Heinrich Isaac
A writer in the Milanese Revista critica della letteratura italiana, June 1886, speculated that this patronymic might be connected to 'Huygens' and discovered the name "Isaacke" in the town archives of Bruges.
Heinrich Isaac's career spanned well over thirty years and allowed him to travel far from his homeland of Flanders into Germany, Italy, and Austria, as well as other parts of central Europe.
Isaac was probably writing music by the 1470s, and the first document mentioning his name dates back to 15 September 1484, placing him in Innsbruck as a singer for Duke Sigismund of Austria, of the House of Habsburg.
Several documents illustrate Isaac's long stay in Florence under the employment of Santa Maria del Fiore and Santissima Annunziata as a singer, and also suggest that he may have developed a close working-relationship with Lorenzo de' Medici.
Recently discovered documents offer evidence that Isaac began making yearly payments to the confraternity of Santa Barbara for mutual assistance.
[7] On 15 August 1502, Isaac wrote his first will which included names of his proprietors, alluding to the fact that he was doing well to care for his wife and property should anything happen to him.
"[8] Between 1505 and 1512 there are records of Isaac having dealings in Augsburg, Florence and Constance (see Konstanz), the latter in which he compiled his largest set of works: Choralis Constantinus.
This monumental collection of mass propers was commissioned by the Constance cathedral on 14 April 1508 and completed by Isaac and his student Ludwig Senfl by the winter of 1509.
On the recommendation of Pope Leo X and of his brother Giuliano de' Medici,[9] he was given an honorary position as chief of the Chapel of Polyphonic Music at Santa Maria del Fiore on 30 May 1514, which served as a pension.
A last posthumous donation was made to the confraternity of Santa Barbara in the amount of five florins, which was equal to one quarter the value of Isaac's home.
But it is composition of music for the Proper of the Mass – the portion of the liturgy which changed on different days, unlike the ordinary, which remained constant – which gave him his greatest fame.
The huge cycle of motets which he wrote for the mass Proper, the Choralis Constantinus, and which he left incomplete at his death, would have supplied music for 100 separate days of the year.
It had its origins in a commission that Isaac received from the Cathedral in Konstanz, Germany in April 1508 to set many of the Propers unique to the local liturgy.
He was the first significant master of the Franco-Flemish polyphonic style who both lived in German-speaking areas, and whose music was widely distributed there.
The Austrian serialist composer Anton Webern (1883–1945) gained his PhD on Isaac's Choralis Constantinus, with Prof. Guido Adler, the doyen of musicology in Austria and Germany.
