Editing Heinrich Isaac (section)

== Compositions ==

Isaac was one of the most prolific composers of the time, producing an extraordinarily diverse output, including almost all the forms and styles current at the time; only Lassus, at the end of the 16th century, had a wider overall range.<ref>Dunning, "Low Countries, I.1: Art music, Netherlands to 1600." Grove, 1980</ref> Music composed by Isaac included [[mass (music)|masses]], [[motet]]s, songs in French, German, and Italian, as well as [[musical instrument|instrumental]] music. His best known work may be the song "[[Innsbruck, ich muss dich lassen]]", of which he made at least two versions. It is possible, however, that the [[melody]] itself is not by Isaac, and only the setting is original.<ref>Strohm, "Heinrich Isaac", Grove online</ref> The same melody was later used as the theme for the [[Lutheran hymn]] "[[O Welt, ich muss dich lassen]]", which was the basis of works by [[Johann Sebastian Bach]], including his ''[[St Matthew Passion]]''<ref name="Dürr">{{cite book |last=Dürr |first=Alfred |author-link=Alfred Dürr |title=Die Kantaten von Johann Sebastian Bach |year=1971 |publisher=Bärenreiter-Verlag |oclc=523584 |volume=1 |language=de}}</ref><ref>{{cite web|url=http://www.bach-cantatas.com/CM/O-Welt-ich-muss.htm |title=Chorale Melodies used in Bach's Vocal Works / O Welt, ich muss dich lassen |publisher=bach-cantatas.com |year=2009 |access-date=9 January 2012}}</ref> and [[Johannes Brahms]].

Of his settings of the ordinary of the mass, 36 survive; others are believed to have been lost. Numerous individual movements of masses survive as well. But it is composition of music for the [[Proper (liturgy)|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.<ref name="Strohm, Grove online"/>

Isaac is held in high regard for his ''[[Choralis Constantinus]]''. It is a huge anthology of over 450 chant-based polyphonic motets for the Proper of the Mass. 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. Isaac was in Konstanz because Maximilian had called a meeting of the [[Imperial Diet (Holy Roman Empire)|Reichstag]] (German Parliament of nobles) there and Isaac was on hand to provide music for the Imperial court chapel choir. After the deaths of both Maximilian and Isaac, [[Ludwig Senfl]], who had been Isaac's pupil as a member of the Imperial court choir, gathered all the Isaac settings of the Proper and placed them into liturgical order for the church year. But the anthology was not published until 1555, after Senfl's death, by which time the reforms of the [[Council of Trent]] had made many of the texts obsolete. The motets remain some of the finest examples of chant-based Renaissance polyphony in existence.

Isaac composed a 6-voice motet ''Angeli Archangeli'' for the Feast of All Saint's Day, honoring angels, archangels, and all other saints.<ref>Angels, Archangels, and a Woman in Distress: The Meaning of Isaac’s Angeli archangeli. The journal of musicology: A quarterly review of music history, criticism, analysis, and performance practice. Fall 2004. David Rothenberg.</ref> Another famous motet by Isaac is ''Optime pastor'' (''Optime divino''), written for the accession to the papacy of Medici pope [[Pope Leo X|Leo X]].<ref>D'Accone, "Medici", Grove online</ref> This motet compares the Pope to a shepherd capable of soothing all of his flock and binding them together.

While in the service of the Medici in Florence, Isaac wrote a lament on the death of [[Lorenzo de' Medici]], ''Quis dabit capiti meo aquam'' (1492), which set words by Lorenzo's favorite poet, [[Angelo Poliziano]].<ref name="Strohm, Grove online"/>