Isaac, Heinrich (Henricus) (c. 1450–1517)

Flemish composer. He was a prolific composer of songs and instrumental music, and wrote a Choralis Constantinus consisting of 58 offices for the whole year, but he is popularly remembered for the song ‘Innsbruck ich muss dich lassen’, later harmonized by Johann Sebastian Bach. His wide travel is reflected in the various national influences in his music. He was a major contemporary of Josquin Desprez, Jacob Obrecht, and Pierre de La Rue.

Isaac was born in Brabant. In about 1484, when he seems to have been in Innsbruck, Switzerland, and in touch with Paul Hofhaimer there, he went via Ferrara to Florence, Italy, as musician to the Medici family. He sang in the choir at the Chapel of San Giovanni at Florence, and was regularly employed at the cathedral from 1485. He visited Rome in 1489, and married Bartolomea Bello, the daughter of a wealthy butcher.

Lorenzo de' Medici died in 1492 and subsequently Isaac accepted an invitation from the emperor Maximilian, who visited Pisa in 1496, to join the imperial court, just then about to be transferred from Augsburg to Vienna. He seems to have visited Innsbruck again to be formally appointed and was possibly appointed in Augsburg too. His duties were not arduous, so that he was able to live by turns in Vienna, Innsbruck, Constance (all connected with the court), and Italy. He also spent much time at the court of Ercole d'Este, Duke of Ferrara. During his last years he remained in Florence.

Works Church music many Masses, about 50 motets, sequences, Lamentation Oratio Jeremiae, 58 four-part settings of the offices under the title Choralis Constantinus, the first polyphonic cycle of liturgical works for the ecclesiastical year; four-part Monodia on the death of Lorenzo de' Medici (words by Poliziano).

Other many German, Italian, French, and Latin songs (including ‘Innsbruck, ich muss dich lassen’, which may not be his own tune), 58 instrumental pieces in three–five parts, 29 domestic pieces in two–five parts.