A Dictionary of Music and Musicians/Gradual
GRADUAL (Lat. Graduale; from gradus, a step). A short anthem sung at High Mass, between the Epistle and Gospel for the day.
In the early ages of the Church, the Gradual was chaunted, by the Deacon, from the steps of a primitive species of reading-desk, called the Ambo, or Ἀμβον; from which steps this portion of the Service derives its peculiarly characteristic name. It is now sung by the Choir: the first clause, by two Cantors only; the remainder, in full chorus. On Sundays, and Festivals, it is usually supplemented by the Alleluia and Versus. During the Seasons of Septuagesima, and Lent, and on some few other occasions, these are omitted, and the Gradual, properly so called, is sung alone. On the Sundays after Easter, the Gradual itself is omitted, and the Alleluia, and Versus, are sung alone. Special forms of both are appointed, for daily use throughout the ecclesiastical year. The words are taken, with very few exceptions, from the Book of Psalms: and the Plain Chaunt melodies to which they are invariably sung form part of the volume called the Graduale Romanum, to which the reader must be referred for their general style. Before the 9th century, the Gradual proper was repeated, in full, after the Alleluia, and Versus.
The so-called 'Graduals' of Haydn, Mozart, and some other modern composers, are Graduals in name only; and will be more properly discussed in the article Motet.