At the chapel I’ve started attending recently, the priests will use a host broken in half, and they also appear to break off the top “corner” of it.
The Host is broken during the Fraction Rite. It is broken for a number of reasons. Jesus broke the Eucharistic bread at the Last Supper, and so the Eucharistic bread in all Catholic liturgies (not just the Roman Rite) is somehow broken or “fractioned” before Communion. (The fractioning of the Eucharistic bread in the Byzantine Rite is very complex compared to how it is done in the Roman Rite.) The ancient liturgical practice was that a single piece of bread was consecrated, and thus it would need to be divided in order to distribute it to the faithful. (This is less evident in the Roman Rite, where there tends to be many hosts consecrated, not just one.) But as is the case with virtually every facet of the liturgy, a functional act like the Fraction soon acquired a wealth of symbolic meanings.
The earliest meaning had to do with the unity of the faithful in the one mystical Body of Christ, as St. Paul taught the Corinthians: “Because there is one bread, we who are many are one body, for we all partake of the one bread.” (1 Cor. 10:17; cf. GIRM 83) Around the end of the fourth century, Theodore of Mopsuestia (modern Turkey) interpreted the fraction as pertaining to the multiple appearances of the Lord after His Resurrection. (Jungmann, The Mass, p. 207) Eventually, the breaking of the Host came to represent the violence of Christ’s Passion and death, the “bruising” of the Suffering Servant, the chastisement that makes us whole. (cf. Isa. 53:5; Summa Theologiae III, 83, 5) St. John Chrysostom explained that “what He suffered not on the cross, this He suffers in the oblation for your sake, and submits to be broken, that He may fill all men.” (Homily on First Corinthians XXIV)
The gesture also has to do with the Eucharist as spiritual food, for it is by the “breaking of the bread” that it is prepared for distribution to the faithful. And finally, it is related to the Eucharist as the sacrament of peace, because the phrase “to break bread” implies that there is a peace between people.
The small portion which is “missing” from the Host you see the priest holding has been dropp into the Chalice and mixed with the consecrated wine in the “commingling” rite which happens immediately after the Fraction. That too is rich with symbolism (which I could go into if you’d like).
After the bread is broken and the gifts are consecrated, priests will elevate the chalice, holding a host over it. …] On a few rare occassions, I’ve seen the priest hold up an unbroken host. …] is it a mistake for the priest to use an unbroken host?
I
think the GIRM implies that the Host which the priest holds up when he says
Ecce Agnus Dei… (“This is the Lamb of God…”) is the same Host which he just broke during the Fraction Rite:
155.
The priest then takes the host and breaks it over the paten. …]
- Postea sacerdos accipit hostiam, eamque super patenam frangit …]
- When the prayer is concluded, the priest genuflects, takes the host consecrated in the same Mass, and, holding it slightly raised above the paten or above the chalice, while facing the people, says, Ecce Agnus Dei (This is the Lamb of God). …]
- Oratione conclusa, sacerdos genuflectit, accipit hostiam, eamque aliquantulum elevatam super patenam vel super calicem tenens, versus ad populum, dicit: Ecce Agnus Dei …]
Now, the Latin does not say “a host” or “the host” – Latin has no articles, so it simply says “host” (hostiam). But I got the strong sense that the priest is to take the Host he has just broken and replaced onto the paten, and hold that Host up.
In the Extraordinary Form of the Mass (the “Traditional Latin Mass”), the priest holds the principal Host, the one he has just broken. I cannot think of a good reason that would necessitate holding up an unbroken Host.