The Kanon Pokajanen (Canon of Repentance) is a sacred composition written by famed Estonian composer Arvo Part. The text was written by St. Mathew of Crete who, among many capabilities, was a proficient hymnographer during his lifetime. Arvo Part set the text of the Canon to music in order to commemorate the 750th anniversary of the Cologne Cathedral in Germany. He is one of the greatest composers of sacred music that is presently living, and whose name will surely accompany the names of the best composers of the Renaissance.
Here is Ode I of the Canon of Repentance. You will either like it, or (more than likely) be repulsed by its heavy and sorrowful constitution (focus on the opening salvos from the choir). I, personally, find this piece magnificent and sorrow-stricken (I mean that in a good way- after all, it is a canon of repentance), as well as infused with a palpable sense of mysticism (listen to the choir oscillate between high and low notes at about 1:29). Musical operations of this type make me anxious for Lent and remind me that there is a true Mystery to be experienced.
Eight seconds into the piece the choir starts singing.
Ode l - Arvo Pärt