Coolest. Incipit. Ever!
Advent will soon be upon us, which means many things, among which is the annual fight--a polite one, no doubt--over who gets to sing the incipit (opening phrase) to the solemn version of Alma Redemptoris Mater.
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The Original Post on NLM has a splendid version of the solemn tone sung to Ambrosian Chant.