• Composer Stephen Michael "Steve" Reich, 1936
• Composer Philip Glass, 1937

His innovations include using tape loops to create phasing patterns (for example, his early compositions "It's Gonna Rain" and "Come Out"), and the use of simple, audible processes to explore musical concepts (for instance, "Pendulum Music" and "Four Organs"). These compositions, marked by their use of repetitive figures, slow harmonic rhythm and canons, have significantly influenced contemporary music, especially in the US. Reich's work took on a darker character in the 1980s with the introduction of historical themes as well as themes from his Jewish heritage, notably the Grammy Award winning Different Trains.

Reich's style of composition influenced many other composers and musical groups. Reich has been described, in The Guardian by music critic Andrew Clements, as one of "a handful of living composers who can legitimately claim to have altered the direction of musical history", and the critic Kyle Gann has said Reich "may...be considered, by general acclamation, America's greatest living composer."

On January 25, 2007, Reich was named the 2007 recipient of the Polar Music Prize, together with jazz saxophonist Sonny Rollins. On April 20, 2009, Reich was awarded the 2009 Pulitzer Prize for Music for his Double Sextet.

Reich was born in New York City to the Broadway lyricist June Sillman. When he was one year old, his parents divorced, and Reich divided his time between New York and California. He was given piano lessons as a child and describes growing up with the "middle class favorites", having no exposure to music written before 1750 or after 1900. At the age of 14 he began to study music in earnest, after hearing music from the Baroque period and earlier, as well as music of the 20th century. Reich studied drums with Roland Kohloff in order to play jazz. While attending Cornell University, he took some music courses, but he graduated in 1957 with a B.A. in Philosophy. Reich's B.A. thesis was on Ludwig Wittgenstein; later he would set texts by that philosopher to music in Proverb (1995) and You Are (variations) (2006).

For a year following graduation, Reich studied composition privately with Hall Overton before he enrolled at Juilliard to work with William Bergsma and Vincent Persichetti (1958 - 1961). Subsequently he attended Mills College in Oakland, California, where he studied with Luciano Berio and Darius Milhaud (1961 - 1963) and earned a master's degree in composition. At Mills, Reich composed Melodica for melodica and tape, which appeared in 1986 on the three - LP release Music from Mills.

Reich worked with the San Francisco Tape Music Center along with Pauline Oliveros, Ramon Sender, Morton Subotnick and Terry Riley. He was involved with the premiere of Riley's In C and suggested the use of the eighth note pulse, which is now standard in performance of the piece.

Reich's early forays into composition involved experimentation with twelve - tone composition, but he found the rhythmic aspects of the twelve - tone series more interesting than the melodic aspects. Reich also composed film soundtracks for Plastic Haircut, Oh Dem Watermelons, and Thick Pucker, three films by Robert Nelson. The soundtrack of Plastic Haircut, composed in 1963, was a short tape collage, possibly Reich's first. The Watermelons soundtrack used two old Stephen Foster minstrel tunes as its basis, and used repeated phrasing together in a large five part canon. The music for Thick Pucker arose from street recordings Reich made walking around San Francisco with Nelson, who filmed in black and white 16mm. This film no longer survives. A fourth film from 1965, about 25 minutes long and tentatively entitled "Thick Pucker II", was assembled by Nelson from outtakes of that shoot and more of the raw audio Reich had recorded. Nelson was not happy with the resulting film and never showed it.

Reich was influenced by fellow minimalist Terry Riley, whose work In C combines simple musical patterns, offset in time, to create a slowly shifting, cohesive whole. Reich adopted this approach to compose his first major work, It's Gonna Rain. Composed in 1965, the piece used a fragment of a sermon about the end of the world given by a black Pentecostal street preacher known as Brother Walter. Reich built on his early tape work, transferring the last three words of the fragment, "it's gonna rain!", to multiple tape loops which gradually move out of phase with one another.

The 13-minute "Come Out" (1966) uses similarly manipulated recordings of a single spoken line given by Daniel Hamm, one of the falsely accused Harlem Six, who was severely injured by police. The survivor, who had been beaten, punctured a bruise on his own body to convince police about his beating. The spoken line includes the phrase "to let the bruise’s blood come out to show them." Reich rerecorded the fragment "come out to show them" on two channels, which are initially played in unison. They quickly slip out of sync; gradually the discrepancy widens and becomes a reverberation. The two voices then split into four, looped continuously, then eight, and continues splitting until the actual words are unintelligible, leaving the listener with only the speech's rhythmic and tonal patterns.

A similar, lesser known example of process music is "Pendulum Music" (1968), which consists of the sound of several microphones swinging over the loudspeakers to which they are attached, producing feedback as they do so. "Pendulum Music" has never been recorded by Reich himself, but was introduced to rock audiences by Sonic Youth in the late 1990s.

Reich's first attempt at translating this phasing technique from recorded tape to live performance was the 1967 Piano Phase, for two pianos. In Piano Phase the performers repeat a rapid twelve - note melodic figure, initially in unison. As one player keeps tempo with robotic precision, the other speeds up very slightly until the two parts line up again, but one sixteenth note apart. The second player then resumes the previous tempo. This cycle of speeding up and then locking in continues throughout the piece; the cycle comes full circle three times, the second and third cycles using shorter versions of the initial figure. Violin Phase, also written in 1967, is built on these same lines. Piano Phase and Violin Phase both premiered in a series of concerts given in New York art galleries.

Reich also tried to create the phasing effect in a piece "that would need no instrument beyond the human body". He found that the idea of phasing was inappropriate for the simple ways he was experimenting to make sound. Instead, he composed Clapping Music (1972), in which the players do not phase in and out with each other, but instead one performer keeps one line of a 12 - quaver - long (12 - eighth - note - long) phrase and the other performer shifts by one quaver beat every 12 bars, until both performers are back in unison 144 bars later.

The 1967 prototype piece Slow Motion Sound was not performed although Chris Hughes performed it 27 years later as "Slow Motion Blackbird" on his Reich influenced 1994 album Shift. It introduced the idea of slowing down a recorded sound until many times its original length without changing pitch or timbre, which Reich applied to Four Organs (1970), which deals specifically with augmentation. The piece has maracas playing a fast eighth note pulse, while the four organs stress certain eighth notes using an 11th chord. This work therefore dealt with repetition and subtle rhythmic change. It is unique in the context of Reich's other pieces in being linear as opposed to cyclic like his earlier works — the superficially similar Phase Patterns, also for four organs but without maracas, is (as the name suggests) a phase piece similar to others composed during the period. Four Organs was performed as part of a Boston Symphony Orchestra program, and was Reich's first composition to be performed in a large traditional setting.

In 1971, Reich embarked on a five week trip to study music in Ghana, during which he learned from the master drummer Gideon Alorwoyie. Reich also studied Balinese gamelan in Seattle. From his African experience, as well as A. M. Jones's Studies in African Music about the music of the Ewe people, Reich drew inspiration for his 90 minute piece Drumming, which he composed shortly after his return. Composed for a nine piece percussion ensemble with female voices and piccolo, Drumming marked the beginning of a new stage in his career, for around this time he formed his ensemble, Steve Reich and Musicians, and increasingly concentrated on composition and performance with them. Steve Reich and Musicians, which was to be the sole ensemble to interpret his works for many years, still remains active with many of its original members.

After Drumming, Reich moved on from the "phase shifting" technique that he had pioneered, and began writing more elaborate pieces. He investigated other musical processes such as augmentation (the temporal lengthening of phrases and melodic fragments). It was during this period that he wrote works such as Music for Mallet Instruments, Voices and Organ (1973) and Six Pianos (1973).

In 1974, Reich began writing what many would call his seminal work, Music for 18 Musicians. This piece involved many new ideas, although it also hearkened back to earlier pieces. It is based on a cycle of eleven chords introduced at the beginning (called "Pulses"), followed by a small section of music based on each chord ("Sections I-XI"), and finally a return to the original cycle ("Pulses"). This was Reich's first attempt at writing for larger ensembles. The increased number of performers resulted in more scope for psychoacoustic effects, which fascinated Reich, and he noted that he would like to "explore this idea further". Reich remarked that this one work contained more harmonic movement in the first five minutes than any other work he had written. Steve Reich and Musicians made the premier recording of this work on ECM Records.

Reich explored these ideas further in his frequently recorded pieces Music for a Large Ensemble (1978) and Octet (1979). In these two works, Reich experimented with "the human breath as the measure of musical duration … the chords played by the trumpets are written to take one comfortable breath to perform". Human voices are part of the musical palette in Music for a Large Ensemble but the wordless vocal parts simply form part of the texture (as they do in Drumming). With Octet and his first orchestral piece Variations for Winds, Strings and Keyboards (also 1979), Reich's music showed the influence of Biblical cantillation, which he had studied in Israel since the summer of 1977. After this, the human voice singing a text would play an increasingly important role in Reich's music.

In 1974 Reich published a book, Writings About Music, containing essays on his philosophy, aesthetics, and musical projects written between 1963 and 1974. An updated and much more extensive collection, Writings On Music, was published in 2002.

Reich's work took on a darker character in the 1980s with the introduction of historical themes as well as themes from his Jewish heritage. Tehillim (1981), Hebrew for psalms, is the first of Reich's works to draw explicitly on his Jewish background. The work is in four parts, and is scored for an ensemble of four women's voices (one high soprano, two lyric sopranos and one alto), piccolo, flute, oboe, English horn, two clarinets, six percussion (playing small tuned tambourines without jingles, clapping, maracas, marimba, vibraphone and crotales), two electronic organs, two violins, viola, cello and double bass, with amplified voices, strings, and winds. A setting of texts from psalms 19:2–5 (19:1–4 in Christian translations), 34:13–15 (34:12–14), 18:26–27 (18:25–26), and 150:4–6, Tehillim is a departure from Reich's other work in its formal structure; the setting of texts several lines long rather than the fragments used in previous works makes melody a substantive element. Use of formal counterpoint and functional harmony also contrasts with the loosely structured minimalist works written previously.

Different Trains (1988), for string quartet and tape, uses recorded speech, as in his earlier works, but this time as a melodic rather than a rhythmic element. In Different Trains Reich compares and contrasts his childhood memories of his train journeys between New York and California in 1939 - 1941 with the very different trains being used to transport contemporaneous European children to their deaths under Nazi rule. The Kronos Quartet recording of Different Trains was awarded the Grammy Award for Best Classical Contemporary Composition in 1990. The composition was described by Richard Taruskin as "the only adequate musical response - one of the few adequate artistic responses in any medium - to the Holocaust", and he credited the piece with earning Reich a place among the great composers of the 20th century.

In 1993, Reich collaborated with his wife, the video artist Beryl Korot, on an opera, The Cave, which explores the roots of Judaism, Christianity and Islam through the words of Israelis, Palestinians and Americans, echoed musically by the ensemble. The work, for percussion, voices and strings, is a musical documentary, named for the Cave of Machpelah in Hebron, where a mosque now stands and Abraham is said to have been buried. The two collaborated again on the opera Three Tales, which concerns the Hindenburg disaster, the testing of nuclear weapons on Bikini Atoll, and other more modern concerns, specifically Dolly the sheep, cloning, and the technological singularity.

As well as pieces using sampling techniques, like Three Tales and City Life (1994), Reich also returned to composing purely instrumental works for the concert hall, starting with Triple Quartet (1998) written for the Kronos Quartet that can either be performed by string quartet and tape, three string quartets or 36 piece string orchestra. According to Reich, the piece is influenced by Bartók's and Alfred Schnittke's string quartets, and Michael Gordon's Yo Shakespeare. This series continued with Dance Patterns (2002), Cello Counterpoint (2003), and sequence of works centered around Variations: You Are (Variations) (2004) (a work which looks back to the vocal writing of works like Tehillim or The Desert Music), Variations for Vibes, Pianos, and Strings (2005, for the London Sinfonietta) and Daniel Variations (2006).

Invited by Walter Fink, he was the 12th composer featured in the annual Komponistenporträt of the Rheingau Musik Festival in 2002.

In an interview with The Guardian, Reich stated that he continued to follow this direction with his piece Double Sextet (2007), which was commissioned by eighth blackbird, an American ensemble consisting of the instrumental quintet (flute, clarinet, violin or viola, cello and piano) of Schoenberg's piece Pierrot Lunaire (1912) plus percussion. Reich stated that he was thinking about Stravinsky's Agon (1957) as a model for the instrumental writing.

Reich was awarded the 2009 Pulitzer Prize for Music, on April 20, 2009, for Double Sextet.

December 2010 Nonesuch Records and Indaba Music held a community remix contest in which over 250 submissions were received, and Steve Reich and Christian Carey judged the finals. Reich spoke in a related BBC interview that once he composed a piece he would not alter it again himself; "When it's done, it's done," he said. On the other hand he acknowledged that remixes have an old tradition, e.g., famous religious music pieces where melodies were further developed into new songs.

In May 2011, Steve Reich received an honorary doctorate from the New England Conservatory of Music.

Reich's style of composition has influenced many other composers and musical groups, including John Adams, the progressive rock band King Crimson, the new age guitarist Michael Hedges, the art - pop and electronic musician Brian Eno, the experimental art / music group The Residents, the composers associated with the Bang on a Can festival (including David Lang, Michael Gordon and Julia Wolfe), and numerous indie rock musicians including songwriter Sufjan Stevens and instrumental ensembles Tortoise, The Mercury Program (themselves influenced by Tortoise), Godspeed You! Black Emperor composed a song, unreleased, entitled "Steve Reich".

John Adams commented, "He didn't reinvent the wheel so much as he showed us a new way to ride." He has also influenced visual artists such as Bruce Nauman, and many notable choreographers have made dances to his music, Eliot Feld, Jiří Kylián, Douglas Lee and Jerome Robbins among others; he has expressed particular admiration of Anne Teresa De Keersmaeker's work set to his pieces.

In featuring a sample of Reich's Electric Counterpoint (1987) the British ambient techno act the Orb exposed a new generation of listeners to the composer's music with its 1990 production “Little Fluffy Clouds.” Further acknowledgment of Reich's influence on various electronic dance music producers came with the release in 1999 of Reich Remixed, an album that featured reinterpretations by artists such as DJ Spooky, Kurtis Mantronik, Ken Ishii, and Coldcut, among others.

Reich often cited Pérotin, J.S. Bach, Debussy, Bartók, and Stravinsky as composers whom he admired, whose tradition of which he wished as a young composer to become part. Jazz is a major part of the formation of Reich's musical style, and two of the earliest influences on his work were vocalists Ella Fitzgerald and Alfred Deller, whose emphasis on the artistic capabilities of the voice alone with little vibrato or other alteration was an inspiration to his earliest works. John Coltrane's style, which Reich has described as "playing a lot of notes to very few harmonies", also had an impact; of particular interest was the album Africa / Brass, which "was basically a half - an - hour in F." Reich's influence from jazz includes its roots, also, from the West African music he studied in his readings and visit to Ghana. Other important influences are Kenny Clarke and Miles Davis, and visual artist friends such as Sol LeWitt and Richard Serra. Reich contributed the introduction to Sound Unbound: Sampling Digital Music and Culture edited by Paul D. Miller, a.k.a. DJ Spooky.

Reich had the world premiere of a piece, WTC 9/11, written for String Quartet and Tape, a similar instrumentation to that of Different Trains. It premiered in March 2011 by the Kronos Quartet, at Duke University, North Carolina, USA.

[...] I drove a cab in San Francisco, and in New York I worked as a part time social worker. Phil Glass and I had a moving company for a short period of time. I did all kinds of odd jobs [...] I started making a living as a performer in my own ensemble. I would never have thought that it was how I was going to survive financially. It was a complete wonder.
—From an interview with Richard Kessler, 1998

The point is, if you went to Paris and dug up Debussy and said, 'Excusez-moi Monsieur…are you an impressionist?' he'd probably say 'Merde!' and go back to sleep. That is a legitimate concern of musicologists, music historians, and journalists, and it's a convenient way of referring to me, Riley, Glass, La Monte Young [...] it's become the dominant style. But, anybody who's interested in French Impressionism is interested in how different Debussy and Ravel and Satie are — and ditto for what's called minimalism. [...] Basically, those kind of words are taken from painting and sculpture, and applied to musicians who composed at the same period as that painting and sculpture was made [...].
—From an Interview with Rebecca Y. Kim, 2000

All musicians in the past, starting with the middle ages were interested in popular music. (...) Béla Bartók's music is made entirely of sources from Hungarian folk music. And Igor Stravinsky, although he lied about it, used all kinds of Russian sources for his early ballets. Kurt Weill's great masterpiece Dreigroschenoper is using the cabaret - style of the Weimar Republic and that's why it is such a masterpiece. Only artificial division between popular and classical music happened unfortunately through the blindness of Arnold Schoenberg and his followers to create an artificial wall, which never existed before him. In my generation we tore the wall down and now we are back to the normal situation, for example if Brian Eno or David Bowie come to me, and if popular musicians remix my music like The Orb or DJ Spooky it is a good thing. This is a natural normal regular historical way.
—From an Interview with Jakob Buhre

He distanced himself from the "minimalist" label, describing himself instead as a composer of "music with repetitive structures." Though his early mature music shares much with what is normally called "minimalist", he later evolved stylistically. He described himself as a "Classicist", pointing out that he was trained in harmony and counterpoint and studied such composers as Franz Schubert, Johann Sebastian Bach and Wolfgang Amadeus Mozart with Nadia Boulanger.

Glass has been a prolific composer: he wrote works for the musical group which he founded, the Philip Glass Ensemble, as well as operas, musical theater works, ten symphonies, eleven concertos, solo works, chamber music including string quartets and instrumental sonatas, and film scores. Three of his film scores have been nominated for Academy Awards.

Glass counts many artists among his friends and collaborators, including visual artists (Richard Serra, Chuck Close), writers (Doris Lessing, David Henry Hwang, Allen Ginsberg), film and theater directors (including Errol Morris, Robert Wilson, JoAnne Akalaitis, Godfrey Reggio, Paul Schrader, Martin Scorsese, Christopher Hampton, Bernard Rose, and many others), choreographers (Lucinda Childs, Jerome Robbins, Twyla Tharp), and musicians and composers (Ravi Shankar, David Byrne, the conductor Dennis Russell Davies, Foday Musa Suso, Laurie Anderson, Linda Ronstadt, Paul Simon, Joan LaBarbara, Arthur Russell, David Bowie, Brian Eno, Roberto Carnevale, Patti Smith, Aphex Twin, Lisa Bielawa, Andrew Shapiro, John Moran, Bryce Dessner and Nico Muhly). Among other collaborators are Glass's fellow New Yorker Woody Allen, Stephen Colbert, and poet and songwriter Leonard Cohen.

Glass was born on January 31, 1937, in Baltimore, Maryland, the son of Ida (née Gouline) and Benjamin Charles Glass, and the grandson of Jewish immigrants from Lithuania. His father owned a record store, and consequently Glass's record collection consisted to a large extent of unsold records, including modern music (such as Hindemith, Bartók, Schoenberg, Shostakovich) and Western classical music (including Ludwig van Beethoven's String Quartets and Schubert's B♭ Piano Trio, which he cited as a "big influence"), at a very early age. He then studied the flute as a child at the Peabody Conservatory of Music and entered an accelerated college program at the University of Chicago at the age of 15, where he studied Mathematics and Philosophy. In Chicago he discovered the serialism of Webern and composed a twelve - tone string trio. In 1954 Glass went to Paris for the first time, encountering the films of Jean Cocteau, which made a lasting impression on him. He visited artists' studios and saw their work; "the bohemian life you see in [Cocteau's] Orphée was the life I ... was attracted to, and those were the people I hung out with."

Glass then went on to the Juilliard School of Music where the keyboard became his main instrument. His composition teachers included Vincent Persichetti and William Bergsma, while fellow students included Steve Reich. During this time, in 1959, he was a winner in the BMI Foundation's BMI Student Composer Awards, one of the most prestigious international prizes for young composers. In the summer of 1960, he studied with Darius Milhaud at the summer school of the Aspen Music Festival and composed a Violin Concerto for a fellow student, Dorothy Pixley - Rothschild. After leaving Juilliard in 1962, Glass moved to Pittsburgh and worked as a school - based composer - in - residence in the public school system, composing various choral, chamber and orchestral music.

In 1964, Glass received a Fulbright Scholarship and went to Paris, where he studied with the eminent composition teacher Nadia Boulanger from autumn of 1964 to summer of 1966. Glass's years in Paris as a student made a lasting impression and influenced his work ever since, as the composer admitted in 1979: "The composers I studied with Boulanger are the people I still think about most — Bach and Mozart."

Glass later stated in his autobiography Music by Philip Glass (1987) that the new music performed at Pierre Boulez's Domaine Musical concerts in Paris lacked any excitement for him (with the notable exceptions of music by John Cage and Morton Feldman), but he was deeply impressed by new films and theater performances. He encountered revolutionary films of the French New Wave, such as those of Jean-Luc Godard and François Truffaut, which upended the rules set by an older generation of artists, and Glass made friends with American visual artists (the sculptor Richard Serra and his wife Nancy Graves), actors and directors (JoAnne Akalaitis, Ruth Maleczech, David Warrilow and Lee Breuer, with whom Glass later founded the experimental theater group Mabou Mines). Together with Akalaitis (they married in 1965), Glass in turn attended performances by theater groups including Jean - Louis Barrault's Odéon theater, The Living Theatre and the Berliner Ensemble in 1964 to 1965. These significant encounters resulted in a collaboration with Breuer for which Glass contributed music for a 1965 staging of Samuel Beckett's Comédie (Play, 1963). The resulting piece (written for two soprano saxophones) was directly influenced by the play's open - ended, repetitive and almost musical structure and was the first one of a series of four early pieces in a minimalist, yet still dissonant, idiom. After Play, Glass also acted in 1966 as music director of a Breuer production of Brecht's Mother Courage and Her Children, featuring the theater score by Paul Dessau.

In parallel with his early excursions in experimental theater, Glass worked in winter 1965 and spring 1966 as a music director and composer on a film score (Chappaqua, Conrad Rooks, 1966) with Ravi Shankar and Alla Rakha, which added another important influence on Glass's musical thinking. His distinctive style arose from his work with Shankar and Rakha and their perception of rhythm in Indian music as being entirely additive. He renounced all his compositions in a moderately modern style resembling Milhaud's, Aaron Copland's, and Samuel Barber's, and began writing pieces based on repetitive structures of Indian music and a sense of time influenced by Samuel Beckett: a piece for two actresses and chamber ensemble, a work for chamber ensemble and his first numbered string quartet (No.1, 1966).

Glass then left Paris for northern India in 1966, where he came in contact with Tibetan refugees and began to gravitate towards Buddhism. He met Tenzin Gyatso, the 14th Dalai Lama, in 1972, and has been a strong supporter of the Tibetan independence ever since.

Shortly after arriving in New York City in March 1967, Glass attended a performance of works by Steve Reich (including the ground breaking minimalist piece Piano Phase), which left a deep impression on him; he simplified his style and turned to a radical "consonant vocabulary". Finding little sympathy from traditional performers and performance spaces, Glass eventually formed an ensemble with fellow ex-students Steve Reich, Jon Gibson, and others, and began performing mainly in art galleries and studio lofts of SoHo. The visual artist Richard Serra provided Glass with Gallery contacts, while both collaborated on various sculptures, films and installations; from 1971 to 1974 he became Serra's regular studio assistant.

Between summer of 1967 and the end of 1968, Glass composed nine works, including Strung Out (for amplified solo violin, composed in summer of 1967), Gradus (for solo saxophone, 1968), Music in the Shape of a Square (for two flutes, composed in May 1968, an homage to Erik Satie), How Now (for solo piano, 1968) and 1+1 (for amplified tabletop, November 1968) which were "clearly designed to experiment more fully with his new - found minimalist approach". The first concert of Glass's new music was at Jonas Mekas's Film - Makers Cinemathèque (Anthology Film Archives) in September 1968. This concert included the first work of this series with Strung Out (performed by the violinist Pixley - Rothschild) and Music in the Shape of a Square (performed by Glass and Gibson). The musical scores were tacked on the wall, and the performers had to move while playing. Glass's new works met with a very enthusiastic response by the audience which consisted mainly of visual and performance artists who were highly sympathetic to Glass's reductive approach.

Apart from his music career, Glass had a moving company with his cousin, the sculptor Jene Highstein, and worked as a plumber and cab driver (in 1973 to 1978). During this time he made friends with other New York based artists such as Sol LeWitt, Nancy Graves, Michael Snow, Bruce Nauman, Laurie Anderson, and Chuck Close, who created a now famous portrait of Glass. (Glass returned the favor in 2005 with A Musical Portrait of Chuck Close for piano.)

With 1+1 and Two Pages (composed in February 1969) Glass turned to a more "rigorous approach" to his "most basic minimalist technique, additive process", pieces which were followed in the same year by Music in Contrary Motion and Music in Fifths (a kind of homage to his composition teacher Nadia Boulanger, who pointed out "hidden fifths" in his works but regarded them as cardinal sins). Eventually Glass's music grew less austere, becoming more complex and dramatic, with pieces such as Music in Similar Motion (1969), and Music with Changing Parts (1970). These pieces were performed by The Philip Glass Ensemble in the Whitney Museum of American Art in 1969 and in the Solomon R. Guggenheim Museum in 1970, often encountering hostile reaction from critics, but Glass's music was also met with enthusiasm from younger artists such as Brian Eno and David Bowie (at the Royal College of Art ca. 1970). Eno described this encounter with Glass's music as one of the "most extraordinary musical experiences of [his] life", as a "viscous bath of pure, thick energy", concluding "this was actually the most detailed music I'd ever heard. It was all intricacy, exotic harmonics". In 1970 Glass returned to the theater, composing music for the theater group Mabou Mines, resulting in his first minimalist pieces employing voices: Red Horse Animation and Music for Voices (both 1970, and premiered at the Paula Cooper Gallery).

After differences of opinion with Steve Reich in 1971, Glass formed the Philip Glass Ensemble (while Reich formed Steve Reich and Musicians), an amplified ensemble including keyboards, wind instruments (saxophones, flutes), and soprano voices.

Glass's music for his ensemble culminated in the four hour long Music in Twelve Parts (1971 - 1974), which began as a single piece with twelve instrumental parts but developed into a cycle that summed up Glass's musical achievement since 1967, and even transcended it – the last part features a twelve - tone theme, sung by the soprano voice of the ensemble. "I had broken the rules of modernism and so I thought it was time to break some of my own rules", according to Glass. Though he found the term minimalist inaccurate to describe his later work, Glass accepted this term for pieces up to and including Music in 12 Parts, excepting this last part which "was the end of minimalism" for Glass. As he pointed out: "I had worked for eight or nine years inventing a system, and now I'd written through it and come out the other end."

Glass continued his work with a series of instrumental works, called Another Look at Harmony (1975 - 1977). For Glass this series demonstrated a new start, hence the title: "What I was looking for was a way of combining harmonic progression with the rhythmic structure I had been developing, to produce a new overall structure. (...) I'd taken everything out with my early works and it was now time to decide just what I wanted to put in — a process that would occupy me for several years to come." Parts 1 and 2 of "Another Look at Harmony" were included in a collaboration with Robert Wilson, a piece of musical theater that was later designated by Glass as the first opera of his portrait opera trilogy: Einstein on the Beach. Composed in Spring to Fall of 1975 in close collaboration with Wilson, Glass's first opera was first premiered in summer 1976 at the Festival d'Avignon, and in November of the same year to a mixed and partly enthusiastic reaction from the audience at the Metropolitan Opera in New York City. Scored for the Philip Glass Ensemble, solo violin, chorus, and featuring actors (reciting texts by Christopher Knowles, Lucinda Childs and Samuel M. Johnson), Glass's and Wilson's essentially plotless opera was conceived as a "metaphorical look at Albert Einstein: scientist, humanist, amateur musician — and the man whose theories (...) led to the splitting of the atom", evoking nuclear holocaust in the climactic scene, as critic Tim Page pointed out. As with Another Look at Harmony, "Einstein added a new functional harmony that set it apart from the early conceptual works". Composer Tom Johnson came to the same conclusion, comparing the solo violin music to Johann Sebastian Bach, and the "organ figures (...) to those Alberti basses Mozart loved so much". The piece was praised by the Washington Post as "one of the seminal artworks of the century."

Einstein on the Beach was followed by further music for projects by the theater group Mabou Mines such as Dressed like an Egg (1975), and again music for plays and adaptations from prose by Samuel Beckett, such as The Lost Ones (1975), Cascando (1975), Mercier and Camier (1979). Glass also turned to other media; two multi - movement instrumental works for the Philip Glass Ensemble originated as music for film and TV: North Star (1977 for the Documentary "Mark di Suvero, sculptor" by Francois de Menil and Barbara Rose) and four short cues for Jim Henson's TV-series for children, Sesame Street, named Geometry of Circles (1979).

Another series, Fourth Series (1977 - 79), included music for chorus and organ ("Part One", 1977), organ and piano ("Part Two" and "Part Four", 1979), and music for a radio adaption of Constance DeJong's novel Modern Love ("Part Three", 1978). Part Two and Part Four were used (and hence renamed) in two dance productions by choreographer Lucinda Childs (who had already contributed to and performed in Einstein on the Beach). "Part Two" was included in Dance (a collaboration with visual artist Sol LeWitt, 1979), and "Part Four" was renamed as Mad Rush, and performed by Glass on several occasions such as the first public appearance of the 14th Dalai Lama in New York City in Fall 1981. The piece demonstrates Glass's turn to more traditional models: the composer added a conclusion to an open - structured piece which "can be interpreted as a sign that he [had] abandoned the radical non - narrative, undramatic approaches of his early period", as the pianist Steffen Schleiermacher points out.

In Spring 1978, Glass received a commission from the Netherlands Opera (as well as a Rockefeller Foundation grant) which "marked the end of his need to earn money from non - musical employment." With the commission Glass continued his work in music theater, composing his opera Satyagraha (composed in 1978 - 1979, premiered in 1980 at Rotterdam), based on the early life of Mahatma Gandhi in South Africa, Rabindranath Tagore and Martin Luther King Jr.. For Satyagraha , Glass worked in close collaboration with two "SoHo friends": the writer Constance deJong, who provided the libretto, and the set designer Robert Israel. This piece was in other ways a turning point for Glass, as it was his first work since 1963 scored for symphony orchestra, even if the most prominent parts were still reserved for solo voices and chorus. Shortly after completing the score in August 1979, Glass met the conductor Dennis Russell Davies, who he helped prepare for performances in Germany (using a piano - four - hands version of the score); together they started to plan another opera, to be premiered at the Stuttgart State Opera.

While planning a third part of his "Portrait Trilogy", Glass turned to smaller music theater projects such as the non - narrative Madrigal Opera (for six voices and violin and viola, 1980), and The Photographer, a biographic study on the photographer Eadweard Muybridge (1982). Glass also continued to write for the orchestra with his most famous film score to date, Koyaanisqatsi (Godfrey Reggio, 1981 - 1982). Some pieces which were not used in the film (such as Facades) eventually appeared on the album Glassworks (1982), which brought Glass's music to a wider public.

The "Portrait Trilogy" was completed with Akhnaten (1982 - 1983, premiered in 1984), a vocal and orchestral composition sung in Akkadian, Biblical Hebrew and Ancient Egyptian. In addition, this opera featured an actor reciting ancient Egyptian texts in the language of the audience. Akhnaten was commissioned by the Stuttgart Opera in a production designed by Achim Freyer. It premiered simultaneously at the Houston Opera in a production directed by David Freeman and designed by Peter Sellars. At the time of the commission, the Stuttgart Opera House was undergoing renovation, necessitating the use of a nearby playhouse with a smaller orchestra pit. Upon learning this, Glass and conductor Dennis Russell Davies visited the playhouse, placing music stands around the pit to determine how many players the pit could accommodate. The two found that they could not fit a full orchestra in the pit. Glass decided to eliminate the violins, which had the effect of "giving the orchestra a low, dark sound that came to characterize the piece and suited the subject very well." As Glass remarked in 1992, Akhnaten is significant in his work since it represents a "first extension out of a triadic harmonic language", an experiment with the polytonality of his teachers Persichetti and Milhaud, a musical technique which Glass compares to "an optical illusion, such as in the paintings of Josef Albers".

Glass again collaborated with Robert Wilson on another opera, the CIVIL warS (1983, premiered in 1984), which also functioned as the final part ("the Rome section) of Wilson's epic work by the same name, originally planned for an "international arts festival that would accompany the Olympic Games in Los Angeles". (Glass also composed a highly prestigious work for chorus and orchestra for the opening of the Games, The Olympian: Lighting of the Torch and Closing). The premiere of The CIVIL warS in Los Angeles never materialized and the opera was in the end premiered at the Opera of Rome. Glass's and Wilson's opera includes musical settings of Latin texts by the 1st century Roman playwright Seneca and allusions to the music of Giuseppe Verdi and from the American Civil War, featuring the 19th century figures Giuseppe Garibaldi and Robert E. Lee as characters.

In the mid 1980s, Glass produced "works in different media at an extraordinarily rapid pace". Projects from that period include music for dance (Dance Pieces, Jerome Robbins, 1983, and In the Upper Room, Twyla Tharp, 1986), and music for theater productions Endgame (1984), and Company (1983). Beckett vehemently disapproved of the production of Endgame at the American Repertory Theater (Cambridge, Massachusetts), which featured Joanne Akalaitis's direction and Glass's Prelude for timpani and double bass, but in the end, he authorized the music for Company, four short, intimate pieces for string quartet that were played in the intervals of the dramatization. This composition was initially regarded by the composer as a piece of Gebrauchsmusik ('music for use') — "like salt and pepper (...) just something for the table”, as he noted. Eventually Company was published as Glass's String Quartet No.2 and in a version for string orchestra, being performed by ensembles ranging from student orchestras to renowned ones such as the Kronos Quartet and the Kremerata Baltica.

This interest in writing for the string quartet and the string orchestra led to a chamber and orchestral film score for Mishima: A Life in Four Chapters (Paul Schrader, 1984 - 85), which Glass described as his "musical turning point" that developed his "technique of film scoring in a very special way".

Glass also dedicated himself to vocal works with two sets of songs, Three Songs for chorus (1984, settings of poems by Leonard Cohen, Octavio Paz and Raymond Levesque), and a song cycle initiated by CBS Masterworks Records: Songs from Liquid Days (1985), with texts by songwriters such as David Byrne, Paul Simon, in which the Kronos Quartet is featured (as it is in Mishima) in a prominent role. Glass also continued his series of operas with adaptations from literary texts such as The Juniper Tree (an opera collaboration with composer Robert Moran, 1984), Edgar Allan Poe's The Fall of the House of Usher (1987), and also worked with novelist Doris Lessing on the opera The Making Of The Representative For Planet 8 (1985 - 86, and performed by the Houston Grand Opera and English National Opera in 1988).

Compositions such as Company, Facades and String Quartet No.3 (the last two extracted from the scores to Koyaanisqatsi and Mishima) gave way to a series of works more accessible to ensembles such as the string quartet and symphony orchestra, in this returning to the structural roots of his student days. In taking this direction his chamber and orchestral works were also written in a more and more traditional and lyrical style. In these works, Glass often employs old musical forms such as the chaconne and the passacaglia – for instance in Satyagraha, the Violin Concerto No. 1 (1987), Symphony No. 3 (1995), Echorus (1995) and also recent works such as Symphony No. 8 (2005), and Songs and Poems for Solo Cello (2006).

A series of orchestral works that were originally composed for the concert hall commenced with the 3-movement Violin Concerto No. 1 (1987). This work was commissioned by the American Composers Orchestra and written for and in close collaboration with the violinist Paul Zukofsky and the conductor Dennis Russel Davies, who since then encouraged the composer to write numerous orchestral pieces. The Concerto is dedicated to the memory of Glass's father: "His favorite form was the violin concerto, and so I grew up listening to the Mendelssohn, the Paganini, the Brahms concertos. (...) So when I decided to write a violin concerto, I wanted to write one that my father would have liked." Among its multiple recordings, in 1992, the Concerto was performed and recorded by Gidon Kremer and the Vienna Philharmonic Orchestra. This turn to orchestral music was continued with a symphonic trilogy of "portraits of nature", commissioned by the Cleveland Orchestra, the Rotterdam Philharmonic Orchestra, and the Atlanta Symphony Orchestra: The Light (1987), The Canyon (1988) and Itaipu (1989).

While composing for symphonic ensembles, Glass also composed music for piano, with the cycle of five movements titled Metamorphosis (adapted from music for a theatrical adaptation of Franz Kafka's The Metamorphosis, and for the Errol Morris film The Thin Blue Line, 1988]). In the same year Glass met the poet Allen Ginsberg by chance in a book store in the East Village of New York City, and they immediately "decided on the spot to do something together, reached for one of Allen's books and chose Wichita Vortex Sutra", a piece for reciter and piano which in turn developed into a music theater piece for singers and ensemble, Hydrogen Jukebox (1990).

Glass also turned to chamber music; he composed two String Quartets (No.4 and No.5, for the Kronos Quartet, 1989 and 1991), and chamber works which originated as incidental music for plays, such as Music from "The Screens" (1989 / 1990). This work originated in one of many theater music collaborations with the director Joanne Akalaitis, who originally asked the Gambian musician Foday Musa Suso "to do the score [for Jean Genet's "The Screens"] in collaboration with a western composer". Glass had already collaborated with Suso in the film score to Powaqqatsi (Godfrey Reggio, 1986). Music from "The Screens" is on occasion a touring piece for Glass and Suso, and individual pieces found its way to the repertoire of Glass and the cellist Wendy Sutter. Another collaboration was a collaborative recording project with Ravi Shankar, initiated by Peter Baumann (a member of the band Tangerine Dream), which resulted in the album Passages (1990).

In the late 1980s and early 1990s, Glass's projects also included two highly prestigious opera commissions, based on the life of two explorers, Christopher Columbus (The Voyage [1990], commissioned by the Metropolitan Opera, with a libretto by David Henry Hwang), and Vasco da Gama (White Raven) [1991], a collaboration with Robert Wilson and composed for the opening of the Expo '98). Especially in The Voyage, the composer "explore[d] new territory", with its "newly arching lyricism", "Sibelian starkness and sweep", and "dark, brooding tone (...) a reflection of its increasingly chromatic (and dissonant) palette", as one commentator put it.

After these operas, Glass began working on a symphonic cycle, commissioned by the conductor Dennis Russell Davies, who told Glass at the time: "I'm not going to let you . . . be one of those opera composers who never write a symphony". Glass responded with two 3-movement symphonies ("Low" [1992], and Symphony No. 2 [1994]); his first in an ongoing series of symphonies is a combination of the composer's own musical material with themes featured in prominent tracks of the David Bowie / Brian Eno album Low (1977), whereas Symphony No.2 is described by Glass as a study in polytonality. He referred to the music of Honegger, Milhaud and Villa-Lobos as possible models for his symphony. With the Concerto Grosso (1992), Symphony No. 3 (1995), a Concerto for Saxophone Quartet and Orchestra (1995), written for the Rascher Quartet (all commissioned by conductor Dennis Russel Davies), and Echorus (1994/95), a more transparent, refined, and intimate chamber - orchestral style paralleled the excursions of his large - scale symphonic pieces. In the four movements of his Third Symphony, Glass treats a 19-piece string orchestra as an extended chamber ensemble. In the third movement, Glass re-uses the chaconne as a formal device; one commentator characterized Glass's symphony as one of the composer's "most tautly unified works" The third Symphony was closely followed by a fourth, subtitled Heroes (1996), commissioned the American Composers Orchestra. Its six movements are symphonic reworkings of themes by Glass, David Bowie and Brian Eno (from their album "Heroes", 1977); as in other works by the composer, it is also a hybrid work and exists in two versions: one for the concert hall, and another, shorter one for dance, choreographed by Twyla Tharp.

Another commission by Dennis Russell Davies was a second series for piano, the Etudes for Piano (dedicated to Davies as well as the production designer Achim Freyer); the complete first set of ten Etudes has been recorded and performed by Glass himself. Bruce Brubaker and Dennis Russell Davies have each recorded the original set of six. Most of the Etudes are composed in the post - minimalist and increasingly lyrical style of the times: "Within the framework of a concise form, Glass explores possible sonorities ranging from typically Baroque passagework to Romantically tinged moods". Some of the pieces also appeared in different versions such as in the theater music to Robert Wilson's Persephone (1994, commissioned by the Relache Ensemble) or Echorus (a version of Etude No.2 for two violins and string orchestra, written for Edna Mitchell and Yehudi Menuhin 1995).

Glass's prolific output in the 1990s continued to include operas with an opera triptych (1991 - 1996), which the composer described as an "homage" to writer and film director Jean Cocteau, based on his prose and cinematic work: Orphée (1949), La Belle et la Bête (1946) and the novel Les Enfants Terribles (1929, later made into a film by Cocteau and Jean - Pierre Melville, 1950). In the same way the triptych is also a musical homage to the work of the group of French composers associated with Cocteau, Les Six (and especially to Glass's teacher Darius Milhaud), as well as to various 18th century composers such as Gluck and Bach whose music featured as an essential part of the films by Cocteau.

The inspiration of the first part of the trilogy, Orphée (composed in 1991, and premiered in 1993 at the American Repertory Theatre) can be conceptually and musically traced to Gluck's opera Orfeo ed Euridice (Orphée et Euridyce, 1762 / 1774), which had a prominent part in Cocteau's 1949 film Orphee. One theme of the opera, the death of Eurydice, has some similarity to the composer's personal life: the opera was composed after the unexpected death in 1991 of Glass's wife, artist Candy Jernigan: "(...) One can only suspect that Orpheus' grief must have resembled the composer's own", K. Robert Schwartz suggests. The opera's "transparency of texture, a subtlety of instrumental color, (...) a newly expressive and unfettered vocal writing" was praised, and The Guardian's critic remarked "Glass has a real affinity for the French text and sets the words eloquently, underpinning them with delicately patterned instrumental textures".

For the second opera, La Belle et la Bête (1994, scored for either the Philip Glass Ensemble or a more conventional chamber orchestra), Glass replaced the soundtrack (including Georges Auric's film music) of Cocteau's film, wrote "a new fully operatic score and synchronize[d] it with the film". The final part of the triptych returned again to a more traditional setting with the "Dance Opera" Les Enfants Terribles (1996), scored for voices, three pianos and dancers, with choreography by Susan Marshall. The characters are depicted by both singers and dancers. The scoring of the opera evokes Bach's Concerto for Four Harpsichords, but in another way also "the snow, which falls relentlessly throughout the opera (...) bearing witness to the unfolding events. Here time stands still. There is only music, and the movement of children through space" (Glass).

In the late 1990s and early 2000s, Glass's lyrical and romantic styles peaked with numerous projects: operas, theater and film scores (Martin Scorsese's Kundun, 1997, Godfrey Reggio's Naqoyqatsi, 2002, and Stephen Daldry's The Hours, 2002), a series of five concerti, and three symphonies centered on orchestra - singer and orchestra - chorus interplay. Two symphonies, Symphony No.5 "Choral" (1999) and Symphony No.7 "Toltec" (2004), and the song cycle Songs of Milarepa (1997) are thematically meditative. The operatic Symphony No.6 Plutonian Ode (2002) for soprano and orchestra was commissioned by the Brucknerhaus, Linz, and Carnegie Hall in celebration of Glass's sixty - fifth birthday, and originated as Glass's collaboration with Allen Ginsberg (poet, piano – Ginsberg, Glass), based on his eponymous poem.

Besides writing for the concert hall, Glass continued his ongoing operatic series with adaptions from literary texts: The Marriages of Zones 3, 4 and 5 ([1997] story - libretto by Doris Lessing), In the Penal Colony (2000, after the novella by Franz Kafka), and the chamber opera The Sound of a Voice (2003, with David Henry Hwang), which features the Pipa, performed by Wu Man at its premiere. Glass also collaborated again with the co-author of Einstein on the Beach, Robert Wilson, on Monsters of Grace (1998), and created a biographic opera on the life of astronomer Galileo Galilei (2001).

In the early 2000s, Glass started a series of five concerti with the Tirol Concerto for Piano and Orchestra (2000, premiered by Dennis Russell Davies as conductor and soloist), and the Concerto Fantasy for Two Timpanists and Orchestra (2000, for the timpanist Jonathan Haas). The Concerto for Cello and Orchestra (2001) had its premiere performance in Beijing, featuring cellist Julian Lloyd Webber; it was composed in celebration of his fiftieth birthday. These concertos were followed by the concise and rigorously neo-baroque Concerto for Harpsichord and Orchestra (2002), demonstrating in its transparent, chamber orchestral textures Glass's classical technique, evocative in the "improvisatory chords" of its beginning a toccata of Froberger or Frescobaldi, and 18th century music. Two years later, the concerti series continued with Piano Concerto No. 2: After Lewis and Clark (2004), composed for the pianist Paul Barnes. The concerto celebrates the pioneers' trek across North America, and the second movement features a duet for piano and Native American flute. With the chamber opera The Sound of a Voice, Glass's Piano Concerto No. 2 might be regarded as bridging his traditional compositions and his more popular excursions to World Music, also found in Orion (also composed in 2004).

Waiting for the Barbarians, an opera from J. M. Coetzee's novel (with the libretto by Christopher Hampton), had its premiere performance in September 2005. Glass defined the work as a "social / political opera", as a critique on the Bush administration's war in Iraq, a "dialogue about political crisis", and an illustration of the "power of art to turn our attention toward the human dimension of history". While the opera's themes are Imperialism, apartheid and torture, the composer chose an understated approach by using "very simple means, and the orchestration is very clear and very traditional; it's almost classical in sound", as the conductor D. Russell Davies notes.

Two months after the premiere of this opera, in November 2005, Glass's Symphony No.8, commissioned by the Bruckner Orchester Linz, was premiered at the Brooklyn Academy of Music in New York City. After three symphonies for voices and orchestra, this piece was a return to purely orchestral and abstract composition; like previous works written for the conductor Dennis Russell Davies (the 1992 Concerto Grosso and the 1995 Symphony No.3), it features extended solo writing. Critic Allan Kozinn described the symphony's chromaticism as more extreme, more fluid, and its themes and textures as continually changing, morphing without repetition, and praised the symphony's "unpredictable orchestration", pointing out the "beautiful flute and harp variation in the melancholy second movement". Alex Ross, remarked that "against all odds, this work succeeds in adding something certifiably new to the overstuffed annals of the classical symphony. (...) The musical material is cut from familiar fabric, but it’s striking that the composer forgoes the expected bustling conclusion and instead delves into a mood of deepening twilight and unending night."

The Passion of Ramakrishna (2006), was composed for the Pacific Symphony Orchestra, the Pacific Chorale and the conductor Carl St. Clair. The 45 minutes choral work is based on the writings of Indian Spiritual leader Sri Ramakrishna, which seem "to have genuinely inspired and revived the composer out of his old formulas to write something fresh", as one critic remarked, whereas another noted that "The musical style breaks little new ground for Glass, except for the glorious Handelian ending (...) the "composer’s style ideally fits the devotional text".

A Cello Suite, composed for the cellist Wendy Sutter, "Songs and Poems for Solo Cello" (2005 - 2007), was equally lauded by critics. It was described by Lisa Hirsch as "a major work, (...) a major addition to the cello repertory" and "deeply Romantic in spirit, and at the same time deeply Baroque". Another critic, Anne Midgette of the Washington Post, noted that the suite "maintains an unusual degree of directness and warmth"; she also noted a kinship to a major work by Johann Sebastian Bach: "Digging into the lower registers of the instrument, it takes flight in handfuls of notes, now gentle, now impassioned, variously evoking the minor-mode keening of klezmer music and the interior meditations of Bach's cello suites". Glass himself pointed out that "in many ways it owes more to Schubert than to Bach".

In 2007, Glass also worked alongside Leonard Cohen on an adaptation of Cohen's poetry collection Book of Longing. The work, which premiered in June 2007 in Toronto, is a piece for seven instruments and a vocal quartet, and contains recorded spoken word performances by Cohen and imagery from his collection.

Appomattox, an opera surrounding the events at the end of the American Civil War, was commissioned by the San Francisco Opera and premiered on October 5, 2007. As in Waiting for the Barbarians, Glass collaborated with the writer Christopher Hampton, and as with the preceding opera and Symphony No.8, the piece was conducted by Glass's long - time collaborator Dennis Russell Davies, who noted that "in his recent operas the bass line has taken on an increasing prominence,(...) (an) increasing use of melodic elements in the deep register, in the contrabass, the contrabassoon — he's increasingly using these sounds and these textures can be derived from using these instruments in different combinations. (...) He's definitely developed more skill as an orchestrator, in his ability to conceive melodies and harmonic structures for specific instrumental groups. (...) what he gives them to play is very organic and idiomatic."

Apart from this large - scale opera, Glass added a work to his catalogue of theater music in 2007, and continuing — after a gap of twenty years — to write music for the dramatic work of Samuel Beckett. He provided a "hypnotic" original score for a compilation of Beckett's short plays Act Without Words I, Act Without Words II, Rough for Theatre I and Eh Joe, directed by JoAnne Akalaitis and premiered in December 2007. Glass's work for this production was described by The New York Times as "icy, repetitive music that comes closest to piercing the heart".

2008 to 2010 Glass continued to work on a series of chamber music pieces which started with "Songs and Poems": the Four Movements for Two Pianos (2008, premiered by Dennis Davies and Maki Namekawa in July 2008), a Sonata for Violin and Piano composed in "the Brahms tradition" (completed in 2008, premiered by violinist Maria Bachman and pianist Jon Klibonoff in February 2009); a String sextet (an adaption of the Symphony No.3 of 1995 made by Glass's musical director Michael Riesman) followed in 2009. Pendulum (2010, a one-movement piece for violin and piano), a second Suite of cello pieces for Wendy Sutter (2011), and Partita for solo violin for violinist Tim Fain (2010, first performance of the complete work 2011), are recent entries in the series.

Other works for the theater were a score for Euripides' The Bacchae (2009, directed by JoAnne Akalaitis), and Kepler (2009), yet another operatic biography of a scientist or explorer. The opera is based on the life of 17th century astronomer Johannes Kepler, against the background of the Thirty Years' War, with a libretto compiled from Kepler's texts and poems by his contemporary Andreas Gryphius. It was Glass's first opera in German, and was premiered by the Bruckner Orchester Linz and Dennis Russell Davies in September 2009. LA Times critic Mark Swed and others described the work as "oratorio - like"; Swed pointed out that the work is Glass's "most chromatic, complex, psychological score" and that the "The orchestra dominates (...) I was struck by the muted, glowing colors, the character of many orchestral solos and the poignant emphasis on bass instruments".

In 2009 and 2010, Glass returned to the concerto genre. Violin Concerto No. 2 in four movements was commissioned by violinist Robert McDuffie, and subtitled "The American Four Seasons" (2009), as an homage to Vivaldi's set of concertos "Le quattro stagioni". It premiered in December 2009 by the Toronto Symphony Orchestra, and was subsequently performed by the London Philharmonic Orchestra in April 2010. The Double Concerto for Violin and Cello and Orchestra (2010) was composed for soloists Maria Bachmann and Wendy Sutter and also as a ballet score for the Nederlands Dans Theater. Other orchestral projects of 2010 are short orchestral scores for films; to a multimedia presentation based on the novel Icarus at the Edge of Time by theoretical physicist Brian Greene, which premiered on June 6, 2010, and the score for the Brazilian film Nosso Lar (released in Brazil on September 3, 2010). Glass also donated a short work, Brazil, to the video game Chime, which was released on February 3, 2010.

In January 2011, Glass performed at the MONA FOMA festival in Hobart, Tasmania. The festival promotes a broad range of art forms, including experimental sound, noise, dance, theater, visual art, performance and new media.

In August 2011, Glass presented a series of music, dance, and theater performances as part of the Days and Nights Festival. Along with the Philip Glass Ensemble, scheduled performers include Molissa Fenley and Dancers, John Moran with Saori Tsukada, as well as a screening of Dracula with Glass's score. Glass hoped to present this festival annually, with a focus on art, science and conservation.

Glass's completed and projected works include Symphony No.9 (2010 - 2011), Symphony No.10 (2012), Cello Concerto No.2 (2012, based on the film score to Naqoyqatsi), String Quartet No.6, and the operas The Lost (2011 - 2012) and The Perfect American (2011). Glass's Ninth Symphony was co-commissioned by the Bruckner Orchester Linz, the American Composers Orchestra and the Los Angeles Philharmonic Orchestra. The symphony's first performance took place on January 1, 2012 at the Brucknerhaus in Linz, Austria (Dennis Russell Davies conducting the Bruckner Orchester Linz); the American premiere was on January 31, 2012 (Glass's 75th birthday), at Carnegie Hall (Dennis Russell Davies conducting the American Composers Orchestra), and the West Coast premiere with the Los Angeles Philharmonic under the baton of John Adams on April 5. Glass's tenth Symphony was commissioned by the Orchestre français des jeunes for its 30th anniversary. The symphony's first performance took place on August 9, 2012 at the Grand Theâtre de Provence in Aix - en - Provence, France under (Dennis Russell Davies). The Lost is based on a play by Austrian playwright and novelist Peter Handke, Die Spuren der Verirrten (2006). It was premiered in 2013 in Linz (Austria), conducted by Dennis Russell Davies and directed by David Pountney, who pointed out that the English translation of the original German title means "traces of those who lost their way": "[So] not knowing where you are going, let alone where you came from, seems to be a pre-condition. It is also, perhaps, the way we are? Philip’s music is perfect for this kind of abstraction". The Perfect American was composed in 2011 to a commission from Teatro Real Madrid. The libretto is based on a book of the same name by Peter Stephan Jungk and covers the final months of the life of Walt Disney. The world premiere was scheduled for Teatro Real Madrid on 22 January 2013 with British baritone Christopher Purves taking the role of Disney. The UK premiere was scheduled for the English National Opera at the London Coliseum later in 2013.

On December 1, 2011 Glass, together with Lou Reed and Laurie Anderson, joined the Occupy Wall Street protests at the Lincoln Center, reciting from the libretto of his opera Satyagraha (1978 - 79), which had the final performance on the same evening. A Website dedicated to Occupy Wall Street points out that "it is no doubt timely that Philip Glass's opera 'Satyagraha' - which depicts Gandhi's early struggle against colonial oppression in India - should be revived by the Metropolitan Opera in 2011, a year which has seen popular revolutions in North Africa, mass uprisings in Europe and the emergence of Occupy Wall Street protests in the United States. (...) we see a glaring contradiction in ‘Satyagraha’ being performed at the Lincoln Center where in recent weeks protestors from Occupy Wall Street have been arrested and forcibly removed for exercising their First Amendment rights to peaceful public assembly." And as the composer states: "Unfortunately, there's always a good time to do this opera. It's just the way it is. But never has it been so close at hand (...) My position is that this is free speech and free assembly. (...) And what these people do by acting in this way, they bring back to us the importance of our basic freedoms."

Aside from composing in the Western classical tradition, his music has ties to rock, ambient music, electronic music, and world music. Early admirers of his minimalism include musicians Brian Eno and David Bowie. In the 1990s, Glass composed the aforementioned symphonies Low (1992) and Heroes (1996), thematically derived from the Bowie - Eno collaboration albums Low and "Heroes" (composed in late 1970s Berlin).

Glass has collaborated with recording artists such as Paul Simon, Suzanne Vega, Mick Jagger, Leonard Cohen, David Byrne, Uakti, Natalie Merchant, and Aphex Twin (yielding an orchestration of Icct Hedral in 1995 on the Donkey Rhubarb EP). Glass's compositional influence extends to musicians such as Mike Oldfield (who included parts from Glass's North Star in Platinum), and bands such as Tangerine Dream and Talking Heads. Glass and his sound designer Kurt Munkacsi produced the American post punk / new wave band Polyrock (1978 to the mid 1980s), as well as the recording of John Moran's The Manson Family (An Opera) in 1991, which featured punk legend Iggy Pop, and a second (unreleased) recording of Moran's work featuring poet Allen Ginsberg.

In 1970, Glass and Klaus Kertess (owner of the Bykert Gallery) formed a record label named Chatham Square Productions (named after the location of the studio of a Philip Glass Ensemble member Dick Landry). In 1993 Glass formed another record label, Point Music; in 1997, Point Music released Music for Airports, a live, instrumental version of Eno's composition of the same name, by Bang on a Can All-Stars. In 2002, Glass and his producer Kurt Munkacsi and artist Don Christensen founded the Orange Mountain Music company, dedicated to "establishing the recording legacy of Philip Glass" and, to date, have released sixty albums of Glass's music.

Glass has composed many film scores, starting with the orchestral score for Koyaanisqatsi (1982), and continuing with two biopics, Mishima: A Life in Four Chapters (1985, resulting in the String Quartet No.3) and Kundun (1997) about the Dalai Lama, for which he received his first Academy Award nomination.

The year after scoring Hamburger Hill (1987), Glass began a collaboration with the filmmaker Errol Morris with his music for Morris's celebrated documentary The Thin Blue Line. He continued composing for the Qatsi trilogy with the scores for Powaqqatsi (1988) and Naqoyqatsi (2002). In 1995 he composed the theme for Reggio's short independent film Evidence. He even made a cameo appearance in Peter Weir's The Truman Show (1998), which uses music from Powaqqatsi, Anima Mundi and Mishima, as well as three original tracks by Glass (who is actually briefly visible performing at the piano in the film itself). In the 1990s, he also composed scores for Bent (1997) and the thriller Candyman (1992) and its sequel, Candyman: Farewell to the Flesh (1995), plus a film adaptation of Joseph Conrad's The Secret Agent (1996).

In 1999, he finished a new soundtrack for the 1931 film Dracula. The Hours (2002) earned him a second Academy Award nomination, and was followed by another Morris documentary, The Fog of War (2003). In the mid-2000s Glass provided the scores to films such as Secret Window (2004), Neverwas (2005), The Illusionist and Notes on a Scandal, garnering his third Academy Award nomination for the latter. Glass's most recent film scores include No Reservations (Glass makes a brief cameo in the film sitting at an outdoor cafe), Cassandra's Dream (2007), Les Regrets (2009), Mr Nice (2010) and the Brazilian film Nosso Lar (2010). In 2009 Glass composed original theme music for Transcendent Man about the life and ideas of Ray Kurzweil by filmmaker Barry Ptolemy.

In the 2000s Glass's work from the 1980s again became known to wider public through various media. In 2005 his Concerto for Violin and Orchestra (1987) was featured in the surreal French thriller, La Moustache, providing a tone intentionally incongruous to the banality of the movie's plot. Metamorphosis: Metamorphosis One from Solo Piano (1989) was featured in the reimagined Battlestar Galactica in the episode "Valley of Darkness", and in 2008, Rockstar Games released Grand Theft Auto IV featuring Glass's "Pruit Igoe" (from Koyaanisqatsi). "Pruit Igoe" and "Prophecies" (also from Koyaanisqatsi) were used both in a trailer for Watchmen and in the film itself. Watchmen also included two other Glass pieces in the score: "Something She Has To Do" (from The Hours) and "Protest (Act II Scene 3)" (from Satyagraha).

Glass described himself as "a Jewish - Taoist - Hindu - Toltec - Buddhist", and he is a supporter of Tibetan independence. In 1987 he co-founded the Tibet House with Columbia University professor Robert Thurman and the actor Richard Gere. Glass was a vegetarian.

Glass has four children and one granddaughter. Juliet (b. 1968) and Zachary (b. 1971) are his children from his first marriage, to theater director JoAnne Akalaitis (married 1965, divorced 1980). Granddaughter Zuri (b.1989) is Zachary's daughter. His second marriage to Luba Burtyk was dissolved. His third wife, the artist Candy Jernigan, died of liver cancer in 1991, aged 39. Marlowe and Cameron are Glass's sons with his fourth wife, Holly Critchlow (from whom Glass is divorced). Glass lives in New York and in Cape Breton, Nova Scotia. He was romantically involved with cellist Wendy Sutter from 2008 - 2010.