Listen to Sacrum Mysterium: Part I "A Light in the Darkness", Duan Nollaig online. Sacrum Mysterium: Part I "A Light in the Darkness", Duan Nollaig is an English language song and is sung by Apollo's Fire, Meredith Hall, Ensemble La Nef and Sylvain Bergeron. Sacrum Mysterium: Part I "A Light in the Darkness", Duan Nollaig, from the album Sacrum Mysterium (A Celtic Christmas Vespers), was released in the year 2012. The duration of the song is 1:47. Download English songs online from JioSaavn.