Known as the theorist of the Third Stream, French horn player, composer, author, and musicologist Gunther Schuller has died in a Boston hospital at the age of 89. There is a full New York Times obituary here.

A musical polymath, as a French horn player he played with the American Ballet theatre and Cincinnati Symphony and later the Metropolitan Opera Orchestra. He also wrote a standard text for the instrument. Beyond classical music he became friends with the Modern Jazz Quartet's John Lewis and appeared on Miles Davis’ Birth of the Cool at the beginning of the 1950s. Schuller also recorded with Mingus, and with Lewis founded the Modern Jazz Society, later the Jazz and Classical Music Society.

Schuller became president of the New England Conservatory and remained there for a decade from 1967 to 1977, and did much to academise jazz and classical music based on what had become known as the Third Stream, a term going back to the the late-1950s. The NY Times obituary linked to above quotes Schuller describing the concept itself: “The Third Stream movement inspires composers, improvisers and players to work together toward the goal of a marriage of musics, whether ethnic or otherwise, that have been kept apart by the tastemakers — fusing them in a profound way. And I think it’s appropriate that this has happened in this country, because America is the original cultural melting pot.”

Schuller’s honours included winning the Pulitzer Prize for Music for Of Reminiscences and Reflections, and a MacArthur “genius” grant in the 1990s.