Dr Oliver Rosteck, the vocal ensemble leader of the Studiooper der Universität Bremen, introduced me to In Stillernacht, a 4-part arrangement by Johannes Brahms which can be found in 26 Deutsche Volkslieder - Johannes Brahms.
We sang it under Oliver's direction at the Schönbergiade 02 and Ceilidh 2002 in June 2002 and again during the final Ceilidh 2003 in June 2003. The song itself is hauntingly beautiful song about hearing a mournful voice in the quietness of the night that melted the heart of the listener. It has remained a great favourite of mine and pops into my head during quiet moments.
A solo version is also given in Lieder, Songs und Gospels 2

Lyrics