Musicians, there is a song that begins Mass that is set to the first reading. It is the announcement that begins the liturgy. We sing the very words of the first reading. It is not a new song but one that dates from the early years of Christianity, and its shape and style show why it has sustained its transforming power to the present day. You can find it in the Graduale, the choir's songbook for the Roman Rite. It is also found in the Gregorian Missal. It is the Gregorian chant for the Introit.
Sometimes when we write about chant, we focus on style and solemnity and history. But here is a more fundamental reason for the chant: it is the music that matches the text of the Mass. If you do not sing the chant, you are leaving out an important part of the aesthetic furnishings for Mass. Anything else is second best: a derivative product at best. At worst, and this is most common, the hymn you sang to begin Mass was just a song of some sort, a song that welcomes us to the space and to each other, but doesn't actually tell us anything about what is going to happen that day.
With the Gregorian song, the first note suggests a longing followed by an excited invitation to come to the water, which is offered by the Lord (Dominus employs the three-note episema symbolizing the Trinity). And you sense the forward motion here, as we do in the Introit generally. We are not merely "gathering"; nor are we singing a "gathering song." We are moving in procession as led by the celebrant to the Lord.
The phrase after the full bar turns out to be a musical elaboration on the first phrase, one that extends the invitation from those who are thirsty to even those who desire drink but have nothing of value to offer in exchange. The water is a free gift offered to all.
Twice does this chant does on this chant touch the note on the first line, the Fa, the lowest note in the range of this piece, as if to suggest the act of lowering our heads in grateful humility to the drink. So it is that the first time is on water. The second time is on drink. Both employ the same melodic figure. And we drink with gladness.
And why? Listen to the music. The phrase on cum laetitia is precisely the same as the melody that ended the first phrase: says the Lord. So in this one small song, which is followed by a Psalm and the Gloria Patri and the antiphon again, we discover the possibility of being joyfully nourished by our Lord. Here is a theme for the reading and a hint as to the whole undertaking of the liturgy. And all of this happens even before the first words are spoken at the Mass.
Here is our preparation for the most wonderful hour of the week.
