Tenebrae (Latin for 'shadows' or 'darkness') is a Christian religious service celebrated on the evening before Good Friday. The distinctive ceremony of Tenebrae is the gradual extinguishing of candles while a series of readings and psalms is chanted or recited. (Paraphrased from Wikipedia)
While performing with ProMusica from Washington Adventist University, we would hold a Tenebrae service every year. It was the one service everyone in ProMusica would look forward to, despite it being the most emotionally and physically draining experiences of the year. The music was deeply moving, and so emotionally charged, by the end of the service we would all be on the brink of tears, hearts swollen with a sea of emotion.
One of the last things I was able to take part in with that group was the recording of some of our Tenebrae music. I listen to it often during the year, but on Maundy Thursday, it carries particular emotional weight.