Tenebrae is always held on the Wednesday night before the beginning of the Sacred Triduum: Holy Thursday, Good Friday, and Holy Saturday. The booklet we had tonight so we could follow along had this explanation of what Tenebrae is:
The word Tenebrae comes from the Latin word for "darkness" or "shadows". In another age, monks chanted the ancient psalms and lamentations in the darkness of the night or the very early morning. These early offices (Matins and Lauds) of the Sacred Triduum began to be anticipated the evenings before Thursday and Friday of Holy Week.
A singular feature of this service is the fact that as the service progresses candles are gradually extinguished. Here, in the darkened church, we will extinguish all the lights until only one candle remains.
For a brief time -- for the length of the Lord's Prayer -- we remain in darkness, meditating on the mystery of Christ's death and the apparent victory of the darkness and evil in our lives, only to be startled by a loud noise (strepitus) symbolizing the earthquake at the time of the resurrection. The candle then reappears and by its light we pray and leave quietly, anticipating the events to unfold in the Sacred Triduum.
This is one of my favorite services each year. Despite the ongoing Lamentations of Jeremiah the Prophet throughout and the other kind of depressing aspects, there is plenty of hints of the joyfulness to come and it certainly puts you in the right mood for the next several days before Easter. Also, this is one service that is totally infused with music, another reason why I like it so much.
In our diocese, this service takes place every year with the Bishop at the Cathedral, which is our church. The music is mostly a cappella, some organ, lots of chanting (the Lamentations particularly), and the loud noise symbolizing the earthquake is done with a huge roll on the tympani.
Our regular choir does not do this service. The Cathedral also has a special group (which is audition only) called a schola and this is one of the few services that they do each year. They always do a wonderful job. They lead the congregation in a couple hymns and they do two or more psalms. But they also did a beautiful prelude piece by Michael Haydn called Tenebrae factae sunt and an anthem in honor of Mary (which was done near the end in total darkness) by William Byrd called Ave verum corpus. But my favorite piece, which was done after the homily in semi-darkness was also an anthem, this time by Gregorio Alllegri called Miserere mei. The schola, in the choir loft behind the alter, sang a line, then the person who was doing the chanting would sing the next line all alone from the very front of the alter, near the congregation, then the next line was sung by a small group of women (sopranos and altos) from the very back of the church, so their sound carried over our heads from behind. The various lines of the song kept switching between them all and it was very cool. The chant mixed in with the four-part harmony which was very polyphonic, was quite cool. I kept thinking about writing four-part, medieval style (or Renaissance? not sure when Allegri lived) music for my music theory classes in college while they were singing. But I did listen carefully and it was interesting to try and pick out the various parts while they were singing, the variety was cool too. I also know some of the people in the group and know their singing voices. I could easily pick out the voice of the soprano who is going to be the cantor at my wedding. She was in the group of women at the back of the church. It wasn't because she has a loud voice, well, she does, but she wasn't sticking out in a bad way. Her part was very high and it was often soaring above the other voices who had more movement in their parts. It was very cool!
Overall, this is an interesting service. If you ever get a chance to go to one, I highly recommend it. Not every diocese does it, and remember that if there is one in your diocese it is most likely at the cathedral parish. If you can't find one near you, come join us next year!!