For those folks out there who aren't familiar with the traditional Latin Catholic Mass, the parts of the mass that are typically sung (Kyrie, Gloria, Sanctus and Benidictus, Angus Dei) have different music for different events.
For those who don't feel like looking up the translations of those parts, they are:
Lord Have Mercy (typically spoken, not sung, even in Novus Ordo masses)
Glory to God
Holy, Holy, Holy
Lamb of God
Keep in mind that church songs are simply prayers put to music. The parts of the Traditional Mass have been sung and re-sung for centuries; it only makes sense that at some point, some priest or monk would say "Hey, why don't we change it up a little bit?" The Missa de Angelis is the typical mass that most people learn, and I've been able to find it just about everywhere. The Orbis Factor mass is supposed to be sung during normal times in the liturgical calendar, when there isn't a specific season that we're celebrating. It's one of the oldest masses the Church as sung, and it sounds like it - very Byzantine. And Cum Jubilo is used for masses honoring the Blessed Virgin. This is what I'm practicing right now
It's a bear to learn, and I've got to have it down pat by February 2nd. Yay me. Here's just the Kyrie:
I suppose if I'd been able to focus on this, it wouldn't be such a big deal, but this week has been a kick in the balls. Grrrrrr.....
Ah well, off to learn some more music.