Medieval Polyphony: Organum

In organum and this early polyphony composers added additional melodies to existing lines of chant - chant sung unbelievably slowly at times. I'd like to ask you to think about two aspects of this process.
1) How should we understand this act of adding an additional line of music to a sacred chant? Just why were these people writing, or improvising, these additional lines?
2) Where is the role of emotion in this music?
Next time, we'll continue discussing the the role of music in the medieval church, some technical aspects of coordination, as well as these and other questions.