NEW YORK — Dennis Johnson, a composer who in 1959 wrote a trailblazing minimalist work, a six-hour piano meditation of repeated notes and long pauses that went unheard for 50 years before being rediscovered, died Dec. 20 in Morgan Hill, Calif. He was 80.
His half brother, Don Wilson, said the cause was complications of dementia.
Until 10 years ago, long after Mr. Johnson had dropped composing for a career as a mathematician, his music was known only by reputation. References to it were found in the writings of composer La Monte Young, who described Mr. Johnson as one of his closest musical allies when they were students at the University of California Los Angeles.
Young is a founder of minimalism, a genre of composition marked by repetition, gradual development, and sometimes spare harmonies. Some of the most important contemporary composers, including John Adams, Steve Reich, and Philip Glass, are at times associated with the movement or at least have incorporated such elements in their work.
Young is credited with composing the first minimalist work, his String Trio of 1958, which unfolded so slowly that listeners focused less on its sequence of notes than on its long, sustained tones and glacial pace.
A year later, Mr. Johnson produced “November,” his piano work, which also moves glacially, starting with just two notes — a rising minor third — repeated several times before new material is added, in a process that yielded a flow of individual tones, sustained chords, and silences.
Mr. Johnson described his compositional method in a 2013 interview with the music magazine The Wire: “I would just sit down at the piano and diddle, and listen, and it would slowly grow, like out of a seed,” he said. “Even now, when I do mathematics, it seems to be that way.”
Mr. Johnson’s innovations were repetition and generally consonant harmonies. Young has said that “November” influenced his own six-hour magnum opus, “The Well-Tuned Piano” (1964), considered an early landmark of the genre.
But for the next 50 years “November” was virtually unknown. The path to revival began in 1992, when Young gave critic and composer Kyle Gann a cassette tape with a partial performance, by Mr. Johnson, running 112 minutes.
Gann decided to reconstruct the score, using the tape and a handful of pages that Mr. Johnson had sent him detailing many of the work’s motifs as well as performance instructions. Gann performed a tag-team version of the piece with the pianist Sarah Cahill at the Second International Conference on Minimalist Music, at the University of Missouri Kansas City in 2009.
That performance led to a 2013 recording by R. Andrew Lee for Irritable Hedgehog, a new-music label. Gann’s reconstruction has also been recorded by Dutch pianist Jeroen van Veen.
Though the score was unknown to most musicians until the release of Lee’s recording, its minimalist qualities — and its influence on Young — have led to a reconsideration of minimalism’s early history.