ORCHESTRA IN LITURGICAL MUSIC. - The Church was always opposed to the use of musical instruments during the sacred rites, notwithstanding that in the early Middle Ages a rather bizarre symbolism attributed to instruments and their various parts subtle correspondences with the spiritual world, whereby in the seven strings of the cithara the virtues vibrate, the trumpet represents the Fourth Gospel, the skin of the timbrel is mortal flesh, and the ten-stringed psaltery prefigures the Ten Commandments. St. Thomas Aquinas declares (Sum. Theol., 2, 2, q. 91) that instruments contribute more to distracting the soul than to concentrating it.
The conspicuous exception made for the organ is perfectly motivated, on one side by the character of the instrument and on the other by the restrictions imposed on its practical use (v. ORGANO). The motu proprio of Pius X on sacred music (22 Nov. 1903) leaves a door open to instrumental ensembles: "In some particular case, in the due terms and with the appropriate regards, other instruments may also be admitted, but not without special license of the Ordinary"; and they must, like the organ, serve the chant: "simply sustain it and never oppress it" (§§ 15-16). In § 19 it prohibits the use of the piano and of the drum kit, and in § 20 it concedes: "only in some special case, given the consent of the Ordinary, will a limited choice of wind instruments be permitted, judicious and proportionate to the setting, provided that the composition and the accompaniment to be performed is written in a grave style, suitable and in all things similar to that of the organ." These directives were necessary as a condemnation of practices handed down from the 18th century, since it is not "the chant with instrumental accompaniment, but the living voice that must resound in the temple; the voice of the clergy, of the singers, of the people" (apostolic constitution Divini cultus, of Pius XI, 20 Dec. 1928; AAS, 21 [1929], p. 33 ff.). In deference to this principle, even today in the papal chapels the choral chant is never accompanied by instruments, indeed not even by the organ.
From all this it is easy to infer that the orchestra in the full sense of the term, as a large ensemble, is without question excluded from participation in the divine service. On the other hand, ensembles of strings or of winds, and therefore also mixed ones, may be associated with the liturgy, without excluding the harp, and string ensembles may be combined with the organ, provided always that they remain within the limits of time and the loftiness of style required by the dignity and spirituality of sacred art.
Edoardo Carducci Agostini