Machine translation of the 1948–1954 Italian original. The original text is authoritative.
ISAACK (IZAC), HEINRICH. - Flemish composer, b. ca. 1450, d. in Florence in 1517. He first lived at the court of Ferrara, then became organist and maestro di cappella at S. Giovanni and at the court of Lorenzo the Magnificent in Florence (1480–92), where he was called Enrico il Tedesco.
He is found for a few years in Innsbruck, then again in Florence, later in Augsburg, and from 1497 at the court of Maximilian in Vienna. In 1514 he returned to Florence. Ten masses were printed in Venice in 1506 under the title Missae Henrici Izaac; another collection of 13 masses appeared there in 1539.
Motets, psalms, and hymns are included in collections by Petrejus (Venice 1539) and Rhaw (Nuremberg 1541); many other compositions are found in contemporary and later collections. Isaac’s music, of a highly sustained contrapuntal and polyphonic style, enjoyed wide dissemination in his time.
Bibl.: P. Wagner, Geschichte der Messe, Regensburg 1914, pp. 282–317; H. Rietsch, H. I. und das Innsbrucklied, in Jahrbuch Peters, Leipzig 1917; M. Bakolzer, Studies in mediaeval and renaissance music, New York 1950, pp. 191 and 196.
