A Dictionary of Music and Musicians/Missa de Angelis
MISSA DE ANGELIS. The name generally given to a very beautiful Plain-Chaunt Mass, in Mode XIII, prescribed in the Ratisbon Gradual, for use 'In Festis Solemnibus,' and appended to the Mechlin Gradual, as a 'Missa ad libitum.' Judging from the internal evidence afforded by the freedom of its phrasing, and the Mode in which it is written, the Missa de Angelis would seem to be by no means the oldest Mass of this class now in use: its antiquity is, however, great enough to have obliterated all trace of its history, and even of the origin of the name by which it is now generally designated, and under which it is perhaps more frequently sung than any other Mass of its kind, both in its original form, and in the English translation used at S. Alban's, Holborn, S. Mary's, Paddington, and other London Churches in which Gregorian Services are encouraged.
The number of the older Masses to which allusion has been made is very small. The Ordinarium Missse in the Ratisbon Gradual, published under the authority of the Congregation of Rites, contains: the 'Missa in Tempore Paschali' in Modes VII and VIII; a very fine 'Missa in Duplicibus,' beginning in Mode I, and another in Mode VIII; a 'Missa Beatæ Marias' beginning in Mode I, and another in Mode VIII; the 'Missa in Dominicis,' in Mode I and II; the 'Missæ in Festis Semiduplicibus' and 'In Festis Simplicibus,' both begining in Mode VIII; the well-known 'Missa pro Defunctis,' beginning in Mode I, and including the famous 'Dies iræ' in Modes I and II; and some smaller Masses, sung in Advent, and Lent, during Octaves, and on Ferial Days. The Mechlin Gradual also gives another 'Missa ad libitum' in Mode XIII, and yet another in Modes VII and VIII.
Some editions of the Paris Gradual add to these a spurious 'Missa Regia,' professedly in Mode I, but really in the modern key of D minor, composed by Dumont, Maître de Chapelle to Louis XIV, in acknowledged imitation of the older unisonous Masses, but in utter ignorance of the principles upon which they are constructed, and without a trace of appreciation of their true style or sentiment. This Mass was once very popular in France, and much sung in the Paris Churches; but since the revival of the taste for pure Ecclesiastical Music, it has wisely been discarded in favour of the older Masses which it was intended to displace.