AGOSTINO AGAZZARI. — Musician, born in Siena on 2 Dec. 1578, died there on 10 Apr. 1640. He served as maestro di cappella, first at the Collegio Germanico in Rome from 1608 to 1630, then at the Siena cathedral from 1630 until his death. He played a major role in spreading the use of thoroughbass (basso continuo), of which, together with Adriano Banchieri, Orazio Tarditi (Bianciardi), and Ludovico Grossi da Viadana, he was one of the earliest advocates. He laid the foundations for this practice in a fundamental theoretical work that is also regarded as the first true treatise on instrumentation: *Del sonare sopra’l basso con tutti li stromenti e dell’uso loro nel conserto* (Siena 1607).
Another of his theoretical works on sacred music in conformity with the Council of Trent is *La musica ecclesiastica*, which contains the true principles of music as a science: no longer viewed merely in terms of its nobility (Siena 1638). As a composer, he left a vast output of sacred music, including four books of *Sacrae Cantiones* for 2 to 8 voices (1602–1606), various collections of Psalms (1609, 1610, 1611, 1612), four Masses (for 4, 5, and 8 voices, Venice 1617), *Stille soavi di celeste aurora* for 3, 4, and 5 voices with thoroughbass (Venice 1602), *Eucharisticum melos* (Rome 1625), *Litanie della B. V. M.* (Rome 1639), and others. Some of his compositions have appeared in modern editions in *Musica Divina* by Proske (IV: *Stabat Mater*), and a facsimile of the 1607 treatise was published by the *Bollettino Bibliografico Musicale* of Milan.