A simple round from the Red Book of Montserrat.
The wikipedia page is a pretty good place to start for more information on this manuscript - look for the Llibre Vermell de Montserrat. There is a facsimile here.
I like the way they manage the round in this recording. It has become our local custom to arrange things similarly, but in a slightly more contracted format.
First line: laudemus virginem mater est, et eius filius Jhesus est (then pause for a bar)
Second line: plangamus scelera acriter, sperantes in Jhesum iugiter (then pause for a bar)
- Sing the first line once in unison. Pause for a bar.
- Sing the whole thing as a canon, in three parts, pausing for one bar between lines. We sing the first line, then the second, then the first line again. Then pause for a bar.
- Sing the first line unison again, quietly.
Each line begins quietly, gets louder through the first phrase, then quieter again through the second phrase.
So Laudemus virginem mater est starts quietly and gets louder; then et eius filius Jhesus est starts loudly and gets quieter.
Cililia has midis online here. (Note that these do not have the pauses used in the version above).
Here is sheet music, arranged as I'd like us to sing it (see below - this is now a little out of date). Note that we sometimes sing it rather lower: starting on B-flat rather than F.
A seventh, at any pitch.