Fermentum, Commixture and the Politics of a Fragment

A broken fragment turned out to be useful for saying something that was hard to say any other way. In Rome the bishop could not preside at every eucharist in a city of many congregations, so a particle of the bread consecrated at his own liturgy was carried to the presbyters serving the other churches and put into their chalices. The custom is called the fermentum, and it is attested in a letter of Pope Innocent I in the early fifth century. It is a piece of church order performed with bread: the presbyter's eucharist is not a separate eucharist, and the fragment in his cup says so without anyone having to argue it.

The commixture is a different practice with a similar economy of means. Putting a particle of the consecrated bread into the chalice is common to the eastern and western rites, and it has been explained in several ways. The most widespread reading is that the separation of the body and the blood on the paten and in the cup represents the death, and their reunion in the chalice the resurrection. Other explanations have been offered in both traditions, and the gesture is older than any of the explanations attached to it, which is a common pattern in liturgy and a reason for treating the standard account as a reading rather than an origin.

The Byzantine fraction carries its own vocabulary. The four parts of the Lamb are named from the letters stamped on the loaf, the portion marked with the abbreviation of Jesus goes into the chalice, and the remaining parts are broken up for the communicants and for the reserved sacrament kept for the sick.