. Then he explained the symbolism of the sacrament and codified the symbols separately from the meal. This step, I argue, is represented by the fixed-form prayers in Moroni but which are not recorded in 3 Nephi.