A recent post on the Abbey of Rievaulx by Zephyrinus concludes with an "organum" setting of the "farced" Kyrie Orbis Factor. Such settings were often named for the opening lines of their "farcing." For instance, "Orbis Factor, Rex Aeterne, eleison! Kyrie eleison!" ("Maker of the world, Eternal King, have mercy! Lord, have mercy!") While searching for other farced settings I came across Christopher Tye's quasi-polyphonic version of the Orbis Factor. The music is an interesting and pleasing blend medieval piety with a controlled, moderated polyphony. Have a listen.