"Sanctus" by Gregorio Allegri

Gregorio Allegri, who lived from 1582 to 1652, is most well known for his for magnificent 7-voice setting for Psalm 51, his “Miserere”. As it happens, that was just one many beautiful compositions.  His biographical entry on Wikipedia tells us: 

Among Allegri's musical compositions were two volumes of concerti for five voices published in 1618 and 1619; two volumes of motets for six voices published in 1621; an edition of a four-part sinfonia; five masses; two settings of the Lamentations of Jeremiah; and numerous motets which were not published in his lifetime. He was one of the earliest composers for stringed instruments, and Athanasius Kircher has given one specimen of this class of his works in his Musurgia. Most of Allegri's published music, especially the instrumental music, is in the progressive early Baroque concertato style. However, his work for the Sistine Chapel is descended from the Palestrina style, and in some cases strips even this refined, simple style of all ornament. He is credited with the earliest string quartet.

As the beautiful “Sanctus” above makes clear, Allegri has more than one jewel in his treasury.