For much of his life Pierre Boulez was preoccupied by the idea of a work being continually ‘in progress’. So many of his compositions exist in multiple versions that those which don’t – his early masterpiece Le marteau sans maître (1953–5), for example – are the exceptions that prove the rule. And while Messagesquisse (1976), which opens tonight’s concert, is one of those exceptions, it also represents the first link in a chain of pieces that stretches over several decades.

Written for solo cello and an ensemble of six cellos, it was conceived as a 70th-birthday present for the Swiss conductor and new-music patron Paul Sacher. Along with 11 other composers, Boulez was asked to write a work using only six notes, each corresponding to a letter from Sacher’s surname: E flat (‘Es’ in German notation), A, C, B (‘H’ in German notation), E and D (‘ré’ in the French system). Typically, Boulez took this idea a step further, adapting the name, via morse code, into a series of rhythmic motifs so that ‘S’, for example, is denoted by three semiquavers. The title, meanwhile, is a portmanteau of the words ‘messages’ and ‘esquisse’ (‘sketch’) – their shared syllable (‘es’) providing a further nod to the dedicatee.

Pungent, snappy and virtuosic, Messagesquisse dances adroitly between various opposing forces. Large-scale order, imposed by the ciphers, is tempered with small-scale freedoms – an approach Boulez described as ‘local indiscipline’. He also delights in contrasting passages of furious, moto perpetuo energy – deliberately evoking the ‘insane virtuosity’ of Chopin’s B minor Piano Sonata – with thick, stagnant chords and inquisitive pizzicato statements. This tension between attack and stasis, violence and seduction, is one of the core tenets of Boulez’s output. As is his fascination with resonance and patterns of decay – beautifully illustrated in Messagesquisse’s opening statement, as each note of the cipher is picked out by the soloist and sustained by an ensemble cello.

Boulez would return to the Sacher Hexachord – as the cipher came to be known – again and again, weaving it into Répons (1982), Incises (1994) and the next work on tonight’s programme, Dérive 1 (1984). Scored for violin, cello, clarinet, flute, vibraphone and piano, this piece was written as a gift for another new-music champion, William Glock, ahead of his retirement as Artistic Director of the Bath Festival. (Thirteen years earlier, in his capacity as Controller of Music at the BBC, Glock had invited Boulez to become Chief Conductor of the BBC Symphony Orchestra, providing some establishment heft to Boulez’s very particular vision of modern music.)

Dérive 1 displays Boulez’s expert command of sound and texture. The music ripples and shimmers deliciously – ‘a new-music lollipop’, as one commentator described it. After the opening piano gesture – an inversion of the Sacher cipher – we are launched into a dazzling sequence of chords built (mostly) from the same six notes. Harmonies spray and overlap like waves, propelled from within by trills and flutter-tongues. After a final burst – the work’s central climax – Boulez presents the same harmonies on their side, spelling them out in a series of timid statements, before a return of the opening material. Dérive 1 is wholly atonal, but its sumptuous facade makes it the perfect gateway for the atonally sceptic, leaning as it does towards the influence of Messiaen, Boulez’s harmony teacher at the Paris Conservatoire, and Debussy, whose music – in particular his writing for flute – Boulez revered and recorded extensively.

As we have seen in Messagesquisse, many of Boulez’s titles have double meanings. Dérive 1 is ‘derived’ from previous material (ie the Sacher cipher) but also features a ‘derivative’ musical form (ie a sequence of variations). Similarly, Initiale (1987), scored for seven brass instruments, makes play on the ornate ‘intials’ or drop-caps found in medieval manuscripts. A short, energetic fanfare, it was commissioned for the inauguration of Houston’s Menil Collection and conceived as a correspondingly ornate ‘initiale’ for the newly built museum. (As it happened, Initiale also opened the inaugural concert at Berlin’s Pierre Boulez Saal in 2017.) Inevitably, it became the ‘initial’ version of another work in progress: in 1992 he expanded and repackaged it as an 80th-birthday surprise for conductor Georg Solti.

Initiale is a good example of the huge demands Boulez places on performers. The score is a mass of imitation and counterpoint. There are precise rhythms and articulation, sudden shifts in metre and long, elaborate statements that cover a vast expressive range. The combined effect, however, is hypnotic. And Boulez’s grouping of instruments into two ‘choirs’ lends itself well to experiments with spatialisation, heightening that sense of contrapuntal interplay, as he had already done to great effect in the orchestral work Figures—Doubles—Prismes (1957–8).

Up until this point we have heard works from Boulez’s middle and later periods. The next piece in tonight’s concert, the Sonatine for flute and piano (1946, rev. 1949), is one of his earliest. Noisy, unruly, full of compressed rage and savagery, the Sonatine is a homage to Schoenberg and his 12-tone technique, whereby the notes of a piece are governed by a pre-determined row of pitches. Boulez first encountered this ‘serialism’ in 1945, at a concert featuring Schoenberg’s Op. 26 Wind Quintet (1923–4). ‘It was a revelation,’ he later said. ‘In it I found a harmonic and contrapuntal richness and a capacity for development and extension I have never found anywhere else.’

In the Sonatine the 21-year-old Boulez pushes Schoenberg’s method to its limits. Seldom is his row announced squarely as a melody. More often he piles up fragments in thick counterpoint, or explodes them across octaves like shattered glass. Indeed, the rhythmic intricacy and constant shifts in register make the Sonatine a staggeringly difficult piece to perform. And so it wasn’t – at least not by its original dedicatee, the flautist Jean Pierre Rampal, who was put off by its complexity (Boulez had also vetoed Rampal’s regular performance partner as pianist). The premiere eventually took place in 1947, part of a Brussels concert series which brought together early and contemporary music. Boulez didn’t attend, though André Souris, the conductor who instigated the performance, gleefully wrote to inform him of the ‘vociferous protests’ it caused.

In a further nod to his hero, Boulez copied the structure of Schoenberg’s First Chamber Symphony (1906), squeezing four ‘movements’ into one: after a slow introduction we hear a lively ‘first movement’, whose second theme develops into a mock scherzo; the slow ‘middle movement’ sees the flute dance atop a trilling piano melody; then a ferocious, toccata-like finale. Like the work’s title – denoting a short, light sonata – this design invokes a tradition seemingly at odds with the uncompromising modernism that Boulez came to represent. This is, after all, the man who later wrote: ‘All the art of the past must be destroyed.’ It points to a puzzle at the heart of the Sonatine: does its symphonic model hark back, dewy-eyed, or do the structural boundaries in fact make Boulez’s act of tonal vandalism more visible? Perhaps it’s both: a paradoxical fusion of adherence and antagonism.

Boulez himself later grouped the works written around this time into his ‘classical period’, a naïve prelude to the real revolution, in which he and others pushed Schoenberg’s innovations to their ultimate conclusion. Structures 1A (1952) would prove the ne plus ultra of this ‘total serialism’, which extended the principle to every domain of music. But the breakthrough was short-lived. Almost immediately Boulez changed tack, pursuing a more flexible style – one he called ‘organized delirium’ – that placed greater emphasis on musical intuition: ‘I like to give myself rules for the pleasure of breaking them,’ he later quipped. 

The final work on tonight’s programme, Anthèmes 2 for violin and electronics (1997) relates clearly and happily to a musical tradition. ‘In choosing this title I was influenced by a childhood memory of the psalms that were sung during Holy Week,’ Boulez explained, ‘… and by their clear strophic [verse and refrain] structure.’ Indeed, Anthèmes 2 obliquely captures the plaintive, ritualistic atmosphere of : Gregorian plainchant. Its six sections (or verses) are linked and bookended by a refrain labelled ‘free’. And as the dialogue unfolds between violin and electronics – the latter manipulating the former in real time – Boulez creates the sense of a solo voice in multiple parallel with itself – a new-age organum.

The word ‘Anthèmes’ also makes play on the phrase ‘en thèmes’ (‘in themes’), pointing to two melodic ideas that develop with each repetition of the refrain. That Boulez returned to composing with themes and developments – ideas he once railed against – shows a further softening of his image as the Angry Young Man of modernism. (Not long after writing Anthèmes 2, while giving the Edinburgh Festival Lecture, he suggested that ‘perhaps we [ie the Darmstadt generation of the 1950s and 1960s] did not take sufficiently into account the way music is perceived by the listener’.)

Still, the actual musical language of Anthèmes 2 remains consistent with Boulez’s central concern of pushing innovation, drawing as it does from techniques developed at IRCAM, the state-of-the-art computer music research centre that Boulez founded in 1977. And, of course, all the classic ‘Boulezian’ traits persist, with its alchemical fusion of idea and sound. Predictably, Anthèmes 2 is also derived from an earlier work, Anthèmes 1, itself derived from … explosante-fixe … (1972–4). Boulez had plans to rework Anthèmes 2 as an orchestral concerto for the violinist Anne-Sophie Mutter. These were never fully realised – a sad but appropriate loss: it will forever be a work in progress. 

Read the full programme on the LSO website