Note 1 — M. CAMILLE SAINT-SAËNS

Plain Song (Fr. Plain Chant) was the earliest form of Christian church music. As its name indicates, it was a plain, artless chant without rhythm, accent, modulation or accompaniment, and was first sung in unison. Oriental or Grecian in origin, it had four keys called Authentic Modes, to which were added later four more called Plagal Modes. These modes, called Phrygian, Dorian, Lydian, etc., are merely different presentations in the regular order of the notes of the C Major scale—first, with D as the initial or tonic note, then with E et seq. They lack the sentiment of a leading seventh note. In these weird keys Plain Song was conceived for psalms, graduals, introits, and other offices of the primitive church. Such music was generally called Gregorian, because St. Gregory, Pope of Rome in the seventh century, collected and codified it, adding thereto his own contributions. Two centuries previous it was known as Ambrosian music, after St. Ambrose, Bishop of Milan.