CAPPELLA, COMPOSIZIONE a. — During the period of the greatest splendour of polyphonic music, when the most important centres of musical life were the chapels and the most celebrated composers were precisely their singers or directors (maestri), the term “composition a c.” generically designated all ecclesiastical compositions in the polyphonic style, whose performance was entrusted to choirs not supported by any instrumental accompaniment.
The term continued to have this meaning even when (at the end of the 15th century) some chapels accepted the innovation of accompanying the sacred offices with the sound of certain instruments, and when, in the 16th and 17th centuries, the importance of organists in the chapels became paramount (A. and G. Gabrieli in the chapel of S. Marco in Venice). In Germany, singing properly a c., which was very widespread in the 15th and 16th centuries, subsequently declined in importance, since the practice there had greatly developed of combining, in religious music, human voices (“solo” or “choir”) with instrumental timbres, especially in the various forms of the so-called concertato.
“Time a c.” (or “alla breve”) is the name given to that type of rhythmic division in which the beats or measures consist of a breve, or four minims; it was widely used in ancient church music, when the unit of measurement was the minim, which appears ordinarily to have had a duration similar in value to our crotchet. In modern usage, time a c. or alla breve may signify a 2/3 time (or even an ordinary 3/3 time beaten more quickly), marked to indicate the division of the measure into 2 minims; or it may still signify a 2/3 time marked C or, more rarely, C/O (from the ancient sign C/O, by which the breve sometimes assumed the value of a unit of measurement corresponding to 3 rather than 2 semibreves).
Anna Maria Gentili