One of the major problems of being random is that I sometimes move on to other topics which I have in my head before fully covering a given topic. For instance, I mentioned Candlemas without mentioning Guillaume de Machaut's Messe de Notre Dame. That's the equivalent of discussing the history of beer without mentioning Budweiser or Coors or MGD. Anyway, I mention this for a couple of reasons. First, Machaut's mass is the earliest polyphonic mass we know of, so it is extremely important in the history of Western music in general and sacred music in particular. Second, this mass was written to be used on the four Marian feast days (Nativity of the Virgin (Sept. 8), Purification a.k.a. Candlemas (Feb. 2), Annunciation (March 25), and Assumption (Aug. 15)). On the specific recording I have, the propers are for the Candlemas. Finally, I need to mention it because it is a gorgeous piece of music. Polyphonic chant is one of the most beautiful things one can listen to while meditating, reading, praying, etc. The music is extremely relaxing, and it contains that aura of transcendence that communicates the loving, great, powerful God we believe in. I own the Harmoni Mundi recording of the mass, which can be quite disconcerting the first time you listen to it. I am sure amazon.com has many different recordings of this masterpiece. Check it out if you want to hear something simple, yet complicated.