Alexander Markus Schweitzer is a theologian who, since the mid-1980s, has specialized in Gregorian chant. He completed the AISCGre (International Society for the Study of Gregorian Chant) courses in Gregorian chant in Cremona, studied musicology at the Pontifical Institute for Sacred Music, Rome and Gregorian semiology with J. B. Göschl in Munich. From 1987 to 1989 he was choir-director of the Schola Anselmiana in Rome, from 1989 to 1994 co-director of the Choralschola St. Ottilien, and in 1995 he founded…