their place being supplied by a Tractus, with one or more Versus attached to it, the music of which corresponds exactly, in style, with that of the Gradual and Versus already described.
On the Festivals of Easter, Pentecost, Corpus Christi, and the Seven Dolours of our Lady, and also at Masses for the Dead, the Gradual is followed by the Sequentia, or Prosa—a species of Hymn of which a great many examples were once in existence, though five only now remain in use. These five are the well-known 'Victimæ Paschali,' 'Veni Sancte Spiritus,' 'Lauda Sion,' Stabat Mater,' and 'Dies iræ'—a series of Hymns which, whether we regard their quaint mediæval versification, or the Music to which it is adapted, may safely be classed among the most beautiful that ever were written. [See Prosa; Sequentia.] Compared with the Melodies we have been considering, those of the Sequences are of very modern origin indeed. The tuneful rhymes of 'Veni Sancte Spiritus'—known among mediaeval writers as the 'Golden Sequence'—were composed by King Robert II of France, about the year 1000. 'Victimiæ Paschali' is probably of somewhat later date. The 'Dies iræ' was written about the year 1150, by Thomas of Celano, while the 'Lauda Sion' of S. Thomas Aquinas can scarcely have been produced before the year 1260. In all these cases, the Plain Song Melody was undoubtedly coæval with the Poetry, if not composed by the same author; and we are not surprised to find it differing, in more than one particular, from the Hymns collected by S. Ambrose and S. Gregory. Four out of the five examples now in use are in mixed Modes; and, in every instance, the Melody exhibits a symmetry of construction which distinguishes it alike from the Antiphon and the Hymn. From the former, it differs in the regularity of its rhythm, and the constant repetition of its several phrases; from the latter, in the alternation of these phrases with one another; for, while the Verses of the Hymn are all sung to the same Melody, those of the Sequences are adapted to two or more distinct Strains, which are frequently interchanged with each other, almost after the manner of a Rondo, a peculiarity which is also observable in some very fine, though now disused Sequences, which were removed from the Missal on its final revision by the Council of Trent.
The style of the Offertorium differs but little from that of the Gradual, though it is sometimes a little more ornate, and makes a more frequent use of the Perielesis. Like the Gradual, it is sometimes—as in the 'Missa pro Defunctis'—followed by a Versus; but it more frequently consists of a single member only, without break or repetition of any kind. In Paschal Tide, however, it is followed by a proper Alleluia in its own Mode. [See Offertorium; Perielesis.]
The last portion of the 'Proprium Missæ' for which a Plain Song Melody is provided in the Office-Books is the Communio. This is usually much shorter than either the Gradual or the Offertory; from which it differs in style so slightly as to need no separate description. It is followed, in Paschal Tide, by a proper Alleluia, which, of course, conforms to its own proper Mode.
The 'Ordinarium Missæ'—i.e. that part of the Mass which is the same on all occasions—is preceded, on Sundays, by the Asperges, which exactly resembles the Introit, both in the arrangement of its words, and the style of its Music an extremely beautiful instance of the use of the Seventh Mode.
Of the Kyrie, Gloria, Sanctus, Benedictus, and Agnus Dei, the Ratisbon Gradual gives ten Plain Song versions, in different Modes, and adapted to Festivals of different degrees of solemnity; besides three Ferial Masses, in which the 'Gloria' is not sung, and the beautiful 'Missa pro Defunctis.' The Mechlin Gradual gives eight forms only for Festivals, and one for Ferial Days. Of the Credo, four versions are given, in each volume. It is impossible even to guess at the date of these fine old Melodies, some of which are exceedingly complicated in structure, while others are comparatively simple. The shorter movements, such as the Kyrie and Sanctus, are sometimes very highly elaborated, with constant use of the Perielesis, even on two or more consecutive syllables; while the Gloria and Credo are developed from a few simple phrases, frequently repeated, and arranged in a form no less symmetrical than that we have described as peculiar to the Sequence, though the alternation of strains, which serves as the distinguishing characteristic of that form of Melody, is carried out in a somewhat different way.
The oldest known copy of the Sursum Corda and Prefaces dates from the year 1075. The style of these differs very materially from that of the other portions of the Mass, and, like that of the Pater Noster, is distinguished by a grave dignity peculiarly its own. In addition to these, the repertoire is enriched by certain proper Melodies which are heard once only during the course of the Church's Year; such as the Ecce lignum Crucis and Improperia, appointed for Good Friday; and more especially, the Exultet, sung during the blessing of the Paschal Candle on Holy Saturday. This truly great composition is universally acknowledged to be the finest specimen of Plain Song we possess. It is written in the Tenth, or Hypoæolian Mode; and is of so great length, that few Ecclesiastics, save those attached to the Pontifical Chapel, are able to sing it, throughout, without a change of pitch fatal to the perfection of its effect; yet, though it is developed, like the 'Credo,' and some other Melodies we have noticed, from a few simple phrases, often repeated, and woven, with due attention to the expression of the words, into a continuous whole, the last thought one entertains, during its performance, is that of monotony or weariness. The first phrase, which we here transcribe, will perhaps suffice to give the reader a good idea of the general effect of the whole.
